The Road Salt Assault on your Plants
If you’ve ever had to make a precarious trip across an icy patch of sidewalk, or have had to drive over snowy and icy roads, you know the value of road salt and ice melt products during cold, northern Virginia winters.
However, use of these products can harm nearby living things, including your plants, trees, pets, and the local ecosystem.
How Salt Harms Plant Life
The most common type of ice melting agent is rock salt (sodium chloride), though you might also see ice melt products made of calcium chloride, magnesium chloride, or potassium chloride.
Salt can be incredibly dangerous to plant life. Plants normally need only a tiny amount of sodium for optimal health. But when large quantities of salt seep into the ground, it stops plants from taking up other nutrients, such as potassium and calcium, leading to unhealthy plants.
Even in smaller amounts, rock salt and other ice melt products are harmful to plants. Once salt is dissolved in water, the sodium and chloride ions separate, and the chloride is absorbed by the roots and brought up into the plant. The salt pulls moisture out of plants, including any moisture in the leaves, branches, roots or main stems of your shrubs and trees. In this condition, plants may not be able to draw in water, even if the ground is well watered. This is often the cause of the brown, dry leaf tips and dying leaves you may see on evergreens in winter or on new leaves in spring (this is called leaf scorch), as well a shriveled, dead shrubs and trees.
Alternative ice melt products also cause extensive damage, although they may not be quite as destructive as rock salt. The chloride salts in any of these ice melts are corrosive and toxic, often killing most of the plant life close to roads or driveways where used.
The Problem With Road Salt & Ice Melt Products
The main problem is that road salts and ice melt products dissolve as the snow melts, traveling into the soil where the roots of plants and trees absorb it. Anything planted near areas that are treated with salt or ice melt is at risk of damage from these dissolved salts.
Spray from nearby roads can also cause the salt to land on branches and the leaves of evergreen trees and shrubs, drying them out on contact, damaging the leaves, and making the plant less cold hardy and more likely to freeze.
How Road Salt Harms Pets and Humans
Both sodium and chloride are irritants and can hurt a pet’s paws. If a dog or cat ingests any of the ice melt products, whether from eating polluted snow, drinking from contaminated puddles or licking their paws, it can cause vomiting and diarrhea. Ingesting too much sodium chloride results in death (and it doesn’t take much, a four-pound dog would need to only about 2 ounces for it to be fatal).
There are pet safe versions of ice melt that do not contain sodium or chloride and are usually urea-based. These break down into a nitrogen-rich fertilizer, but too much can still cause problems to plants.
Too much exposure can even harm humans, causing burns or blistering if the ice melt soaks through clothes. The poison control center contains a story about a man who was kneeling on ice melt covered roads. The product soaked through his clothes and he ended up in the emergency room with burns and blistering on both knees.
Keep in mind that all of that salt has to go somewhere, so it is affecting groundwater and waterways. Studies are being done to ascertain the negative effects that this may have on rivers, fish, soil quality, and more.
Alternatives to Using Rock Salt
- Try to remove the snow and/or ice before it settles and becomes more difficult to shovel. This may allow you to forgo using any kind of salt or ice melting product.
- If you’re expecting snow or ice, spread a light application of ice melt product before the weather arrives. This will minimize snow or ice build-up and make it easier to remove afterward.
- Ice melt has no effect on light, fluffy snow so it is a waste to use it in those situations.
- For traction on icy patches, use sand or cat litter instead of ice melt or salt.
- If you must use ice melt products, apply sparingly and use a pet-friendly version (most people apply more than needed and too much can actually harm the concrete).
- Dilute any ice melt with hot water and use a spray bottle to spray it onto the surfaces you’re trying to cover; this way you’ll use less of the product and it will likely be more effective (or use a liquid version of the melt)
How to Protect Your Plants and Trees From Winter Salt Damage
You can protect some plants by wrapping them in burlap or by putting up a plastic or burlap fence between your plants and the roadway or sidewalk. Keep snow and ice that has been treated by ice melt away from plants by shoveling or pushing the snow elsewhere.
When the snow begins to melt, you may want to try to “flush” out the soil with excess water, especially if there hasn’t been a lot of rain to naturally wash it away. Place a garden hose near the affected area and run it on low for a few hours to help remove salt residue from the soil.
Pines are especially sensitive to the spray from road salt, so be sure to protect them – if you’re planning on planting some pine trees, try to choose a location away from the spray of road salt.
Choose salt-tolerant plants for areas near roads, sidewalks, and driveways. You can see a list of the salt-tolerant plants for Virginia here >>
For more information on how to protect your trees during winter, check out our winter tree care tips for northern Virginia.
But, overall, the bottom line is to stay away from the salt whenever possible and to limit its use. A little goes a long way.