Post Sandy Garden Considerations
Bruce Crawford
Director, Rutgers Gardens
Charlene Costaris – a special thanks to
March 11, 2013
Rutgersgardens.Rutgers.edu
How salt damage occurs
Two main routes
1. Root damage. Salt water draws water out of root through a process called osmosis. Water
travels from inside the cell or the area of lower sodium concentration to outside the cells in an
attempt to balance or make the concentrations equal. As the plant cell loses water and the salt
concentration gets too high inside the cell, the cell dies. Roots may die
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Longer it lasts, more damage
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Plant suffers drought, even in moist soil. Due either to the damaged root or the high soil
salt interfering with how the plant absorbs moisture.
2. Foliar Damage. The Chloride ion moves into plants and becomes concentrated in the leaf
margins and in the tips or terminal buds of branches. This ion is carried in the vascular system
into the leaf and as the water evaporates out of the leaf, the Chloride ion is left behind. When it
reaches a high enough concentration, it kills the cell. Because the leaf veins branch finer and
finer toward the edge of the leaf, the highest Cl concentration will end up toward the edge of the
leaf, allowing the edge and tip to burn.
It can also be absorbed by the leaves if a salt mist coats the foliage. This results in:
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Necrosis of the leaf margins
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Die back of branches and the sprouting of axillary and adventitious buds
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In addition, people that lived with 10 miles or even more of the shore have witnessed
tremendous damage to their plants from salt spray, which was blown in from the ocean.
The salt in the spray is the same as common table salt or Sodium Chloride (NaCl).
Salt raises the pH
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pH affects nutrient availability.
High sodium levels compete with the absorption of other nutrients.
High salts hardest on germinating seeds and seedlings.
You know the pH sweet spot for most garden plants is 6.0-6.5, and for many natives it is even
lower, 5.0 – 5.5. As the pH rises, availability of iron, manganese, boron, copper and zinc drops
off.
Excess sodium competes with the uptake of other nutrients, most notably calcium. The plant
takes up too much sodium and not enough calcium.
Don’t really know why high salts are hardest on seeds and seedlings, but reliable sources say so,
and it seems easy to understand. I suppose just because they’re tiny and tender
Salt Destroys Soil Structure
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Not a problem in sandy soil.
o Lack of complex soil structure as it is mostly single grains.
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Problems arise in organic or clay soils. This include
o Alluvial soils along rivers
o Clay soils
o Soils improved with organic matter
The salt interferes and destroys the bonds that hold soil particles together and creates the soil
matrix. The pores of the soil become filled with finer materials, preventing the soil from
draining properly and holding nutrients. Visually, the soil no longer is friable or crumbles, but
appears like mud and water does not readily drain through.
Plant damage is impacted by:
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Rainfall before flooding, since the salt water floats on top of fresh water. In other words,
if the soil is saturated with fresh water, the salt water can not readily soak into that soil.
Conversely, the longer that the wind pushes the salt water onto mainland, the greater the
chance that it will slowly penetrate the soil.
Time of year. Plants subjected to salt during the dormant season are not actively growing
and transpiring and have less damage while those subjected during spring and summer
have far more damage since they are actively growing.
Plant tolerance. Some plants are more tolerant of salt water flooding and salt spray than
others. Again, you can make up reasons like thicker wax coating on leaves and you can
see that plants with naked buds burn easier than those with bud scales, but nobody knows
the full “why”, so far as I know.
What to do
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Remove piled-up sand, but most obviously be careful of the plant!
Lawns, use hose and a spring rake to get mud and debris off surface
Irrigate as soon as possible. The best time to rinse the salt out of the soil is immediately
after the water recedes. But later is better than never! Rain and snow also rinses out salt.
6” of irrigation/rain removes 50% of salt
12” reduces salinity by 80%
24” reduces salinity by 90%
Be careful not to let water sheet flow across the soil, but move down through the soil to
carry the sodium with it. You want the sodium to move at least below the root zone or
about 8 inches to a foot deep..
