Make Your Own
Lettuce ”Machine”
Saturday 2/11/17 4:30 PM
2017 WPT Garden Expo
Make Your Own Lettuce “Machine”
Description:
Introduction to a Do It Yourself, small footprint
application of Kratky Hydroponics. Complete
explanation of how you can create your own
Lettuce “Machine” to grow salad greens without
soil year round, a discussion of the supplies
you need and the effort involved.
What does that mean?
Year Round: Yes. Grow and Harvest In Winter.
Also an alternative to sweating in the summer.
You can Do It Yourself: Just follow instructions.
Small Footprint: Scalable to ANY size.
From a single plant to any # of plants.
What does that mean?
Hydroponics: No Soil.
You Control the pH and Nutrients.
You also control the :
- Temperature / Water
- Insects (no aphids)
Kratky Hydroponics: No Moving Parts.
“The only moving part is the lettuce.”
The Goal . . . Fresh Salad Greens . . . Now
Presentation Schedule
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5 min: The Lettuce “Machine”
Concept/Process
5 min: Step 1: Soaking
5 min: Step 2: Sprouting
5 min: Step 3: Growing
5 min: Step 4: Harvesting / Cleaning
10 min: Variations on the Lettuce “Machine”
5 min: Effort Involved/How to Run It
A Simple Lettuce “Machine” - Pill Bottles
A Simple Lettuce “Machine” - Pill Bottle
The Lettuce “Machine” Process
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Step 1: Soaking the Seeds
Step 2: Sprouting the Seeds
Step 3: Growing in the Lettuce “Machine”
Step 4: Harvesting the Lettuce
& Cleaning the “Machine”
Step 1: Soaking the Seeds
● Used seeds for Microgreens and Sprouting
● 80,000 seeds for $10.45
● Red Romaine, Green Romaine, Freckles, Red Leaf,
Arugula, Mizuna.Tatsoi, Pepper Cress, Red Russ. Kale
● 5-10 seeds per cup in 1/2 “ to 1” Water
● Spread Seeds using a Baster
● Soak for ½ to 1 day in cool dark (65 deg
F+/-)
Step 1: Soaking the Seeds
● Same as the first step in growing sprouts
● Use clean seeds or clean them
● Soaking > a day will result in “sprouts”
making it harder to distribute them using a
baster.
● Using a baster is easier then counting the
seeds by hand. You never touch the seeds.
Step 2: Sprouting the Seeds
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Clay balls in net cups
Spread seeds using baster
Stand in ½” to 1” clean water for 7+ days
Clay balls: 2 lbs for $8.90 - reusable
Net cups: 2” , 50 for $9.94 - reusable
Sprout under grow lights for 7+ days
Until roots reach bottom of net cups.
Step 2: Sprouting the Seeds
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Clay balls are porous and absorb water.
Also referred to a Hydroton Pellets.
Spherical, the size of a small marble.
Also used in soil mixture to improve aeration.
Step 2: Sprouting the Seeds - Exploded
View
Step 3: Growing in the “Lettuce” Machine
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Transfer sprouts in net cups to containers.
Containers hold nutrient solution.
Containers exposed to grow lights.
Net cups rest in holes in container.
Bottom half of net cup in nutrient solution.
Roots grow down & the solution level drops.
2” net cup fits in a 2” circular diameter hole.
Step 3: Growing in the “Lettuce” Machine
● An air gap is created above the solution.
● The roots in the air gap form air roots.
● Roots take in oxygen along with the
nutrients.
● The only moving part is the Lettuce.
The Lettuce “Machine” - Sprouting and Growing
The Lettuce “Machine” - with 3 containers
The Lettuce “Machine” - With 5 containers
The Lettuce “Machine” - Covered w.out Sides
The Lettuce “Machine” - Covered
The Lettuce “Machine” - w. Fabric Sides
The “Engine” - Growing Containers
Growing Container - Supplies
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Light proof material
2” diameter circles for 2” net cups
Tall / narrow is better than broad / shallow
Allows an air gap to form, healthier roots
2” circular drill bit with electric drill
Growing Container - Purpose
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Holds the nutrient solution
Suspends the net pots in the solution
Can be variety of sizes/shapes
Trade off between Volume to hold enough
solution and Height to allow for the air gap
The Lettuce “Machine” - The “Frame”
The “Frame” - Holds the Growing
Containers
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Contains the growing containers
Eliminates impact of insects (aphids)
Top is clear food wrap & allows light in
Side is fabric and allows air in
Acts as a mini-greenhouse
The “Frame” - Holds the Growing
Containers
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Bussing Tubs (21.5” x 17.1” x 7”)
Steam Table Pans (19.6” x 11.6” x 3.2”)
Carriage Bolts/Nuts/Washers (6” x .25”)
Clear Food Wrap (12” x …) and Tape
Scissors / Awl / Round FIle
Fabric / Clothes Pins
Making A Basic Lettuce Machine
Let’s Make One.
