Frozen Ground Conference, Aug 10-11, 2014
Notes taken by Ruth Hazzard and Becky Sideman.
Introductions......................................pg 1
Greenhouses/Tunnels ........................pg 4
Coverings............................................pg 8
Crops ..................................................pg 10
Temperature ......................................pg 14
Fertilization ........................................pg 19
Irrigation.............................................pg 23
Light....................................................pg 24
New Developments............................pg 25
Pests ...................................................pg 27
Research Priorities .............................pg 28
Feedback ............................................pg 29
Eliot intro: Cash all winter with plastic greenhouses; in the 1960’s -- farmers were doing with
glass everything we do now w plastics.
See binders by topic w studies Eliot has collected about the 6 topics. Lots from Europe. NOTE:
These have now been scanned in, and are available as pdfs in Box (a file sharing system like
Dropbox). We can share with anyone who is interested (contact Becky Sideman for access,
[email protected]).
Introductions
Clara Coleman 6500 ft in Colorado, 39th parallel, good sun, huge T variations, very windy
location, now in Portland ME.
Eliot Coleman, inspiration from coldframe put inside greenhouse. Mostly movable
greenhouses. Lots of low quick hoops. Gross 165,000 from 1.5 acre last year.
Vern Grubinger: Confernce 2 falls ago on GH, posted all the talks on website. Photo tech.
Christa Alexendra, Jericho Settlers. Zone 4 (or 3 some winters) Mostly unheated structures,
Ledgewoods. Heat ed rarnois structure, inground with biomass furnace. Heated house for
January harvest. 9 yr winter growing. Livestock, poultry in GH. MORE (later on, more in-depth
presenation): labor is limiting – working for mechanization in gh. Removable big doors at the
ends w metal frames. Sutton seeder and mechanical harvester for greens. Movable houses.
Low tunnels JSS bender electrical conduit, hold up under snow load. 4 ft apart. Pull tight at end,
wrap with heavy twin, snake plactic through two tall stakes at end and tie/weight. OR< lay
plastic and put hoops in fall, leave oopen, plant in spring in March, cover. Eg spinach, early may
harvest. Or put low tunnels farther apart and plant cover crops between. Fall chard cover and
keep through December. 40 ft by 142 long tunnel. Tomatoes april 8, maxim biomass furnace
boiler for underground heat with one loop under each bed. Air heat with propane after
tomatoes planted. Spring crops that work: radishes, salad turnips, pac choi, beetes, scallions,
parsley, clinatro, dill, baby fennel. Don’t overwinter a lot of crops bec of down time and also
vernalization/bolting issues.
Turner Farm, James and Brenna Chase. North Haven ME, 3A, unheated moveable houses, 3 lg
heated GH.
Andre Cantelmo, SouthHampton NH, ‘urban’, Haygrove retrofit w rolldown sides, learn:
chickweed inside winter structures.
Chris Cavendish, FishBowl Farm, Bowdoinham ME, 11 yr, 7 winter, settled on a few winter
crops that work. No heated gh except for propogation house. 30X96 gh (3), 144’s that get
moved. Learn: growing w heat in winter.
Sandy Dietz, MN, 5th year through the winter, 46X126 ft gutter connect, soil heat geothermal
heat pump, 30X96 high tunnel want to minimally heat for winter. Pack are and storage building
cooled and heated with geothermal. Zone 4.
Brett Grosghal, MD Evenstar Farm, open field winter production. GH all unheated. Grown in NC
and in MD, zone 7. Windchill makes it 4-5. CSA year round exhausting. Population genetics and
breeding. Marketplace unsaturated in winter. No hurricanes in winter.
Ben Hartman, Goshen IN, Amish country. They are Mennonite, can use electricity. 2 minimally
heated 2 gh (28 F minimum). Worth it economically to heat, < 1 acre. Gross $120,000. Heuer
Tim and Sam Heuer, Hughsonville NH, 4 30X144 GH, one heated to 32F. 1 benchtop heated gh,
30Z 96 in-ground. Learned from John Biernbaum. Learn: salts in the soil over longterm.
Michael Kilpatrick, Granby NY, 9 yr winter. Outdoor winter growing mini tunnels, movable gh,
haygrove adapted to winter, root storage 90 tons. Chickweed, soils.
David Miskell, Charlotte VT, gh since 1982, 25 yr gh tomatoes. Switched to winter greens 5 yr
ago, out of tomatoes. Focus on Early spring end of Feb on, summer basil (DM), hot water heat ,
last winter lost a lot of greens. Has big Dutch venlo type gh, have to heat the snow off the glass
GH. And Harnois. Learn: not lose crops OW.
Skip Paul, surrounded by ocean water. Mild winters able to overwinter easlily, wind hurricanes
biggest threat. Gutter connect heated with used motor oil. Bottom heat water boilers. Heated
gh several for tomatoes. Aim to get out in field as early as possible, March. Get into gh Sept
15, out March 1 for tomatoes. Timing in fall is so key.
Lisa Turner Freeport ME, zone 5. Started winter production 18 yr ago. Gutter connect is 3
ledgewoods put together. Heats most houses for winter. Switched to propane after govt
subsidy for used cooking oil drove price up.
Greg York. Feed nonprofits, serving diversified food to community, serving people with
developmental disabilities. . 4 30X96 heated and 4 nonheated. Learn:salt buildup, fungal
control, ventilation.
John Biernbaum, UMI. Student farm, many gh, one full of red wigglers, Cold storage combined
w high tunnels allows winter CSA. Nutrient mgt – consider hightunnels as nutrient conservation
tunnels. 15 yr experience w nutrition on gh. Ideas for online course on passive.
Dave Chapman, Thetford, VT built 1st rolling GH. 2 GH: 1 acre and 1.33 acre. Growing
greenhouse tomatoes in winter. Goal to use less energy. Economical expect market is changing
competion w Mexican greens coming in Thetford VT 15 minutes away. Next to CT river.
David Cohlmeyer, Gromley ON, believes in storage vegetables but need fresh greens to sell
storage veggies. Heated (felt it was cheaper to buy propane than to buy more greenhouse
space for unheated production) Ian north of Toronto-- 50,000 sq ft of greens incl microgreens.
Adam Gear. Quick hoops gothic house bender for 14 ft wide tunnel.
Steve Rodrigue, Johnny’s Selected Seeds, seeds.
Becky Sideman– Season extension research.
Eric Sideman. Farm in NH, grow most of our own food. PYO strawberries, early tomatoes.
Learn: new crops to grow in tunnels.
Tom Stearns, High Mowing Seeds. OW seed production, breeding, drying seeds in many gh, 10
farms w/in 4 miles. Looking for genetics and variety needs. Gutter connected house. Isolation.
Mechanization of GH work.
Colin Thompson, Univ MI, upper peninsula extension center, 1st year R&E farm. Incubator
farmer site. 30X192 gh. Putting up 2 “nifty hoop”” side step quick hoop movable houses. Zone
4b. Low cost structures for overwintering that can withstand snow, lots of it.
Jack Algiere, Stone Barns Center, Pocantico Hills NY, large gutter connects (2) w 21 ft bays, 96
long. 62 ft is propagation space.
Pete Johnson, Pete’s greens. Craftbury vt. 80 ac outdoors, 3 ac under cover, 2 ac is harnois
tunnel. 30 by >100 ft pole built gh, good ventilation very tall 19 ft tall, single layer, 11 years old.
35X100 ft moveables. About to be done w them. Spring move off, wind damage after
transistion. October – moving ON, soil so humid there’s a lot of moisture to drive off, locked in
all winter. Harder to build up rich potting type gh soil when its uncovered. Some cleansing of
soil but insteady state gh system, after a certain point don’t have to build up soil much more.
Eliot: leeks in 9 inch hole with 1 inch out, sell all winter, move gh over leeks end of November;
replace leeks with baby carrots. Vern: climactic range is hug in new England. Many days when
gh does not thaw out. Doing more growing into Dec then harvest and store. Michael stores
leeks in bulb crates with airflow high humidity low T till March. Turn upside down after you
harvest for 1 day to drain water. John C, TP leeks into soil in root cellar at 40 F. also tried tp in
cold gh close together, root and grow a little, keep very well.
Judson Reid, Cornell extension, high tunnels, more in warm season crops but has been working
on pest management in cool system heat.
Greenhouses/Tunnel Structures
High tunnels = something you can walk in.
Gutter-connects – how many? 7-8 people have them
Benefits: energy curtains inside; larger. You get more light from a free-standing house
than a gutter connected house, but you save energy. It’s because of edge effect; the center
bays get much less light. In way northern eurpoe the glass houses are stand alone. Also more
framing members.
Has anyone messed with the chinese “earth-shelters”? (greenhouses built into the ground
on North side, or insulated North wall).
Curtis Milsap, Missouri – grower that has built one – see link.
Insulated wall, instead of earth
Eric: Frank Gross, Lisbon ME had these structures back in the 1980s
Outside roof insulation problem in snow
Light from north a major concern? (Cohlmeyer, Turner)
Healthier plants if you shovel off the N side. Cloudy day N is equal; sunny day
matters because need light (lumens) to grow biomass. You can fix the heat but
cant fix the light—I want all the light I can get.