The more time that the salt remains in the soil, the more damage to the roots. Obviously,
there’s an unknown point beyond which the damage is too extensive for the plant to
recuperate – this point varies from species to species.
Use Gypsum or Calcium Sulfate (CaSo4). What does Gypsum do?
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Removes sodium from the soil. Gypsum replaces sodium ion on soil particles with
Calcium
o 50 lb./1000 sq. ft. in sandy soil
o 100 lb. or more/1000 sq. ft. in heavier soil. It takes more gypsum in clay or
loamy organic soils because there are a lot more tiny particles, therefore a lot
more surface you’re trying to “coat” with the gypsum
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Spread, till and irrigate. Gypsum will work best and fastest if it can be thoroughly mixed
with the soil so it’s in fast contact with the soil particles
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Can’t till? Spread in smaller doses and irrigate.
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Gypsum does not raise the pH
Reduces root damage
Improves soil structure and function in clay or organic soils
Add organic matter
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2 -4” of leaf compost, tilled in to a depth of 6” or greater if possible
Increases drainage
o Helps move sodium down and out of the root range
Improves structure of soil. There are areas where tilling in compost is simply not an
option. Use organic mulches, especially shredded leaves. A certain amount of organic
materials will be carried into the soils by frost and insects.
Do not
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Lime the soil without a soil test. Lime should never be applied without having a soil test
completed first. It’s especially important after salt water inundation, since the salt raises
the pH and liming the soil will push the pH even higher. This pH will gradually drop as
the salt is leached out of the soil, which is why, one should wait until near planting time
to do soil testing in order to get as accurate a reading as possible.
Apply fertilizer Fertilizers are salts and it may make burn worse. We all want to reach
for the fertilizer bag to try to fix things, but we should resist the urge. Adding more salt
to the soil may just be stressing the plant and killing more roots. Wait for next spring and
see how the plants are growing. Fertilize, if necessary, in small amounts during periods
of active growth and not after July 15.
Make snap judgments
o The plant may not be dead
o Wait to see growth next season.
Pruning
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Do not prune until next growing season. It may not be as damaged as it appears.
o New leaves may appear normal, or more likely they may be small and lightyellow.
After the foliage flushes, only remove dead branches and shape the plant.
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The plant needs as many leaves as possible in order to produce the necessary sugars to
recover from the damage.
Turf
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Is it dead? Dig out a core, pot it up and bring it indoors to see if it responds.
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Does it grow? Set the pot in a sunny 65-75 degree spot and keep it evenly moist. If it is
alive, green shoots will start to show within two weeks.
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More susceptible to salinity:
o Most Kentucky Bluegrass selections
Moderately tolerant of salinity:
o most fine fescue, some bluegrass
Most tolerant of salinity:
o Tall fescue, perennial rye, creeping red fescue and Zoysia. Zoysia is green only
during the warmth of summer and is straw colored during the cooler season. It can
also be invasive but it is rather salt-tolerant. Zoysia is planted by plugs and will
take 3 years or so to cover the ground. Once it is established, it’s very vigorous
and invades beds and borders and potentially neighbor’s lawns.
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Soil test before replanting
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Test for soluble salts.
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Test close to planting season, since the salt level will slowly decline over time with
rainfall.
The soil test will tell you all the usual good stuff, but there are two main things now:
1. pH, important because salt water flooding raises the pH and it may be too high. If so, you for
sure don’t want to add lime. The soil may even need to be acidified with sulfur to lower the pH.
2. soluble salts, important because it gives you an idea or whether there’s still too much salt in
the soil. Do the test close to planting time because the salt level is dynamic—every rain or
irrigation with fresh water will lower the salt level, and every salt water flood will raise it.
If people want to do a quick and dirty test, they could put some soil in a pot and plant vegetable
seeds to see how they do. Bean, turnip and radish are characterized by Knott’s Handbook for
Vegetable Growers as sensitive to salt in the soil.
In terms of growing vegetables in salty soil, zucchini, beet and broccoli show least (9%)
reduction in yield for each unit salt increases above the threshold where they begin to be
affected.
