Deicing Salts Harmful to Plants

Deicing salts can save your neck this winter, but they can spell disaster for landscape plants. Whether the salt is sprayed on the plants from passing traffic near the road or is shoveled onto plants near the sidewalk, the salt can cause damage.

Salts can adversely affect plants in several ways. Salts deposited on the surface of twigs, branches, and evergreen leaves can cause excessive drying of foliage and roots. They can be taken up by plants and accumulate to toxic levels. Salts can also cause a nutritional imbalance by changing the chemistry of the soil and can directly harm soil structure.

The most apparent damage from salts is death of buds and twig tips as a result of salt spray. As the tips of the plants die, the plant responds by growing an excessive number of side branches.

However, accumulation damage is more slowly manifested and may not be noticeable for many months. Sodium salts are the most common type used for deicing while calcium salts are used to a lesser extent. Effects usually appear as stunting, poor vigor, die back of growing tips, leaf burn or leaf drop. Winter and spring rains and large amounts of snow, such as we’ve experienced this year, can help prevent accumulation by diluting the salt and helping to wash it out of the root zone. Supplemental irrigation is advisable when natural rainfall is scarce.

Protect roadside plants by constructing burlap or durable plastic screens to shield them from traffic splash. If screening from traffic is not practical, try to use salt-tolerant plants such as Juniper, Siberian pea shrub, poplar and honey locust.

Avoid throwing sidewalk residue on nearby plants, including shrubs and ground cover. Use alternatives such as clean cat litter, sand or sawdust to help improve traction on ice.


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