Reflected light, bouncing?
Reflected light with insulated bubble wrap on north wall, does that produce
useful light? Lisa T researched, says no.
Size of tunnel? Bigger = better. Geodesic dome over whole farm? Flip-side, ventilation/air low
and NOT compartmentalizing pests.
Shape? Angle of incidence how much does it matter? Gothic better than Quonset because it
sheds snow better. Peak GH with straight line peak and vertical wall are not the same,
difference in how the snow comes off and . Gothic has curve in wall. Vern: what makes GH
collapse: where the weight is after snow comes off, drilled bows vs clamped (drilling weakens),
have to have place for snow to go, snow piling on one side (Rimol, Ktichen Garden). One of
benefits of heating, melts off side. Useful to know which way is your prevailing wind in a
snowstorm because tunnels act as giant snow fences – if wind is in line with the gutters its
better does not pile up between gutters. One collapse occurred because the addition of
another building changed the accumulation of snow. Spring thaw is the most vulnerable time;
when high wind comes. Anchors are weak in mud. One Solution: sonitubes, 18-24” straight
down to ledge, 36” screw-in anchors; dead-man anchors (6” concrete with rebar in it). Another:
Horizontal connection underground (Chris Cavendish’s neighbor); ‘underground purlin’. Dig 20
inches and connected ground posts underground horizontal (ground posts 36 inches deep). Skip
Paul has a system. Lisa Turner: Type of soil changes calculations that you need: finegrained
marine lacustrine (4 ft post), till, sand – all different. Another variable: plastic vs rigid endwall –
plastic likely to turn your greenhouse into a parachute. Places htat give: wigglewire
attachment; doors that open; rigid endwalls. If it opens up someplace, the whole thing goes.
Finish it all the way not 80% See Ed’s talk at high tunnel workshop on how tunnels fail (link is
here: http://www.uvm.edu/vtvegandberry/HighTunnelConference2012.html) . Door latch.
Wind guard covering rollups.
Orientation? E-W for sun. Structural stability is the most important thing (brett grosghal).
Biggest storms are your biggest limiter – where do they come from. (If storms come primarily
from East or West, snow will blow off more easily). N-S is better (N-S greenhouses offer more
uniform light, since shadows from structural members of the house move throughout the day).
(For a good discussion of orientation, see p.2 of this document by W. Roberts, Rutgers
engineer: http://aesop.rutgers.edu/~horteng/Workshop/Lecture3.pdf). N-S also provides more
light during April-October, when sun is high in sky, but not during winter months. Ben
Hartman: highest yield per sq ft tracked in all gh found that the North-South, smaller, gh had
highest yields, surprisingly. Old books recommended oriented 15 degrees east to capture
morning light (which is 10-30% more intense than afternoon light). Theoretically you need to
have at least 2x the height in space between tunnels to prevent shading; helps if you can
stagger and put the north ones higher in elevation.
This report (available in google books) may be of interest: Bulletin 144: Mass Agricultural Expt
Station, The relation of light to greenhouse culture, by George E Stone, July 1913.
Automation:
Several people in the room (10) have weather stations, and automatically close down the house
in case of high winds or rain
Antiflap – steel that goes over the arch (Harnois) ?
Coverings:
Anyone have polycarbonate?
Dave Chapman – polycarbonate sidewalls; glass tops.
Sandy using acrylic; lasting longer than polycarb which will start yellowing in 10 yrs
Skip using woven poly from Robert Marvel for rollup sides; Solarig woven
polypropylene, has used for 5 yrs
Additives? Most people using AC/IR (anti-condensate, infra-red reflecting) – only on
inner layer. AC only lasts 2-3 years. If there is a lot of dripping, you need more ventilation.
Polycarbs rec by John Bartok: GE Lexan thremoclear PLUS, GE Softlite lexan thermoclear
PLUS, Palram Americas thermaglas SLT; All three are about $3/sf installed, require aluminum
extrusions.
(In this article, AJ Both from Rutgers compares glazings:
http://njveg.rutgers.edu/assets/pdfs/ajb/glazing.pdf).
If you don’t change your plastic – lose light, dramatically. Use lumen meter because can’t tell.
The one Vern mentioned that a PAR (photosynthetically active radiation) meter made by
Spectrum Technology, is $200 (http://www.specmeters.com/store/quantummeters/?F_Sort=2). Another mentioned by Vern later is a handheld one made by SunSystems:
http://growershouse.com/sun-system-handheld-par-meter-w-detachable-sensor (available at
several retailers). Several others exist. New plastic should have around 70% light transmission,
when it drops below 60% you need to do something (John Biernbaum).
Washing glass? Dave C does it 4-5 times per year; many of the Dutch wash every 1-2 weeks
(mechanized).
Harnois uses curved perlins that curve away from the inner layer. Solution: tack plastic on early
in the morning; tighten the plastic after the sun heats it up.
What’s the ideal dead air space? If greater than 4-6”, get currents in there and reduces
efficiency.
Space between houses? Esp for thawing snow. Need to be 25 ft apart in winter to avoid shade.
Or – more, 30 ft. Or drop base height of more southern house. Rule of thumb: space apart 2x
the height of the southern house. At 42 lattitude.
Drainage: Lack of forethought about where the water is going to go is one of the big problems.
Raising the base about 2 ft; ditch to run water away. Drain tile all around. Water flowing
through house takes heat away. Inner tile intercepts water. Make plastic gutter on the outside
drain before you bury the drain pipe. Drain on inside or outside? Outside: Gravel around the
4inch drain tile . Polycarb kneewalls (Arnolds), gravel airspace reduces movement of heat out of
the soil inside. Inside: reduces freezing.
Jack: uses French drains on hillside to reduce flow. Greg York: rigid insulation next to
greenhouse, sloping away 1X24 inch, covered in landscape fabric and wood chips, vertical or
horizontal placement is the same effect. Eliot: hates plastic foam does not use it. Plants edge
beds to turnips. Jon Satz, foam board protected by sheet metal.
Single vs. Double covers? Single covers of gh to maximize light. But after last winter wished he
had double. Brett went to single instead of double for more light in January. Resolve problems
with greater cold by using more cold-tolerant varieties/species. Paul: single layer moves more,
gets scars and nicks and loses light, can’t stand losses to wind, also wants to maximize light.
Sheltered area. Use row covers below to keep temp up below. John B: Double gives you extra
4-5 degrees on really cold night. What really matters is what’s under the cover. Eliot:
disadvantage of single cover – frost on the inside everymorning from the moisture, takes a long
time for sun to melt that off, don’t get that in the double cover. Paul: increases inflation
pressure when hurricane is coming. If you used energy curtains, get frost. Paul: if you have that
much frost you are not ventilating enough. Paul uses vents open all the time; went away from
the “tighten up” philosophy, and now has fewer problems with row covers freezing and frost
inside. Shuttered vents on end, always open. Eliot: Heat radiating from soil at night does not
reflect off plastic as it does off glass, but it does off water (ie frost). Andre: cranks up heat in
the morning and opens the house. Exchanges air, blow off moisture. Can’t leave vents open.
Less disease.
Humidity management:
Andre is heating at sunrise and blowing out the moisture to reduce humidity; and has reduced
disease.
Vern - humidity management – butterfly vents at top that can seal up, or be wide open.
Michael K closes vents at 20; because he heats at 10F.
Jack Algiere – solar vents from Farm tek at tops of end walls, work well.
John B – a grower in MI theorized that cold temps at night were less important than having the
spinach thaw out in the day (to avoid brown leaf edges), so would heat in the daytime when
colder.
Sandy – thaws out lettuce to harvest during the day.
Ann H – over 85% humidity is an issue from a disease perspective (via Ruth).
Dave C: is anyone measuring RH? Reliability of digital RH meters? Especially unreliable at high
humidity, 90%.
David C; blows in air all the time above 10 F day and night. Jack: fan w solar panel, fit in top of
vent. Dayton porterhorse fan, vent fan, low decibel fan. Vern: solar activated fan? Battery
storage vent, uninvent. Louvred vents to wiggle wire in a section of plastic. Adam: Johnny’s is
making an auto vent. Plug-in or popup vent
Moveable houses:
Eliot: latest design: wheelbarrow wheel, axle into metal frame. House sits flat on ground when
the wheel is not in use. About $25 per wheel, five per side. Passion for moveables. House only
over the crop when it needs it. 36 inch screw in anchors from garden tool catalogue. Brenna:
has 5 moveable, track system. Skids need a lot of muscle; there are issues of best system to
move. They are in windy site the can anchor well. Attach to scres in anchors with chain and
chain anchor on each corner and middle. Use earth auger to anchor to – by hand. Eliot: gets
15% more yield after green manure.
Pete Johnson – moving tunnels over fall-planted things = humidity is too high in the soil and
hard to manage over the winter. When you remove the tunnel off of spring things, they suffer
in the transition of being exposed to spring.
Eliot: Leeks a good crop to have the tunnel moved over in early november.
