By Sam Nelson
Landscape Designer, Johnsons Landscaping Service, Inc.
When winter weather transforms your sidewalk and driveway into a dangerous skating rink, how do you melt the ice and snow without destroying your lawn and ornamental plants?
The key is to choose an environmentally safer deicer, use it in moderation and according to instructions, and to apply it before it begins to sleet or snow.
How Chemical Deicers Work
All chemical deicers essentially work in the same manner, by lowering the freezing point of water. The most common ice melter is sodium chloride (NaCl), otherwise known as good old-fashioned rock salt. Its popularity can be attributed to its low price and wide availability. However, since salt water still freezes at 0°F (or -18°C), it is of little help when the temperature falls below this point. Rock salt can also be destructive: it can corrode your car and your concrete walkway, and it can damage or kill your lawn and ornamental plants.
Safer Salts for Your Plants
A better bet is to use one of the alternatives, safer salts on the market. These include Calcium Chloride (CaCl2), Magnesium Chloride (MgCl2), and Potassium Chloride (KCl). In general, these salts are more effective in reducing the freezing point of water to a lower temperature than rock salt, thus making them more effective in colder weather. Moreover, they tend to be less corrosive to metals and concrete, and are safer for lawns and ground-covers. Be sure to carefully look at the manufacturer’s label for the listing of chemicals.
A newer, salt-free melting agent is calcium magnesium acetate (CMA), which is made from dolomitic limestone and acetic acid (the main compound of vinegar). This material has little impact on plants and animals and is a good alternative for environmentally sensitive areas. Pelleted fertilizers containing ammonium nitrate or ammonium sulfate are sometimes also used for melting snow and ice, but these tend to damage concrete more than the salts. For locations where chemical deicers are not appropriate, sand, kitty litter, or gravel can provide some traction, but they will not melt ice or snow.
Always Read the Instructions!
Whatever product you choose, be sure to read the manufacturer’s instructions carefully and do not over-apply. Too many people erroneously believe that if 8 ounces is good, then 16 ounces must be better. Improper use of any chemical deicer may cause plant injury, which appears as drying, stunting, dieback, or “burning” of the foliage.
(Sam Nelson is a landscape designer for Johnson’s Landscaping Service, Inc.)