University of Illinois Extension
Bruce Spangeberg

These articles are written to apply to the northeastern corner of Illinois. Problems and timing may not apply outside of this area.

Stateline Yard & Garden

Consider Adjacent Plants
When Using Deicing Salts

December 9, 1999

A dusting of snow this weekend reminds us it is December, and significant snows may not be far off. While deicing salts are important tools to help assure safer foot and vehicle traffic in the snow and ice, their use can also damage plantings. Here's my annual column on use of deicing salts and considerations concerning adjacent landscape plantings.

The most common deicing salt material, sodium chloride, damages plants in two ways. Plants may take up chloride from salts accumulating in the soil, which can lead to dieback and decline. Sodium from salts may destroy soil structure, causing more plant problems. Most damage will occur within 30 feet of the roadway or parking lot. Along high-speed roads, salt may also drift onto vegetation, causing "witches brooms," or clusters of twigs at the ends of branches. Evergreens tend to turn brown when salt settles on their foliage.

In residential areas, trees, shrubs, lawns, and other landscape plantings are most often damaged by deicing salts accumulating in the soil, either deposited directly from plowing or through runoff as snow melts in spring. Diagnosing this salt damage can be difficult, as decline, lack of vigor, and many other things could also cause dieback attributed to salt damage. If declining plants are located near sidewalks, roadways, or parking lots, consider deicing salts as a potential source.

Salt damage experienced by plants depends on a variety of factors, including type and amount of salt, timing of application and species of plants. Sodium chloride, although cheaper, is more damaging to plants than sources such as calcium chloride.

Only apply the amount of salt needed to do the job. Mix salt with sand (for traction). Try to shovel or plow before salting. Also, consider where snowmelt goes and vegetation that may be affected when deciding where to pile snow.

Applying gypsum to lawns is sometimes suggested to counteract the salt, but good soil drainage is needed. Typical turf areas near roads, sidewalks, and parking lots are usually have poor soil drainage, limiting the effectiveness of the gypsum.

Along highways, temporary screening may help prevent damage to trees and shrubs. Also be aware of areas prone to salt spray when choosing plant material for these sites so salt-sensitive species are not used.


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