Effort Involved (per month)/ How to Run It
10 minutes
Clean the “Machine” / Prepare Net Cups
5 minutes
Distribute seeds to soaking cups
1 day
5 minutes
Plant the seeds in Net Cups
7+ days
5 minutes
Sprout the seeds in Net Cups
Put Net Cups in the “Machine”
3+ weeks
5 minutes
Soak the seeds in soaking cups
Grow the Lettuce
Harvest the Lettuce
Comments / Considerations - Varieties
● Red Romaine, Green Romaine, Freckles, Red Leaf,
Arugula, Mizuna.Tatsoi, Pepper Cress, Red Russ. Kale
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Sold as a package for growing microgreens
● Need to try others
Comments / Considerations - Nutrients
● Dry powder: 6 macro and 5 micro nutrients.
● Mixed in Water.
● Keep pH of the solution in the 6.0-6.3 range.
https://5gallonbuckethydro.wordpress.com/lettu
ce-greens-and-herbs-nutrients/
Comments / Considerations - Nutrients
Potassium, Calcium, Nitrogen, Phosphorous,
Magnesium, Sulphur, Iron, Manganese,
Boron, Zinc, Copper, Molybdenum
Comments / Considerations - Lighting
● Bulb lights with with round metal reflectors
3-4 lights per Lettuce Machine
CFL : 6500K / 1450 Lumens / 23W(100W)
CFL : 6500K / 800 Lumens / 9W(60W)
CFL : 6500K / 1600 Lumens / 23W(100W)
LED : 5000K / 1100 Lumens / 12W(75W)
LED : 5000K / 800 Lumens / 8.5W(60W)
LED : 5500K / 750 Lumens / 9W(60W)
Fluorescent characteristics may change over time.
Comments / Considerations - Lighting
● Tube lights with with metal reflectors
Cover two Lettuce Machines.
T5 Fluor: 4’ / 6400K / 5000 Lumens / 54W
T8 LED: 4’ / 5000K / 2200 Lumens / 17W
(reflector holds two tubes)
Fluorescent characteristics may change over time.
Comments / Considerations - Lighting
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Grow light with timer supplements window light
Available as CFL bulbs or tubes
K(Color Temperature) Common is 6,500
Lower will be “Redder” higher will be “Bluer”
After seeds sprouts keep lights within a few inches
Without enough light, plants will become spindly
Depending upon available sunlight, supplement with grow
lights. Plants do need down time as well
Comments / Considerations - Lighting
● Sunlight is composed of
“all the colors in the rainbow”
● The Green is reflected
● The Blue and Red are absorbed
Comments / Considerations - Lighting
Comments / Considerations - Water
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You can test the pH of the nutrient solution
Adjust the nutrient solution by adding a pH modifier
City water may have chlorine or other
You can use filtered water
Solubility of nutrients in water is a function of pH.
Nutrients dissolve in water & taken up through the roots
The pH impacts the solubility of various nutrients
There are recommended pH ranges for many plants
7.0 is neutral, <7.0 is acidic, >7.0 is alkaline
Comments / Considerations - Roots
Comments / Considerations - Roots
● Healthy roots are white
● The roots will become dense in the air gap
● Without a large enough air gap the roots will
be spindly
● Keep the container clean
● Keep everything clean
Temperature of Nutrient Solution
Temperature for nutrient solution is from 65-70 deg. F.
Another source said 75 deg. F.
Trade off between the ability of the water to absorb oxygen
vs the ability of the water to dissolve the nutrients.
The warmer the water the less oxygen it can hold.
Roots need oxygen.
The cooler the water the less the nutrients can dissolve in
it.
The plants need nutrients.
Questions?
Contact for More Information
[email protected]
Kratky article:
http://www.ctahr.hawaii.edu/hawaii/downloads/Three_Non-circulating_Hydropo
nic_Methods_for_Growing_lettuce.pdf