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.
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.