Michael K – can store leeks successfully in plastic bulb crates, 99% humidity, until Mar, around
32F.
Pete J – in Holland, leeks are turned upside down for 1 day after harvesting to allow moisture to
drain.
Can store in bins, as long as you put in upright drainage pipes for airflow in the bin.
Doors into the greenhouse:
Eliot putting doors in sidewalls;
Lisa likes rollupdoor from rimol.
Lisa: gutter connect made from 3 ledgewoods. Drains (underdrains) in center of gutter connect
and all around perimeter. Everyone likes working in it. Melts w greenhouse heat. Puts gutter in
the crevice between. Aphids controlled by watering in January.
Drop down sides – Andre likes them, can roll them down in the winter, gets a god seal and has
cleats to hold uup. Plows snow away from all his houses. Has a pad out 4 inches from gh. No
snowblower. Vents well with a short drop in wall. In March, bottom of sides still frozen, can still
get vent from side opening, needed because hot even if end vents open.
Coverings
Brett uses only 30 weight. Keep crops from freezing. Directly on greens and fresh herbs. 20%
loss from freezing. Pulls off every day. Gets 10-12 cuts from lettuce, 5-8 from brassicas. Cuts
above meristem. Cover depending on weather forecast. Never moves remay when the plants
are frozen. Harvest with poultry scisssors. Likes rough tillage; high tillage makes poor tilth.
Several growers (6-8) use row cover right on crop. Michael: On Spinach, stockpile system
covered in November on field grown spinach with one layer tunnel and two layers of ag 19 or 1
layer of ag 30. Not removed except for harvest. Not trying to get growth, just storage. Eliot
found that after 4 days of gray weather it was colder under ag 30 than under ag 19.
Chris – no supports, but makes sure row cover stays dry. If wet, get crop damage when freezes.
Sutton seeder, tractor beds – everything to reduce labor. Baby small stuff pull row cover off
everyday. Unheated single layer baby greens. Cut into January, stop, reseed early feb or march.
Uses covertan 30. Two layers when colder.
Christa: Uses covertan 30, uses one, two or three layers depending on outdoor temps
predicted. (Exactly what Sandy & Paul do).
Wire wicket? More (12-14) growers do this. What height – study at Walker Farm: 2 ft high was
warmer than 1 ft or on crop. Arnold’s found that closer to crop was warmer on the coldest
nights. Becky: if you leave the covers on in the day you get less heat into the soil. John B uses
conduit cut in half and uses over kale that grows tall by spring. 6ml polyethelyne.
Most people using AG19 (0.55 oz) or AG30 (0.9 oz).
Problem with Typar – little fibery fragments dropped.
Used one or two covers during last winter with outdoor temps – 20 F. If covers are frozen, don’t
remove.
If you are covering only at night, is a layer of plastic on top of rowcover beneficial?
Jack: floating cover on high tensile or with monfiliment. Hung above level of metafim waterers.
Lines are 12 ft apart from each other. Easy to open up. Covertan 19. Uses one layer inside.
Leaving plastic on, suffocating the CO2 so no growth when the sun is out (?). But, more
biological activity in soil releases more CO2, thus perhaps not suffocating. Put on at night,
when we expect temp to drop below thermostat temp. Thermister hangs at plant height. Heat
set at freezing.
Robbins Container Corp. catalogue (?)
Two lighter layers better than one heavier layer? Paul & Sandy think yes; so does someone else.
Jack: energy curtains up at roof are attached to trusses every 16-20 ft with a wire system from
truss to truss. High. Not suitable for hoop house. Designed to go in 20 ft section and butt on
overhead girder. Machine driven. Fabric blocks 18% of the light when its new. Swedish –
Svenson is one manufacturer. 35% fuel savings. Could this be retrofit for tunnel?
Possible to use an energy curtain down low; mechanically covering & uncovering. John B Energy curtains research was done at Penn state. Did not matter so much what the covering
was, gives you 40% savings if you have a single layer of glass. Originally designed to keep temp
at crop (under curtain) at 70 when gh is heated at 50 above the curtain. Our purpose would be
different with an unheated gh. Aluminum curtains reflect heat back. Whether or not the edges
of the curtain are sealed makes a difference – can get a chimney effect.
Do people weigh down sides? Buy wider than you need. Weight down one side, to hold it in
place so one person can cover.
David C – row cover on top, clear plastic underneath – take cover off first, let light in, when
thaws take off plastic.
What are people doing to efficiently put on and take off? Need engineers.
Andre: Covers only cover half the house, open from the middle out. I have to do two covers
because of the variability of need. Some days I want light. Some just hold heat. Perennial cover
(landscape fabric, 6 oz. white. Can still manage it. Supports w thicker gage 9 wire.
High tensile wire length of beds, 7 lines, slide to end, each covers half the tunnel. Wire outside
edge of each outside bed. Liked 30 better than 19 or tyvec. (tyvec has microfibers, also more
stiff so does not fall to ground on edges.
Rollup sides, adopted to roll covers across – doesn’t work that well, in part because there’s no
weight pulling it down.
If cover whole gh vs each bed separately , heat from paths contributed to high T when cover
whole house. Eliot uses quick hoops inside high tunnel.
John B – light diffusing plastic spreads light all around, keeps cooler in summer. Might keep
warmer in winter. Luminosity plastic (what haygrove’s have).
Brett: what is the light that the plants are seeing? John B: diffused light would reach into
canopy better. Brett: plastics vary in what active wavelengths are transmitted. Plant light
meter measures photons of light in the correct wavelengths (red or blue). (see PAR meter
discussion earlier).
David C: basil damage under plastic but not under row cover at same outdoor T (eg 40 F) – why
– air pockets in row cover? Condensation on basil?
Weight? Paul A – use ag30, doesn’t rip easily going on and off all winter. Two covers. Being able
to pull on it really hard its faster. Pulling two layers at once. Remove during the day (on sunny
days.
What would be the ideal material?
Irrigation;
Netafim sprinklers on risers, many like them.
Jack A keeps the rowcover above the arc of the water.
Use black or IRT plastic?
Paul Arnold: swiss chard and kale on black plastic vs bare ground: under plastic soil T stayed
above 45 F (temperature at which you get growth) while without plastic , it was often well
below 45. Chris Cavendish: uses black plastic w 2 strands of drip tape for spinach. Faster
growth in late winter with black plastic. Water drip instead of overhead. Less chickweed. 2-3
seeds per cell, 128 cell. 4 inches by 6 row, dibble holes mark grid. Gh system includes 17 by 144
that are reset over a field grown crop. Time consuming: driving ground posts, uses jack
hammer. Fits over ground post, preset light by hand. Tolerance 1 inch. Bottom of ground post
taking in soil. Now $1000 to move and reset house, could get down to $700. Get same pipe you
get from rimol from steel supply at half the price.
Sandy tries to avoid greater than 20F swings between day and night temp. Does anyone else
agree? Eliot read a study that reported that plants respond to the average temp of high-low.
Brett – Peter Hendersen, Gardening for Profit, early 1900’s. (online archive:
https://archive.org/details/gardeningforprof01hend). Swore that horse manure produced
warmth and CO2 right at ground level.
Different cover supports and bed layout. Look at % of pathway.
high tensile wire running length of gh; pathways
conduit hoops across width, roll to north side, walk on edge.
two sets of conduit hoops across width, with walkway in middle.
Modular movable tunnels. Jack: 10 ft sections, move over various beds, work fine when eastwest orientation, pulls out when north south. Elliot also has modules with hoop, top rail,
bottom rail that can be picked up by two people and moved.
Crops
Christa @ Jericho Settlers Farm– purchased mechanical harvester for greens, plus Sutton
seeder.
Moveable tunnels, stationary ledgwood, low tunnels in field also (4’ spacing with conduit
quickhoops). Sometimes establishes plastic and tunnel hoops in fall, for spring transplant in
early Mar. Have rarely needed drip for this system.
No longer overwinter mustards, chard, kale, transplant in march to reduce bolting. Overwinter
pac choi (Nov transplant) in unheated tunnels for late winter harvest.
Chris Cavendish: Early new potato, RED GOLD, ROSE GOLD, in may. (presprout under benches
on bread trays), 24 inch between rows, 6 inches in row. Green garlic – all the seconds, small
cloves – broadcast in a bed in Nov-Dec hoophouse. harvest bunches in spring like scallions.
March transplants, head lettuce, escarole, endive, salanova. $ per bed-foot. Each foot 90x5
beds per house in a 30x96 house. Salanovas sold as lettuce mix $12/lb
Eliot: rule that we have to make 1.50 per sq ft over time every two months to make money.
Hakurei hit 3.50 selling tops and roots separate.
Jack: bed rent: sq ft price by the day. Total cost of operation/growing are sq ft divided by total
growing days/bed (300) Rules: 10 days between rotations. Plantings in sept-october; then stop
because maturity time gets too long. Tops, baby carrots (at 50 day for restaurant, threads, $12
per lb, 12 row for baby, good for a certain time of year), lots of other list, specialty heads.
Spring cut flowers beat every vegetable. Summer: ginger. Gross about $140,000 per half acre.
