Salt damage on landscape plants
Salt use in winter can lead to weakened and damaged plants come spring time.
Icy winter conditions increases the use of salt to melt ice on roads and sidewalks, which can lead to damage of ornamental plants adjacent to these areas. Salt damage occurs on plants where spray mist from passing cars coat the leaves and buds and where large concentrations build up in landscape beds adjacent to sidewalks and driveways.
Sodium chloride, the most commonly used deicer, damages plants from roadside mist by desiccating the bud scales of plants exposing tender tissue under these scales. The immature leaves and flowers left unprotected by bud scales begin to dry out and are often killed. Sodium chloride from sidewalk salt that builds up in the soil around plants dissolves in water, creating separate ions of sodium and chloride. Sodium ions reduces root uptake of necessary plant nutrients, such as potassium, calcium and magnesium. Chloride ions are moved into the plant and accumulate in leaf tissue where it interferes with photosynthesis. The salt in the soil also can dehydrate the plants as it pulls water away from roots. Sensitive plants like white pines, roses, rhododendrons and yews can become weak, stunted, have dried out foliage and in cases where salt use is very high, plants may die.
What can be done to prevent damage to landscape plants? Alternative materials can be used around sensitive plants, such as coarse sand providing traction on ice and de-icing products like calcium chloride or calcium magnesium acetate. Both types of calcium de-icing products are safer to use around plants, but are more expensive.
Spring rains will help to flush soil of salt, but if conditions are on the dry side it may become necessary to protect plants by watering sites to reduce salt levels. Barriers can be placed around susceptible plants with stakes and burlap cloth to prevent splashing and drifting mist along the edges of roads.
Use of salt-tolerant plantings may be the most logical solution since it’s helping to reduce the cost associated with replacing damaged plants and reduce the use of more expensive de-icing products. Protecting the public from icy road and sidewalk conditions is a necessity in Michigan. Landscape designs should anticipate the use of salt in areas adjacent to roads and sidewalks incorporating species that are tolerant of salt.
For a list of landscape plants describing their tolerance to salt, visit Salt Damage in Landscape Plants by Purdue Extension. More information on salt damage can also be found by reading Salt damage and warranty issues by Bert Cregg on MSU’s IPM web site.