Salt damage to the lawn and plants along the drive

Rock salt, or sodium chloride, is the most common deicer and does the most harm to plants. Salt reaches them three ways. Cars passing on a salted road throw spray onto buds, needles and stems. Salty meltwater soaks into the soil. And salt-laden snow gets shoveled or plowed onto lawns and beds.

What salt does

• Burns foliage. Spray burns buds, leaves and small twigs, and dries out the bud scales so the leaves and flowers inside die in the winter wind. Evergreens suffer most.
• Dries out roots. Salt in the soil holds onto water, so roots can't take up as much. Plants go thirsty even in moist soil.
• Starves the plant. Sodium and chloride crowd out potassium and other nutrients, and chloride can build up in leaves to toxic levels.
• Packs the soil. Sodium makes clay particles swell, which compacts the soil and slows drainage, so roots grow poorly.

Damage often doesn't show until late winter or spring. Deciduous plants show it when they leaf out. Soil damage can take until summer, or even years, to appear, and often shows up in hot, dry weather.

The signs

• A strip of thin, stunted or dead grass along the walk, driveway or street in spring
• Needles browning from the tips, or leaf edges scorched brown
• Damage mostly on the side of a shrub or tree that faces the pavement
• Dead buds, twig dieback and late leafing out
• Fewer or smaller leaves, and early fall color or leaf drop

A soil test can confirm a salt buildup.

Using less salt

• Clear snow early and often. Shovel, scrape and sweep before ice forms, so less salt is needed.
• Use only a little. About 12 ounces, roughly a coffee mug, covers 1,000 square feet, about a 20-foot driveway. Spread it with about 3 inches between grains, and only on the paths that need it, not on snow.
• Sweep up leftovers. Grains left on dry pavement wash or blow into the plants. Save them for the next storm.
• Add grit. Sand, ashes or kitty litter give traction without melting anything.
• Not all deicers are alike. Calcium chloride, magnesium chloride, potassium chloride and calcium magnesium acetate do less damage to plants than sodium chloride.

Protecting the yard

• Keep salty snow off the beds. Pile shoveled snow away from shrubs. Salt in it harms them, and the weight can break branches.
• Watch where the meltwater runs. Salty runoff collects where melt naturally flows, so keep new plantings out of those spots.
• Shield shrubs from spray. Burlap, plastic or wood barriers block spray from the street.
• Leave room. Plant trees and shrubs at least 3 feet from salted walks and drives, and at least 7 feet from a salted road. Evergreens don't belong along salted surfaces.
• Grow salt-tolerant grass by the pavement. Fine fescues hold up best in salty soil, tall fescue is in the middle, and Kentucky bluegrass does poorly. Perennials that die back over winter and annual flowers also do well along drives and walks.

Repairing the damage

Soak the damaged area with 1 inch of water, three or four times in spring, to wash the salt below the roots. Leaching works only in soil that drains well. Adding organic matter improves poorly drained soil. Gypsum can lower high sodium left by heavy rock salt use. In a small bed, replacing the soil is an option.

An annotated example

What to do next

Use a mug of salt per 1,000 square feet and sweep up what's left. Pile shoveled snow away from beds and shrubs. In spring, soak any brown strip along the pavement with an inch of water three or four times.