Davis: Avoid dangers to landscape plants from de-icing salt

It appears the groundhog has seen its shadow. Whether you think that this means six more weeks of winter or you wish someone would just make a pot of stew, the recent weather certainly reminded us that winter is not over yet.

It is not uncommon to have snow and ice in February. It also isn’t uncommon to have a few days or even longer periods of spring-like temperatures as well.

This week’s winter weather reminded me of an issue that impacts landscapes every single year. Homeowners should be aware that de-icing salts applied to sidewalks and streets during winter weather events can potentially injure landscape plants. There are some steps that can be taken in winter weather to avoid damaging plants.

The biggest danger from de-icing salts comes when they are over used, or applied in extra heavy doses. There are six main types of de-icing products: calcium chloride, rock salt, magnesium chloride, potassium chloride, urea and a newer one called calcium magnesium acetate. All of those can be harmful to landscape plants and grasses in some instances, and some of these treatments are more harmful than others.

Salts can injure plants in several ways. The chloride ion is considered the most toxic element of deicing salts. It causes much of the direct plant tissue damage. When salt sprays from puddles onto plants as cars drive by, it may scorch leaves or kill buds and twig tips on deciduous plants.

Salts applied during late spring snow storms are the most likely to cause damage. Pines in general are especially noted for their sensitivity to roadside deicing salts. When affected, pine needles may become pale green, yellow or brown in late winter.

Dying vegetation on the side of plants facing the road, driveway or walkway may indicate that the damage could have been caused by salt spray. Accumulation of salt in the soil also makes it difficult for plants to grow properly.

There are a few things that you can do or should know in order to avoid damaging your landscape plants with de-icing salts.

— Avoid using deicing salts in areas where more sensitive landscape plants are located.

— Shovel snow or ice before it becomes compacted from traffic, and allow the natural heating from solar radiation to melt the rest of the driveway off if possible without using deicing salts.

— Use alternatives to deicing salts such as sand to increase traction in driveways and on sidewalks.

— Make sure to read the label on deicing salts before purchasing or applying them to see if they are known to be more or less harmful to the landscaping.

— Always apply salts according to the labeled directions, and minimize applications when possible.

— When shoveling or scraping driveways where deicing salts have been used, do not shovel snow and ice into flower beds, or pile it up near landscape shrubs.

David Davis is a Clark County Cooperative Extension Service Agent for Agriculture and Natural Resources.