Q: During the cold seasons we deal with icy walks and driveways and worry about the potential damage to our lawn and landscape plantings from deicing agents. What can we use that is safe and effective?
A: The safety of both residents and visitors requires that we deal with icy surfaces around our homes, but chemical deicing agents can damage plants as well as concrete and other masonry. A strategic approach to ice prevention and removal must balance safety with plant protection and cost.
Begin with preventive measures. Arrange downspouts and landscape grades so that they do not spill water onto walks or drives, pitch pavements to drain rather than pool meltwater, and expose pavements to as much winter sun as possible.
Remove snow before it melts and refreezes, or is trampled into a frozen sheet. A thin layer of snow on nearly bare pavement will melt rapidly in direct winter sun, even when the air temperature is below 32 degrees Fahrenheit. When removing snow from previously treated surfaces, spread it around to dilute the concentration of any remaining chemicals.
Sand can improve traction on compacted snow or ice. It will not harm plants, but it does not speed melting and the residue must be cleaned up in the spring.
Four chemical melting agents readily available to homeowners are described below. Each poses a different degree of danger to plants, with the safest also being the most expensive.
- Sodium chloride (NaCl) is the most common and least expensive deicing compound. It is most effective when temperatures are above 15 degrees. It is highly corrosive, can damage plants, and is detrimental to soil structure at high levels.
- Calcium chloride (CaCl2) acts quickly, is effective in extremely cold temperatures (below 20 degrees), and leaves no visible residue. It is slightly less damaging to plants than sodium chloride, but is highly corrosive to concrete and metals.
- Magnesium chloride (MgCl2) is also less damaging to plants than sodium chloride and is effective to 5 degrees, but it is also corrosive.
- Calcium magnesium acetate (CMA) is a salt-free deicing compound. It is effective to 20 degrees, causes little or no damage to plants, and is less corrosive than the other chemicals. It is, however, more expensive.
In summary, take preventive measures and remove snow when and where possible, minimize the use of chemical melting agents to prevent damage to both plants and pavement surfaces, and always read and follow the manufacturer’s instructions.
Please contact Plant Information Service at Click here to show mail address or call (847) 835-0972 on Wednesdays and Thursdays between 10 a.m. and 2 p.m. with additional questions.