Slick sidewalks and roads are hazardous. Common de-icing compounds like calcium chloride, sodium chloride (rock salt), potassium chloride (muriate of potash) and urea fertilizer can make ice removal easier but they can also damage your landscape when present in large amounts. Salt and fertilizers in de-icing compounds can cause stunting, leaf burn, “witch's broom” and root damage in turf, ornamental shrubs and trees. Although salt is applied throughout the winter, most salt damage occurs in late winter and early spring when plants are beginning active growth and excess salts are pulled into the plant.
High salt levels also change the structure of soil in runoff areas, causing it to become compacted, restricting nutrients, water and oxygen availability to the plants. Accumulation of salt in the soil over several years may cause progressive decline and eventual death of plants. If you suspect an area in your yard to have high salt levels, a soil analysis should be done to determine the actual salt levels present.
Alternatives to tradition de-icing compounds include a new salt-free melting agent called calcium magnesium acetate (CMA). CMA is made from dolomitic limestone and acetic acid (the principal component of vinegar). Studies have shown the material has little impact on plants. Sand and sawdust are also good alternatives to salt for improving traction in slippery surfaces.
To protect plants from direct exposure to the spray of salty slush during snow removal, cover them with burlap cloth. Salt tolerant plants should also be planted near the street to block exposure for more sensitive plantings. In runoff areas affected by high salt levels, flushing the soil with 2 inches of water over a two to three hour period in early spring will help leach much of the salt from the soil. Repeat this procedure three days later. Plants that are particularly sensitive to salt damage include redbud, hackberry, hawthorn, crab apple, pin oak, red oak, littleleaf linden, barberry, boxwood, dogwood, spirea, viburnum, red pine, white pine, Scotch pine, yew, arborvitae and hemlock. Salt tolerant plants should be planted near the street to block exposure for more sensitive plants. A partial list of salt tolerant plants includes Amur maple, artemesia, common lilac, Japanese tree lilac, forsythia, Van Houtte and rroebel spirea, shadblow serviceberry, and snowberry.
Ray Ridlen is an agriculture/horticulture educator for the Oklahoma County Extension Service. His column addresses frequently asked horticulture questions. For more information, call 713-1125.