Its low cost makes it attractive, but rock salt can damage your lawn or garden. Canadians use about five million tons of rock salt each year, but it can harm plants, contaminate water and, in severe cases, sicken or kill wildlife.
When temperatures drop below -9° Celsius, water turns solid and can’t be dissolved by salt. Sand, however, will increase traction—and is garden-friendly. But clean it up properly in the spring, as it can easily clog drains or sewers, and because it absorbs contaminants like oil and chemicals. Gravel is another possible solution.
Though salt remains the most accessible means of de-icing your walkway, other options exist. A rule of thumb: The more eco-friendly the product, the higher its cost will be.
Most combine salt with five other common materials:
- Urea: Also known as carbamide or carbonyl diamide, this de-icer can burn your lawn and garden. Since it’s high in nitrogen it also causes algae bloom in waterways. Should be avoided.
- Calcium magnesium acetate: CMA is a green alternative that is salt-free and biodegradable. But it’s slow acting and only works to about -3° C
- Calcium chloride: It won’t hurt your plants but it can corrode metal and hurt the tender paws of your pets. Works well in cold weather. Don’t track this into your home since it can leave a residue on carpets and shoes.
- Potassium acetate: It’s not that harmful since it is biodegradable, non-corrosive and non-toxic. But it’s pricey and won’t perform well in extreme cold.
- Magnesium chloride: This salt works well in cold weather but use sparingly because too much will make your pavement wet. Can damage concrete.
- Glycols: Ethylene glycol and propylene glycol are both advertised as pet-friendly but are extremely toxic to plants and aquatic life.
Two major considerations
Always keep the minimum effective temperature (MET) of ice melters in mind. If sub-zero temperatures are rare where you live, you don’t need an ice-melter with a MET capacity of -31° C/ -25 ° F.
Use ice melters sparingly; throwing more down won’t melt ice any faster. And don’t shun the greenest method of snow and ice removal: shoveling. De-icers can’t melt through compacted snow or built-up ice, so the less there is, the more effective they’ll be.