Purdue News

February 12, 1999 Salt can damage plants, expert says WEST LAFAYETTE, Ind. -- Salt spread on roads and sidewalks to melt snow and ice may make driving and walking safer, but it can cause trouble for landscape plants, says B. Rosie Lerner, consumer horticulturist for the Purdue University Cooperative Extension Service. Passing traffic can spray the salt on plants near the road, and homeowners may shovel it onto plants near the sidewalk. Lerner suggested that homeowners who use salt on their sidewalks should not throw snow from the walks onto nearby plants such as shrubs or ground covers. She also suggested using alternatives such as clean cat litter, sand or sawdust to help improve traction on ice. Lerner also suggested protecting roadside plants from getting splashed by traffic by constructing burlap or durable plastic screens. If that isn't practical, she advised using salt-tolerant plants such as juniper, Siberian pea shrub, Russian olive, poplar and honey locust. She said damage can be caused by sodium salts, which are the most common type used for de-icing, and calcium salts, which are used to a lesser extent. "Salts can adversely affect plants in several ways," Lerner said. "Salts deposited on the surface of twigs, branches and evergreen leaves can cause excessive drying of foliage and roots. The salt can be absorbed by the plants and accumulate to toxic levels. Salts can also cause a nutritional imbalance by changing the chemistry of the surrounding soil." The excess salt may cause the plants to be stunted, to grow poorly, or to drop needles or leaves. According to Lerner, the most apparent damage from salts is death of buds and twig tips as a result of salt spray. This may result in the plant becoming too thick, because as the tips of the plants die, the plant responds by growing an excessive number of side branches. Salt accumulation in the soil damages plants more slowly, and the damage may not be noticeable for many months. "Rain or large amounts of snow can help prevent this accumulation by diluting the salt and helping to wash it out of the root zone," Lerner said. "If natural rainfall is scarce, you should consider irrigating these plants." CONTACT: Lerner, (765) 494-1311; e-mail, brl@hort.purdue.edu Purdue News Service: (765) 494-2096; e-mail, purduenews@purdue.edu To the Purdue News and Photos Page