Eliot: heated gh seed December, harvest march. Wholesale, $3 per lb.
Sandy: salad mix $16/lb in winter, $12 in summer. $9.33 per sq ft. Oct to end of May. Arugula
$6.12. Includes all multiple cuts or multiple plantings in each sq foot.
Clara - 4 season farm: 2 oz/sf kale, 2.5 oz/sf spinach, winter 2014.
Brett – Mesclun and herbs, $8 per sq ft over 4 month harvest cycle in 2006.
Need a standard way to present these numbers to compare. Weight per area per unit of time.
Overwintering lettuce in zone 4? Works for Michael. Very tiny transplants going in, October,
one layer of rowcover.
Brett on breeding: Arugula cold-tolerant selection worked well. His selected one lives at 21F.
Increasing number of cuts in Siberian, red Russian kale (past 3 cuts) has not worked well,
outside in MD. ‘Adaptive Seeds’.
What’s the possibility of selecting for hardiness?
Tom: There are biological limits, for sure. There is plasticity, however. Differences between
varieties in yield alone can be several fold. To compare genetics, need very uniform
environment. Edge effect makes tunnel variability very high, difficult to evaluate. To breed for
overwintering, need to put up against harsh conditions. Look at cold damage, regrowth rates
(leave uncovered quite late), greenness under low light conditions, diseases. Need more people
focusing on crop improvement because most breeders are not looking at the scale, conditions,
market, that we are interested in. To breed a crop, you need to understand pollination system.
Lettuce is an easy crop to breed.
How fast can selection be made? Depends on genetics/environment, breeding system of crop,
and inheritance of traits.
Brett: mass selection, selecting only mother plants. Takes 3 years to get crop improvements.
Open field must survive AND be harvested multiple cuts. Hoop house is an advantage because
of rain protection. However crops gone to seed may harbor disease and insects.
Spinach
Jack A – falls back to Bloomsdale. Did a replicated evaluation of Bloomsdales selected by several
sources (Territorial, Frank Morton’s was best by far. So selection during production made a big
difference.
Eliot – Space (several others too). Always in top 3 for all winter production (sandy).
Other spinaches vars: Raccoon, Giant Winter (for early), Pigeon, Corvair (prettiest baby spinach,
very flat, bolts early in spring). Tyee met with mediocre response (in spring).
Sandy looks for early, mid, and late production in her earlier trial. Uses top 10 or top 5 varieties
to get even production.
Andre wants it to be upright for easy harvest, and gets DM. (not that many people have high
DM).
Some do better in different parts of the winter. Problems with spinach: downy mildew, lays too
flat. Selecting in gh – want to select for tolerance to disease. Spinach there is a huge arms race
going on: new downy mildew races coming up, breeders are selecting for 3 counties in CA and
selection is for DM resistance in those counties (and in Europe). If growers have favorite
varieties, we need to take responsibility to save seed on our own farms. Conditions are good in
high tunnel for maturing seed.
Arugula
Germplasm collection in Italy, and here
Frank Morton (Wild Garden Seeds, Philomath OR) working to recover varieties that are in
danger of being lost (e.g. Carmona lettuce, Sandy).
Someone at JSS who focuses on winter crops? Yes as of last year—Steve Rodrigue. Focused on
minihead lettuce. Salanova froze and regrew but minihead melted down after 20 degree.
Arnolds maintain should have hardened off better to increase tolerance to cold. Overwintering
and winter harvested. Komatsuna quite hardy. Winter growing brochure come out.
Are there other vegetables that we haven’t found yet? Eliot searched Wikipedia for ‘culinary
vegetables’ and got a big list. Odd plants in the world that we haven’t found yet? Yes of
course! International vegetables. Jack A – stem lettuce, tsai tsai , zha cai, tsa tsai– Agrohaiti
company, eat stalk of lettuce just as it bolts, nutty flavor. (asparagus lettuce), quite hardy. Csaicsai (Asian kohlrabi, horns on the side, mustard leaves tender) . Eliot - Kirgellanland cabbage,
near Antarctica
Salanova lettuces.
Pete grows them all summer, DM resistant, also good in winter. Selling as heads, not as baby
leaf.
Sandy – doesn’t like the green oakleaf (yellows, centers die out), Michael dropped both
oakleafs. Reds grow more slowly, need to plant about a week earlier. Recut is very slow, but
cut time is great 8 lb in five minutes.
Andre , Jack – bittering on the incised salanova, jack switched to the old lolla rossas to avoid
these problems.
Osborne seed company has the multileaf varieties, best was Osborne’s multileaf 3, selling both
as heads and mix. Sandy felt they didn’t perform as well as the salanovas.
Michael – regrowth didn’t work well on salanovas.
Sandy first seed date Aug 20, weekly for 5 weeks. Oldest kicked out, youngest lost to cold.
Trying again.
Ian found reds are slower growing; need to plant about a week earlier
Sandy D. found tipburn on the oakleaves.
Baby leaf lettuce did not die. Best baby leaf varieties that don’t get DM: Arrowstar, bolsa chia,
refugio, spock, blade, gaviota, a couple more, Lettony (high yielding, good in cold weather).
Favorite lettuce: Triple red lolla rossa ‘Revolution’ – now available in Territorial.
Mixes of same name do change in component varieties. You can ask for the individual varieties
that are in a mix so you can plant them separately.
Chard
Michael K – survived -25 or -30, seems that the Fordhook green is hardier than the bright lights.
Eliot – argentata the hardiest in trials. Seed savers five color silver beet.
Artichoke hardy enough to overwinter?
Eliot overwintered some in the root center, then brought them out. Not very productive
compared with seeded. Andre did this, and was very successful using this method.
Kale. Graines baumaux (http://www.graines-baumaux.fr ). French seed co won’t sell to anyone
in US. APHIS has ‘approved’ countries that you can get seed from: includes NATO countries,
france, turkey, Belgium. (NOTE: APHIS has an exemption for small lots of seed (less than 50
seeeds per packet, less than 50 pkts – available to read here. Otherwise, a phytosanitary
certificate is needed – which some companies might (?) get. These are routinely gotten when
moving plant materials for research purposes).
Diseases/Pests/Insects
Chickweed
Crown rot lettuce (pythium?)– 1
DM lettuce and spinach – 4
Cladosporium – 2
Stemphylium ?
Cyclamen mites – spinach
Aphids – spinach
DM – arugula
Slugs
Voles
Beetworm ?
Specific physiological disorders associated with cold winter growing:
Edema
Trichomes (on spinach)
Andre interested in steam sterilization of beds – a neighboring grower has one.
John B – has knowledge of the history.
How may certified organic growers? Maybe 3/4
Are crop rotations a challenge a challenge for your certifier?
No
Temperature
What minimum temp for backup or emergency heat?
Ben – uses 28 F, gets 2-3x the yields over unheated, save $$ on rowcover removal. Notices that
at 28F, plants do not need to put energy into thawing, are photosynthesizing by midmorning.
Covers the cost.
Eliot: growth may be set back for several days once plants do freeze. Below 25 they saw
damages in lettuces and above did not.
Ben: had compared 28 vs 33F, didn’t notice much of a diff but heating cost was about $100
more/month (heating w/natural gas), $20-30/week for 30x90. Worst was $56/week during
vortex.
Brett: stopped heating; safe temps for fast regrowth is 28F for closed system lettuces (freeze at
31.5 in open field); brassicas will regrow quickly at 24F.
Dave Cohlmeyer: Reds don’t show as much damage, or maybe they don’t get as much damage.
Recover more quickly with soil heat. Got growing again faster.
Lisa T: Used to heat to 33F air heat, heat to 45F at 3.5 ft off the ground. Longest time of
brassicas in dead of winter 8wks, went to 6wks (vs 3 wks in summer). It’s not about soil heat,
but total heat in the system.
Soil heat?
Michael: Used to use ground heat, but they saw more problems with disease, made more
moisture in the air and venting more. If you are going to ground heat you have to take covers
off. Used propane kokogi flash hot water heater, 99% efficient, water heater,
Pete : soil heat reduces hardening of the plants, so they are damaged at higher temp. So, if you
use ground heat, you have to use air heat too.
Lisa used to heat to 33 but at one of the mofga winter growers meetings there were farms who
did in-ground heat and they had fast growth compared to what we were doing; but when they
increased their base heat to 45 the growth rate went up dramatically. Crops matured about
20% faster (8 weeks dropped to 6 weeks).
Eliot Q relation between air and soil temp; what soil temp is minimum for biological activity?
Brett: bacteria and fungi do operate at lower than 45 degrees, general decomposers are active.
John B - nitrifying bacteria are active around 60F, less so below that? Nitrate limiting in cold
soils. Brett: Agreed.
John B: did his masters on bottom vs air heat. Cold soil limiting N uptake.
Pete: anyone heating air just under row cover?
Michael K – Tried it. Found that they had to find a way to get the air to return. Harder to keep
the rowcover down. Blowing down in tubes with air holes. Was using plastic and trying to
recirculate the same air back.
