Robert Bishop 
Frederick County Master Gardener Program

Now is the time to stock up on ice melting products before you actually need them. It is also a good idea to keep a small bag in the trunk of your car in case you get stuck on an icy parking lot or side street. There are many products available and understanding the differences between them will help you choose the best one.

Ice melting products work by first attracting moisture and forming a liquid, then as the liquid flows over and under the ice it causes it to melt. The rate of melting depends on how fast the chemical reacts to the existing moisture. When temperatures drop there is less water available and melting is slowed or inhibited. All products will have some effect on the environment.

The two most commonly used and inexpensive materials are Rock salt ( sodium chloride, NaCl) and calcium chloride (CaCl₂). They melt ice over the broadest temperature range and are the only materials effective below 20F. Sodium chloride will work down to 15F, and calcium chloride to 5F. Both are very corrosive and can damage lawns, trees and shrubs.

Ice melting materials that are less corrosive are: urea (fertilizer), potassium chloride (KCL), and calcium magnesium acetate (CMA). These materials are only effective down to 20F and are more expensive. The least effective of the three is the urea. This is a fertilizer and is required in large amounts to melt ice and therefore has the potential to pollute surface and ground water. The Maryland Cooperative Extension does not recommend using fertilizers for ice melting.

Often products contain combinations of the above materials along with an aggregate like sand to aid traction. These products are effective over the entire range of temperatures while offering reduced environmental impact. Check the label to be sure of the contents of the package.

Ice melting products are best applied prior to ice formation. They should be spread thinly over the entire surface. If thick ice has formed in very cold weather add some water to the product to initiate melting. Remember it is the chemical solution of the water and the material that does the work. Avoid using these products on concrete less than 1 year old, brick and stone sidewalks, and other surfaces in poor condition. To provide a safe footing use sand or cat litter alone on these surfaces.

Damage to plants occurs from the runoff solution created when using these products. Salt damage becomes more evident in spring. Look for a browning of the foliage, stunted growth and sections that die back, especially along walks, driveways, and roads. If you suspect salt damage have a soil test done. Flush the affected area with plenty of water in the spring, 3 - 4 inches applied in 1 inch applications. Gypsum can be added to the soil to reduce sodium levels.

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