Early snowfall across portions of Wisconsin last week reminds us that cleaning snow off streets, driveways, and sidewalks will be expected during the winter months ahead. Deicing salts are part of the snow removal process and make travel safer, but keep in mind they also can damage landscape plantings and the environment.

Sodium chloride, an inexpensive commonly used deicing salt material, can damage vegetation in two ways. First, root uptake of chloride accumulating in soils leads to dieback and decline of above-ground plant parts. Sodium can also destroy soil structure conditions, causing numerous plant problems. Plant damage typically occurs within thirty feet of roads, driveways, or parking lots where salts are applied. Second, salt spray drift from roads may drift onto vegetation, causing conspicuous clusters of twigs called “witches’ brooms” on deciduous trees or browning of evergreen foliage.

In residential areas most salt damage to trees, shrubs, lawns, and other plantings is due to salt accumulating in soils. Deicing salts can be deposited directly from plowing or through runoff as snow melts. Damage becomes a chronic issue for plants growing in these soils and is often confused with other causes. If declining plants are located near sidewalks, roadways, or parking lots, consider deicing salts as one potential cause.

Plant damage from deicing salts depends on a variety of factors, including type and amount of salt, timing of application and plant species. Although more expensive, consider deicing salt alternatives to sodium chloride, including calcium chloride, magnesium chloride, or calcium magnesium acetate. Only apply the amount of salt needed to do the job. Salt should be scattered so there is space between the grains. A 12-ounce coffee mug of salt can be enough to treat an entire 20-foot driveway or 10 sidewalk squares. Consider mixing salt with sand for traction, thus reducing the amount of salt used. Shovel or plow as much snow as possible prior to applying deicing salts. Finally, consider where snowmelt goes and vegetation that may be affected when deciding where to pile snow that contains salts.

Along highways or roads where salt spray is likely, temporary screening may help prevent damage to trees and shrubs. Burlap is one material that can be used. Applying gypsum to lawns or soil is sometimes suggested to counteract the salt, but good soil drainage is needed. Often areas near roads, sidewalks, and parking lots have poor soil drainage, limiting the effectiveness of the gypsum.

Looking ahead to future growing seasons, be aware of areas prone to both salt accumulating in the soil and salt spray for new or replacement plantings. Choose plant material with tolerance to salt and be sure to avoid salt-sensitive species. Consult Winter Salt Injury and Salt-Tolerant Landscape Plants for plant lists and more details on this topic.