Andre – did it lower tech – used tubes under rowcover, used tunnel as outside air, used it to
combat disease, created a nice puffy tunnel Clipped center of remay to have the full width
covered. Heating to 32F under there. Placement of tubes is important, need to blow up. Need
to perforate the tube with fewer holes in beginning, more at the end – made his own tools with
a propane torch.
Dave Miskell – hot water pipe rail system (like with hydroponic tomatoes), put rowcover over
that.
Eliot: Could you just run a hot water pipe on the soil?
Glycol in the pipes to prevent freezing? Didn’t work for John B.
Benefits to running the forced air in reducing humidity? Dave Chapman – you do get
some air movement with the hot water rails (convection).
What are the energy costs with air heat vs pipes either in ground or above ground. ?
Lisa: have used #2 oil, then cooking oil, then proprane and have equipment to burn all and will
keep all depending on markets and prices. Now locked in $1.93 per gal for propane for this
winter; sure we won’t be doing this forever because situation will change. Infrasturture for
propan is cheap bec they give you the tank and the burners are cheaper. Propane is a
byproduct of refining of petroleum; if not sold is burned off. Not a static answer. Constantly in
flux. Need to compare apples to apples, energy content in different fuels, prices vary widely.
Vern mentioned the Penn State Energy Calculator.
Jack: standard heating systems with propane/air; looked for alternatives and settled on high
efficiency propane heaters. Cost of the retrofit (eg 200,000 for geothermal) Found:
construction heater which are pilotless vent into gh, cheaper, 25,000 for intfrastructure,
propane was 10,000 that year. They are sensitive to co2; don’t fire if too high co2. All porcelain,
everything has to be completely clean, do take maintenance. Co2 sinks to floor, 12 ppm at floor
in early morning. Closed down house. Limit to growth can be availability of co2 and starts at
lower temp if co2 is high. When sun comes out, active photosynthesis begins, you get growth
in the early hour.
Lisa T. All burners are about 80% efficient; but ventless propane gives you 20% more efficiency.
Research: what kind of damage do you get on the typical winter crop if you don’t vent the stack
(e.g. with ventless heaters)?. Given the amount of co2 released. See Bartok fact sheet on
unvented heaters. Indicator plants are petunias and tomatoes. Ethylene gas is another polluter;
0.5 ppm will give problems. You need source of oxygen for burning, so you need an intake
vent.
Vern: problem is it’s a moving target, no single answer. Ha been working with a lot of farms
and wrote up case studies. Loves Penn State energy selector where you can plug in any cost of
different fuels and if produces break even graph. WE cost shared a bunch of different fuel
burners, wood and corn pellets. Best option balancing cost and meeting grower’s needs seems
to be Maxim burn wood or corn, do ½ million btus propane start, can go to different outputs of
heat – air, in ground heat, under bench heat.
Dave Chapman: Buy a CO monitor if you install a ventless heater; or workers will serve as
indicators.
Jack C: Agreed, need sensors for CO and auto shut off if you have an unvented heater.
David C: used unvented heater for a couple of years. Plants were not growing as well, got
mildew, determined that there was a gas in the air as byproduct of the propane. Turned out
the company used a poor quality propane with by product in it one particular year. They could
smell it.
Tom: what about wood chips (don’t need a factory to make pellets). Who is doing chips that are
augered in? Answers: there are these systems, the materials handling is high needs to be
automated as much as possible. Ramping up temp is slow. Vern: analysis over several years has
shown that these systems have about half the fuel costs.
Soil heat using wood chip pile. : Micheal used pex but understands he could have used plastic
bec of low temps al lot cheaper. Shows wire frame system with plastic coil placed underneath a
chip pile, heat generated is pumped into soil of gh. Heats for whole winter. Need to make big
pile. Not too precise about what size of pile. Company that does this has formulas.
Biochar: batch biochar made at night, heat given off can be drawn into gh. Testing & research
going on at Universities. There is a Canadian company working on this.
Digester: Maxwell’s farm using digester have to be able to dial it back as there is so much
waster heat. Food waste could go into digester along with cow manure. Makes electricity, plus
a liquid that has ammonia, plus waste heat. This is in Europe. Is this good for here? Drawbacks:
the seasonality of the heat demand, expense.
Seth Jacobs, pex tubing in the ground, oil heat (300 gal in mild winter). He has zones but may
not be needed if whole house is planted. 2 ft apart 18 inches down (1 ft not deep enough.
Miachael has similar system, does this with coggie hot water heater flash instant, feels 2 ft is
better, heat comes up through ground at 45 degree angle so can put 3-4 inches apart. David at
22 inches deep, Can heat beds with one line, not heating the paths, domestic hot water heater,
ran all winter. Surface temp about degrees warmer than air temp, if warmer you get disease.
Worked for greens. Temp at soil level 2 inches down 50-55 in Michaels. Water runs at 110.
Does not need pex, can use pvc. Pex degrades in light faster than pvc. David C, leave boiler at
110. It takes 2 weeks before I get warm water back, onces it warms up it comes back about 5
degrees cooler. Skip has pvc black poly pipe—have had it in the ground for 25 years. Uses pex
right out of the boiler then switch to poly at manifold. Key is take hot water heater out of
house in the summer because it rusts. When to heat? Not in the fall -- then you are trying to
harden off the plants. Start when it gets much colder. Pete: has laid the pipe with a single
shank subsoiler down the length of the house, tench at each end
Lisa: Physics tells us that heat comes out of the pipe uniformly round, movement when
moisture is present is different. Heat rises.
Eliot: uses wood heat (firewood), blow hot air into the greenhouse. Likes to cut his own.
Outdoor based wood boiler, heating hot water, fire up in advance of cold nights.
Solar hot water to heat water for gh. 22 standard solar not water panels. Uses heat in summer
to keep house dry to prevent disease. Some goes to in ground, some to air, some to home hot
water.
More efficient to run solar pv, then make heat with electricity, compared to solar hot water. PV
panels need much less light to be fully effective, wheras in winter there are a lot of cloudy days
(half).
Sandy Dietz: Econar geothermal system. Built for greenhouse, storage and pack house system.
46 x 126’ GH: level pad, Four foot insulated frost rigid insulation, pad of foam insulation on
ground, the soil, closed system manifold. 20 one hundred foot coils of 800 ft of tube. Run
antifreeze through earth loops and heat pipes. Start with temp around 45-50 and goes down
into 20’s. Does not heat ambient air like we thought. Soil temp at the heat pipes is 65 degrees,
air temp 65 degrees air. We do warm seaon crops. GH build for 90mph wind, 30 lb snow load,
20 lb plant load all at once. Did need air heaters, put in 2 300,000 btu propane heaters and
runs them constantly in the winter. Also uses one 100,000 btu heater to run to pull moisture
out of air, pulls 5 gal of water out a day. Heating soil temp does not heat air as they expected.
Have problems with thrips which has some tolerance in tomato and cukes but not in lettuce.
Tomatoes and cukes have higher value than greens would. This is a 20 ton system. When you
are cooling with it, you dump the heat into the loops which raises soil temp to 65 degrees, so
start with higher temp in the bank. Insulation on sides of the system is key. Use geothermal to
cool cold storage; has gotten good payback. One side at 38, the other side at 45F – floor
cooling. Excessive humidity a bit of a problem. Used also for livestock watering. Looking at
other options for supplemental heat. Cost of geothermal $60,000. GH itself about $70,000 incl
all the soil work.Not sure if she’d do it again. Electricity runs roughly $100-200/month extra.
Looking for alternative backup heat (incl. Garn systems).
Vern mentions Ryan Voland’s earth based heat pump which heats and cools storages as needed
with movement of heat into areas that have been cooled.
Tom: knowing of systems that elegantly integrate energy from one enterprise to another – well
designed and sophisticated and sustainable?
Brett – 2 examples in MD, both went under.
Jack – GreenPower company, Lennox MA – first example: composting, methane, co-gen plant,
greenhouse, to combine waste management and greenhouse production, have been pitching
the idea.
Monitoring: measuring temperature.
How many have a phone alarm? Only about 5-6 growers have alarm systems in general.
Are people in agreement that minimal heat is “worth it” because it increases yields
considerably?
Andre: added heat is not just about increased production, but about quality and not having so
much damage that I have to sort it or throw it out. Sorting greens is throwing money off the
table. Minimal temp of 25 is his rule of thumb for adding heat.
David C: I look at average temp. If wind forecast, keep at 33 degrees at night. If mild winter
night, heat to 50 degrees to make up for cold spells but at lower cost. , Try to keep average at
45 degrees. When sales go down I turn temp down.
What about high temp? looking for surface temp on the soil at 45 degees average. By 9 am its
up to 60 degrees in the house at 9 am. What is everybody’s top temperatures? RH goes up on a
sunny day. Eliot: on a sunny winter day I keep my vents closed till reach 85 degrees to build up
heat in soils. Brett wants high temp once in a while to drive down warmth-loveing disease.
More diff gives longer hypocotyls. (Diff = avg of day temp minus avg of night temp). When its
positive you get more elongation. When you have negative or near zero you can shorten plants.