What to do this summer
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Most important, remember the root damage as plants will suffer greatly during a
drought.
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Keep the root zone evenly moist, remembering that the roots extend beyond the drop
line.
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Only fertilize if clearly necessary. If the trees put on 6”-12” of growth, they are doing
well.
o Use a half-rate and repeat
o Not after July 15
Don’t drown them with kindness. Most plants will be happiest with the same 1-1½ inches of
water per week that also includes rainfall. More is not better, unless they’re still leaching out
salt. Apply in two doses about every 3 days.
Trees
Superstorm Sandy has had a tremendous impact upon the opinion of shade trees as an asset for
NJ residents. Up until October, homeowners considered them a great asset. They cooled homes
during the hottest days of summer through the casting shade upon their home and through the
cooling action of water evaporation; they helped the environment by reducing our carbon
footprint by tying up CO2 for well over 100 years; and they provided a perception of depth
through the placement of a trunk between the viewer and the homestead. A home with a
majestic old shade tree was considered to be far more desirable than a home located on a barren
lot of turf. Subsequent to Sandy, many NJ residents now look at trees as a tremendous liability.
Thoughts to consider before replanting:
Trees that are planted now will be impacted most greatly by climate change in the future. Some
of these changes will most likely include:
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More prolonged summer periods when the temperatures are near or above 100.
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Longer autumns and later springs.
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Warmer average winter temperatures, but, NJ will still experience winters with
temperatures similar to those in years past. Planting only more Southern and less hardy
plant species is not good option.
Evergreen Trees
Chamaecyparis thyoides (Atlantic White Cedar)
Ilex opaca (American Holly)
Juniperus virginiana (Eastern Red Cedar)
Magnolia grandiflora (Southern Magnolia)
Thuja occidentalis (Arborvitae)
Deciduous Trees
Amelanchier canadensis (Serviceberry)
Lagerstroemia x ‘Natchez’ (Crapemyrtle)
Lagerstroemia fauriei (Crapemyrtle)
Magnolia virginiana (Sweetbay Magnolia)
Nyssa sylvatica (Black Gum)
Quercus bicolor (Swamp White Oak)
Sassafras albidum (Sassafras)
Evergreen Shrubs
Ilex glabra (Inkberry)
Juniperus species, particular Juniperus conferta (Shore Juniper)
Myrica pensylvanica (Wax Myrtle)
Deciduous Shrubs
Baccharis halimifolia (Groundsel Bush)
Clethra alnifolia (Summersweet)
Prunus maritima (Beach Plum)
Rhus spp. (Sumac)
Rosa rugosa (Rugosa Rose)
Vaccinum corymbosum (Highbush Blueberry)
Evergreen Groundcovers
Arcostaphylos uva-ursi (Bearberry)
Juniperus conferta (Shore Juniper)
Lirope spicata (Creeping Lilyturf)
Opuntia spp. (Prickly Pear Cactus)
Sedum spp. (Sedum)
Deciduous Groundcovers
Hemerocallis (Daylily)
Stachys byzantina (Lamb’s Ear)
Thymus praecox (Creeping Thyme)
Flowering Perennials
Aquilegia canadensis (Columbine)
Aster novae-angliae (New England Aster)
Baptisia australis (Blue False Indigo)
Nipponanthemum nipponicum (Montauk Daisy)
Perovskia atriplicifolia (Russian Sage)
Rudbeckia spp. (Black-eyed Susan)
Solidago sempervirens (Seaside Goldenrod)
Yucca filamentosa (Adam’s Needle Yucca)
Ornamental Grasses
Ammophila breviligulata (American Beachgrass)
Calamagrostis acutiflora (Feather Reed Grass)
Carex flaccosperma (Blue Wood Sedge)
C. grayi (Gray Sedge)
Muhlenbergia capillaris (Muhly Grass)
Panicum virgatum (Switchgrass)
Schizachyrium scoparium (Little Bluestem)
Sorghastrum nutans (Indiangrass)