Has mostly to do with stem growth so not much impact on a rosette like spinach. Internode
space in plant with stems. John B argues that you might not need those high day temps, that
the direct radiation on soil would do the trick without the air temp. How high produces
determimental effects? High temp more detrimental if you are letting it freeze, less if it you’re
not. David C if I get up above 70 then lettuce becomes too tender for washing.
Do we know how soil organic matter affects soil freezing properties, etc?
Eliot – more water holding capacity, so more heat accumulation; but more OM, less
heat storing.
John B – working with engineered soils; postconsumer food waste composted with
horsemanure etc; ?? Possible to do experiments on soil OM and temperature responses,
if desired.
Jack – roughly screened topsoil, airspaded the whole thing to eliminate compaction
without destroying things.
Are HAF fans worthwhile in greens house? It depends. Paul: if no row cover, especially later
winter/March, if you have a lot of extra moisture you need to manage, HAF are worth it. Row
covers are drier.
David C photos: Italian exhaust fan with plastic to reduce flow for winter. Humidity meter.
Used pop bottles hung from cross ties, filled with water, freeze over night, absorb heat in day.
Seed production in winter gh eg fordhook mustard. Greenbelt greenhouse range 50,000sq ft.
captures rainwater in huge tank for watering plants, hot water tubes under benches for warmer
greens, lower for cooler greens; heat curtain saves 35% in winter, keep house cooler in summer
aluminum foil on top. Will add clear plastic above to keep frost off the curtain so it can open as
soon as sun comes up in winter. Aquatherm pad, water trays from below. Engineered soil
between cinderblock walkways, has low fertility (Growbark makes compost from old sawmills
piles of tree bark). Korean LED lights (Parus); they’ve found the best – plants growing about
20% faster. Lettuce in Japanese paperpot system. Transplant quickly. Work well for lettuce and
alliums. Not for carrots. 900 for machine. 1200 investment to get started. Proprietary tray for
pots.
How low can plants tolerate for lettuce, chard? In the gh (not in field); Minus 20. Its all in the
hardening off.
Fertilization
Trace elements that make crops more resistant to cold: K, CA. Adequate CO2 eg from active
compost. High nitrates in tissues?
Fertilizers that people use in their tunnels?
alfalfa meal; mix of alfalfa and soy; kelp (dissolvable kelp with K which can be sprayed on plants
not midday but morning or later afternoon, every two weeks in the spring, once a month in
winter, or add powder to beds – Jack A, Seacrop)
Stirring soil during the winter seems to activate nutrients make them more available, plants
respond with more growth. Andre agrees: uses garden weasel. Spinach after cut harvest, goes 1
to 1.5 inches deep. Ben H. agrees.
Arnolds: apply Rootshield Plus to soil before planting (reversed Fusarium infestation) Water in
across tops of trays in GH, in spinach tunnel after ds, drench using 50 gal sprayer with
Actinovate. Use mushroom compost from PA, no salts buildup. 5% OM, more like regular soil.
Eliot put compost in tunnels at about 40 T per acre annually. 5 gal bucket for every 10 ft of bed.
Crab waste (from New Brunswick). Has anti-nematode properties, microbes feed on chitin
which helps with nematodes and
Soil testing?
most test yearly, some at two years. What kind of test? Regular soil test same as field soil; some
do saturated media; some do both. Several do compost and well water samples, too.
Vern: testing useful to have background data so when something goes wrong you can rule out
or detect problems. Regular soil test gives what’s there. Different acids have different
strengths so different labs give different ppm, look at the ratings. John B: based on weight but
many samples are done with a scoop so for a high OM soil that volume of soil in scoop not as
much weight. Saturated media test – shows you whats immediately available. Also tells you
salts, very important. Nitrogen is very dynamic. What do you need for the crop? Tomato in GH
produces 4 times the biomass as field; but for greens in winter we don’t want to overdo.
Research has shown nitrates not an issue if OM very high, but if soil is juiced with lots of N,
especially if adding soil heat – should be taking nitrate tissue test. What he’s seen is houses
that have been amended for some time have very high P – need to dial that back. If P is really
high and OM is very low move to peat moss. K is often low, especially for tomatoes and even
for greens. (Pete J: try to get tomatoes to wear out the soil, but still too much for a
spinach/lettuce crop.) If you have a big pool of OM may have good micros but not sure what is
an issue. Boron? Several growers have problems. Add boron for beets, and brassica crops. Seed
meals are slow release materials, peak 2-3 months out. I worry about foliar feed wetting leaves.
What’s the benefit compared to watering into roots. Eric: when you put a food source on the
leaf you are opening it up for microbial growth. Sometimes disease organisms could grow
better than plant.
Water pH is not important, it’s the bicarbonate alkalinity. Midwest- groundwater comes from
limestone rock so we are applying lime every time we water. Need to add sulfur to keep soil at
7 (goal). Mineral balancing CA/Mg, add CA if MG too high. Judson Reid: NY water is high in
alkalinity. Ongoing problem. Can we expect the same soil for high production of tomatoes and
cucumbers to be good for crops like spinach and other greens in the winter – wildly different
demands.
You can’t just add compost and assume everything is going to be good. Where is the balance?
When OM is 12=15%, garden symphylans build up they like this environment. They go down
deep into soil, eat all the roots off the plants. Worst with fresh organic matter, uncomposted.
See ATTRA article. Would experience in muck fields soils be useful?
Eliot: his compost-based soil amendment system is producing great greens and roots but
tomatoes stop growing after 7th node.
Brett: MD has strict nutrient mgt laws. We underfertilize as a rule. But GH still have hi nutrient
load, P too high. PA companies are selling a lot of testing and sell fertilizers ---he is seeing
more disease if farms that are using these results.
Vern: tomatoes really do place a high demand on the soils and added N and K gave increase in
yield over just compost (March). High salts in April dropped over the course of the season as
plants took out nutrients. Spike of release from seed meals.
Skip: bank compost into the tomato plants, winter greens coast on what’s left.
Vermicompost vs regular compost? Sandy: Having a worm bin and taking the liquids off it
injected into tomatoes have seen strong growth response. John B: compost with worms goes
faster. doing research, more of a fan of sprinking on the compost than using water extract.
How many folks are rotating tomatoes with winter greens?
Christa A is doing both, following Vern’s recs. Supplement compost at a rate of 3-4 inch layer
per year. Tomatoes did run out of juice. No supplemental fertilization for greens in the fall.
Now uses peanut or soybean meal for longer range fertility. Sulpomag if need P or Mg. Use
saturated media test. Tomatoes when heated ran out of juice later in season used fertication,
but unheated Vern’s recs from saturated media test were fine. Dont add anything for greens.
House that had chickens with wood chip bedding has been difficult to manage, not holding
water well.
Sandy: peat moss comes out cheaper than compost by the yard. No loss in yield. We are off the
scale in P bought a load of peat moss. Eliot the beauty of peat moss is you are getting structural
organic matter, without providing much in the way of nutrients.
Lisa T used to use ½ inch compost annually. Adds peat moss on irregular basis. Aiming for 50 lbs
N/acre on every other crop of greens. Arugula is the one to watch; will discolor sooner than
other greens spp. Alfalfa meal as primary source of N. Sees salt on soil surfaces; EC is not
actually high.
Greg Y tests with Kinsey labs; they do well with the balance of MgKCa using Albrecht system.
Use high levels of plant-based compost, similar to Eliot, in addition to what the soil test is
recommending. Use compost 10 5 gal buckets in 90 ft beds. Compost from herb production
facility, 7% aromatic herbs, pungent and fragrant. Add compost only prior to greens after
tomato. DO have salt issues, but have gotten away from animal manures.
Taking tunnels out of production? Only a few. Brett 2 month out with cowpea. Uncover. Off
for the summer.
Cover crops?
Cowpea, oats, peas, buckwheat
Uncover?
Many remove.
What salt levels are of concern to you?
Dave Cohlmeyer found rising Na levels, couldn’t tell where they were coming from;
coming from high carbonate levels from the water.
Vern suggests water tests: Everris one lab that does it.
David C found sodium levels were going up even though not adding anything. Source high
bicarbonate levels. Need to add citric acid (John B recommends sulfur instead).
LISA ME is testing fertilizers; testing some found either higher or lower numbers than
guaranteed analysis. No penalty for being higher, only for lower, but in either case may not
match your expectations.
Onsite tools: Cardy meter; EC meter; direct read ECB meter from Spectrum Technology can give
quick read on salts but have to be careful how you use it –affected by moisture. Industries.com.
Use a good pH meter: spend >$200 to get a good one. Hannah meter. Judd thinks that s a good
meter. You need bicarbonates reading too and no good handheld meter. Tritiation.
On-site testing?
Spectrum meters has a new probe for quick EC measurements; John B testing – need to
be careful how you use it because it’s affected by moisture.
Hannah pH/EC meters –may have to spend around $200 to get a decent one.
Test strips
$10 garden center meter
There are not good home test kits for water alkalinity – Judson Reid
UMass floriculture website has good fact sheets on gh nutrition including using EC meters and
pens.
https://extension.umass.edu/floriculture/fact-sheets/how-use-ph-and-ec-pens-monitorgreenhouse-crop-nutrition
Brett does not like fish emulsion bec production steals valuable fish from the ocean. There is
another fish emulsion. Most is made from herring and menhaden schools that are processed
for protein. Most goes to animal feed but waste goes into fish emulsion. Raiding the ocean of
valuable fish. Alternative fish emulsion made from carp, invasive fish.
JohnB putting on 6-8 inches of compost, lots will oxidize very quickly. For most healthy system,
you need the four types of OM: living, recently dead, dead, very dead. We need to try to make
this system happen in the GH. Which means not just compost. Ohio State test kit for active OM.
Eliot: can’t search as would like -- Need a library card to be able to search literature to access
library databases.
C02:
Literature on chinese system for producing C02. Does high OM release enough CO2even when
it’s a 45 degrees during the winter? Between 700 and 900 ppm is ideal level. Plants can absorb
CO2andhave benefits up to 9,000, we all fall asleep at much lower. Using in photosynthesis.
Respiration releases CO2 levels go up at night, levels go down as soon as photosynthesis
absorbs c02. As long as T is above freezing and there is motion inside the plant then it can
photosynsthesize at pace that increases up to 90. In tight house plants use of CO2 during day
how much depletion is there without supplemental CO2. If you are venting the house you get
more in but no point in adding co2.
Irrigation
People use drip or overhead – many use both. Few bury their irrigation. What level of soluble
salts is the benchmark?
Greg: irrigation at end of winter to reduce salts (leave overhead on), salts have gone down on
his sandy soils, levels migrate back up over course of season. Don’t see damage but some
things don’t grow (carrots). One grower asks fire dept to come in once a year to flush their
tanks in his greenhouse.
Tom: Israel using 3 ft of water to flush out salts – Israel may be good resources.
Becky: different methods give different results, differ by a factor of 10 or so. Different methods
to measure soluble salts (SME, 1:1, 1:2); different levels are considered very strongly saline
(see http://extension.udel.edu/lawngarden/files/2012/10/CHAP10.pdf). Stick with one lab over
time. Saturated media extract (saturated soil, add water till it glistens, soil should slide off the
spatula).
John B: Numbers given are for soilless media but may be applicable in highly-amended tunnel
soils (?); Table from MSU displayed. Twenty years old has been the standard. What are
appropriate winter growing recommendations? They ran correlations between media salts and
soil test results on test data. He was taught if 10% leaches out that would remove the salts but
he has found that’s not true. When he did expts it took 30-40% leaching to drop salts. So we
realized we were fertilizing too much. John B’s recommendation: let salts come to top, and the
skim them off the top rather than trying to leach them out the bottom. In pots, need to leach
out a container with twice the volume of water. Important point: need to know what salts we
are talking about; many are nutrient salts.
Using peat moss? Yes. In North America we are harvesting less than 1% of the bogs, strict
regulations in Canada. Hoop house is a nutrient conserving tool if we use it that way.
Chris C has a friend that plants seeds in the bottom of a small trough to help with germination
in a high salts situation, the salts will migrate up to the higher ground.
Andre: how do people deal with drip tape being in the way at harvest?
Christa: use overhead for germination, and early in the crop to bank some water. Time
irrigation on a warm sunny day early to mid moring so it dries off before row cover goes back
on in the afternoon. Time it so leaf wetness is really short.
Eliot: we do all irrigation overhead with netafim misters. Not in the way of anything. If you
irrigate a bit heavy for germination, would carry salts down below the seed. We germinate in a
peat vermiculite mix so no nutrient overload. Dan is the Isreali company that sells them;
Rainflo also sells Netafim. Eliot increased the pressure in their system. Takes out gizmo that
prevents drip, he takes them out so they don’t freeze up and put up with dripping, puts lines
over the paths.
Ben: What is white on surface? Eric: When the water evaporates it the salts don’t go with it.
They wick up with water, then left on surface. May be calcium. What’s in it? If you want to
know scrape off and send in for saturated media test compared to soil.
Numbers on watering. Watering in summer: 1-2 inch in the field in summer minimum.
Greenhouse tomatoes summer – 2 inches a week, 8 hrs (do people know how much?) Jack his
netafim misters put out 1 half inch per hour). Eliot does not water from Nov to Feb (?). John B
qualifies that it makes a difference what you start with before covering or before winter. If
they assume no one needs to water could dry out. Andre: go by irrometer as a tool to decide
when to water. Its easy to get busy and not notice need. Best for field under plastic. In GH
combine observation and forecasting. Or, really look at your plants and let them speak. Sandy:
last winter when it was so cold, we couldn’t water because it was too cold, soil was frozen, lost
lettuce because it was too dry. People agree that they keep soil less moist in the GH to avoid
disease. Moist soil builds up and accumulates heat better, but in winter gh, excess moisture is
an issue. Do people use plastic to manage this? Pete uses plastic for everything they transplant,
staked on edges with cut bamboo stake, its black plastic but would use irt if could. Helps with
humidity off the soil. Sandy lays biotelo in their tunnels in winter. Use drip under. Eliot uses
overhead on plastic makes beds with a concave shape to capture water. Vern: What is needed
for tomatoes is not applicable to winter greens. Take home: we don’t know much about how
to measure water. Would growers benefit from research on this? Plastic keeps surface moist
where the roots are and prevents the salts from moving up bec prevent evaporation, helps
keep nutrients distributed in soil profile. Some nutrients get taken up regardless of
transpiration but others depend on it, particularly under cold conditions. Anything that reduces
evaporation has this effect, organic mulch would also have similar effect. To decide about
watering don’t just look at surface – dig a hole!
Supplemental Light
LED lights? Low energy. Wavelength spectrum designed for vegetative growth, not flowering.
David C: You can get ones that you can control with your iphone dial in the wavelength you
want. Growth of microgreens is 20% faster, has eliminated issues with disease, increased shelf
life 50% longer, taste better eg basil tastes like basil. Technology has improved in past few
months. Spectrum varies by crop, he has played around with them and found each crop does
best at certain spectrum. Phillips makes lights for vegetative (Jack uses three reds and a blue
for all the sprouts) and flowering. Power company or other grants may help with cost. Eric
Runkle at MSU has beenworking on led lights. But still too expensive to use on winter greens.
Any recommendations on lumens or foot candles per sq ft?
Jack: recs are based on distance from crop. Has to be close, less than a foot. David C has them
up high. Light for growth is a function of light and time, general number is you need about 10
moles per day to grow well (in dec-jan you are below that which is why plants don’t grow well;
summer its double that) and greenhouse drops it to 65%. Hrs per day of daylight is not a full
measure of how much light you get, because of cloudiness, light intensity, and GH. Eliot:
observation was that under 10 hr per day everything grows more slowly. The testing of food
grown under lights should include the actual nutritional value, test by feeding it to three
generations of mice. Lisa – we get better growth in winter than MI, we also get much more light
eg bright sunny day after a snowstorm compared to very long gray periods. Pete J – can’t use
artificial lighting in organic production in Europe.
New Developments
Bubble pastic in 2, 5, 7 ft widgth, plastic comes with cable on its edge that goes in track and pull
it up over. R1.7, same as polycarbonate. Sold in the US as sola wrap. Can be used for
greenhouse roofing. Clint Ellsworth (603 325 1222) dealer in NH, lasts for 10-12 years. Tech
screw up track over bows. Cheaper than polycarbonate but more than plastic (but need to
compute cost of 2 layers plus inflation fan).
Dave Miskell: Israeli company called Ginegar, black plastic tubes 12 inches in diameter, stand up
against north wall of house. Vertical tubes. Eliot is going to try it next winter with clear tubes.
Put reflective bubble wrap behind. AM Leonard is their importer, and they have clear ones.
Soil solarization – effective in tunnel at weed management. Also common in Europe. Bryan
OHare has recently published an article in The Natural Farmer on this topic. Brett solarizes
seedling flats; for him, temp at ground level is much lower (105), even when 160F temps at 6’
high.
All the European organic houses are using steam for weed control.
Running a bare fallow on some fields that will be used in fall. He also used moveable
hightunnel modules from place to place in field.
Clearing up old beds. Using string trimmer to cut greens off, spread fertilizer, use broad fork,
half inch of compost.
The Market Gardener: successful growers handbook for small scale organic farming. Good new
ideas. Small farm in Quebec, no tractor. (http://www.newsociety.com/Books/M/The-MarketGardener). His farm in quebec is Jardin Grelinette.
Timing of transition from tomato to greens (summer to winter crops)? Sandy: use transplants
for plants going into tomato houses, seed mid Septmeber plant mid October. Half are direct
seeded at same seeding date, harvest about the same time. (No diff in yields between seeded
and transplanted).
Eliot buys VT compost, instead of making his own now. Does he like the coir? No, no-one likes
it.
Andre has transitioned to having some three season tunnels which is less expensive, for his
tomatoes. Come out of tunnel in October. When we strip a house we pack both green and red
tomatoes sell to processor who pays 10 to 15 per box – better than throwing them out.
Haygrove holds tomatoes till about 1st week of November. May be too late to clean up well.
Skip: 1st hour of tomatoes is 1st out, by mid September. Strip out all the tomatoes, then close
up, heat up (120 F, four days), cool down, heat up, goal is thrips knocked down. (David notes
that this also kills volunteer tomatoes).
Lisa: we alternate peppers and tomatoes in every house for better airflow, not so hard to rip
out tomatoes early bec they are in several house.
Latest you seed for winter? MN: Sept 21. CT/David Z: mid October. Jack: Late Oct. Eliot: Sept
21. Andy: Field seedings of spinach after Aug 1st won’t bolt. Sept24-Oct 4 for Christa (for Dec
harvest, vs. spring). Sept 10-20 Sandy & Paul, Michael: clear whole house of organic matter,
water, let it sit for two weeks. Andre: Sept 15 for last seeding in Haygrove (may grow more
slowly than other tunnels). Michael K will harvest from field through fall, keep the harvested
greens for 6 wks prior to harvesting from GH (spinach, kale, head lettuce, etc.) in 20-bu bins.
Weeding tools
Wire weeders, (hand tool, LUCA weeder, can be used around drip tape) go through just
after germination, best time for controlling checkweed. don’t move soil (Jack, Michael, Sandy)
Adjsutable rakes that behave like lely weeders, run right over crop (Groundskeeper rake
– Jack, found that it managed moss and pythium.
Favorite hoes: Collinear hoe (use with thumbs up not down). David C favorite hoe is
called a LoopHoe (Lee Valley).
‘ never weed, always cultivate’: cultivate when you can just barely see the weeds.
Skip – anchors. building modular house with side frame of 3 inch angle iron 6 ft frame.
Anchoring 6 inches drainage pipe, home depot posthole digger, throw in 16 inches of soil, chain
attached, turnbuckle at end of chaine. House pulls at an angle. To remove he ifts straight up . ( I
didnt quite get this.) Sealing the corners of roll up sides– much quicker than wiggle wire, female
piece, push plastic in, put piece over. Griffin sells it -- Tamlock
Tom: trial when they tried to kill 49 varieties of lettuce. Doing trials where environmental
conditions are specific, consistent, so they can compare under different conditions and know
whether differences invarieties are truly from genetic basis. Now have several types of tunnels
to give different conditions. Because gh space is so valuable, ability of plant to survive cold or
resist disease, regrow, etc, is worth more than it would be just in the field.
Suggestion: send everyone the same variety with some variety that everyone planted, have
simple protocol, learn about response indifferent conditions. Remove variables such as variety
and date, collect yield. Pick optimum seeding date for each location. Will design more with
Becky and send out.
Visit greenhouses Quebec? Quebec organic tour of greenhouses September 3. Sponsored by
Candian organic growers. Exican greenhouse. Everthing screened, perimeter plantings to
support beneficials and intercept pests Sunflowers succession crop. (sandy did this, loaded
with beneficials). Food safety: hand wshing everywhere, everybody washes hands, boots,
hairnet, among four sections of greenhouse. Bioloigical pest control. Synbox for synthetic
nutrients. Pick clusters by hand. Cost $5 per lb plus 1 for box.
Plan for using the info: Web page on Vern’s website, will post photos, notes.
Pests
Chickweed: where does it come from? It can come in on compost – do a germ test on new
batches. Eric: You only see it when you don’t disturb the soil as the soil temp drops below 60
degrees. As with winter tunnels. Andre: need to plant cover crops early before chickweed
germs, soil is shaded. Eric” use forage radish to suppress chickweed. David C: don’t plant cover
crop until chickweed has germinated. Usually early September. Andre plans to try solarization
and steaming.
Downy mildew of lettuce and spinach: resistant varieties (and what strains do you have locally)
to test what strain you have: small trial with different varieites that have different resistance,
border and center with susc variety. Christ: cut, spray Actinovate, reduced DM in next. Sandy:
double nickel worked on lettuce to clear it up.
bottom rot on lettuce (white mold, Sclerotinia): have to use copper as preplant drench.
Slanted beds. Put transplants soil block up above soil level so bottom is above ground. Don’t
plant all the way down the root ball. Contans – is it only in 25 lb bag? Any other biologicals?
What conditions favor germination of sclerotia? 24 hr saturated soil activates, must be
continuous. Clock starts when dries out. Tom has trouble with Sclerotinia with seed
production.
Do people use combinations of biologicals? Sandy: Root shield and Actinovate standard on GH
bed prior to planting; used Serenade Soil over potatoes for root diseases. In trays, seed, then
drench with root shield and Actinovate applied with water can. Chris C tosses spinach seed
with root shield WG.
Are seedling transplants stressed because in little cells, compared to faster growth in soil
blocks? (just 3 people are using soil blocks).
Judson Reid: Cabbageworm in brassica greens (Tokyo bekana) Moles and voles: cats. One issue
with insecticide is that temps are low, feeding rate low, if needs to be ingested may not work
well. Slugs. Chickweed under cover. Rotation of spinach, beet, chard all one family, Cercospora
builds up. Tom there are good varieties of resistant beets: boro beets resistant, boldor and lutz
fairly tolerant. Systemic problems need to be addressed such as long term rotations. Aphids.
Reduce nitrogen and helped with aphids and with chickweed. Traditional biocontrols not
working. Ladybug larvae work in cool conditions (Dave Miskell). Try and figure out why the
pests are there: what mistake are we making. Aphids - Brett reduces soil N to control aphids,
Jack and Eliot agree that too high N induces aphids in winter production and that irrigating to
leach N out reduced aphid populations (plants under stress are more attractive to insects). Uses
ducks for pest patrol around the GH. Mow grass around gh and trap voles. We cover
transplants of vine crops for the first three weeks while they are stressed – after 3 weeks they
are no longer stressed and cuke beetle does not come in.
Spinach crown mite – detritivore, breaks down OM in soil; spinach damage is being seen. Paul
saw some efficacy with Azadirect on spinach crown mite. Judson has seen it being overcome in
March just as weather changes, so perhaps not Azadirect efficacy. Cyclamen mite also (Eliot)
Eric’s slides: Step one: knowing what you have. Example: carrots had browning leaves, looked
like disease, turned out to be garden webworm. One spray of Bt effective.
Botrytis on lettuces.
Research Priorities?
What would you like to be engaged in studying?
Eliot - Is there still money to test questions?
Becky - YES. One of the challenges is that there is not ONE SYSTEM that everyone is doing. With
so much uniqueness among farms, you have to distill down the questions to their essence. And
what are their most important questions?
Nutrient requirements for winter crops (5)
Benchmarking
Planting dates that we could count on
Definitive book on Spinach (akin to high tunnel manual)
Soil Management – Brenna
Spinach leaf diseases including cladosporium (3)
Impacts on temperatures on yields (fluctuation, averages, heat, etc.) (2)
CO2 (plus LED) (3)
Fusarium in spinach: Control, management, identification, resistant varieties
Chickweed control (2)
Stabilizing Moveable Tunnels
Inner Covers and Venting (3)
Hardier varieties Cold-hardy lettuces (2)
Automatic opening of internal covers (3)
Harvesting greens
Ideas from the white board:
Soil moisture & irrigation monitoring
Covers/soil/air temp/moisture/plant conditions relationships
Lbs/sqft/unit time
OM+temp+CP2
CO2/lighting/temp for winter growing
winter growing nutrient recs
plastic on beds
Consider on-farm trials and reporting back at another meeting.
Template to share planting dates, days to maturity, etc.
John B – adobe connect presentations, can help people record presentations easily to share
(maybe ahead of time before another mtg). Using the distance learning.
Feedback on this summit?
I learned a pile; it was great perfect size not too big; great size group at least one breakout for
smaller groups to bring back; having smaller breakout group; valuable when one person talked
about one topic they were knowledgable about (3); five minutes with pictures of tunnels, how I
grow; too many sheets to fill in advance; glad it was pulled together fast so I came; great
honored to be here; would like to invite you all up to northern VT during the winter look at
techniques in the field; will be able to use a lot of this in teaching; got a chance to explain why; I
think it was great perfect size, good organization; potential for doing something longterm
important; bigger room and sitting on outside made a difference; I love havinggroup of farmers
talking on one topic; I feel honored and lucky to be here, inspired to keep better records;
suggestion for future: break up into smaller groups, to put together study/research groups;
appreciate depth of conversation; so many aspects of different topics, hope I can continue to
come; breaking down into micro groups and focus on what they know best; more on each farm
to know their system better; great to have people out of our region; technical experts lots of
ideas and takeaways; meeting people. How could we move forward in a meaningful way?
Follow up on things that you really care about. Learning community. Going into literature.
Planting dates: spreadsheet of when we plant, harvest – simple template – fill it out – google
docs – Make chart like in his book on harvest dates to maturity when seeded on different dates.
At different lattitudes. Once we have this info from all the farms we could make maps. We
need to learn how to use the distant learning. Adobe connect record talks. Watch all the talks
before you get there. Bring people from west of Mississippi; even though its very different
climate we could learn.
And Sandy and Elliot are still friends.