Can Rock Salt Harm your Trees?

It’s Winter; Of course this means snow, ice and slippery roads and lot’s of plowing and shoveling to fill your days. Clearing all that snow and ice is necessary to make our roadways, walkways and sidewalks safer. There are a variety of ways people can deal with all this – deicing agents, rock salt and sand can help to melt the ice or provide drivers and walkers with better traction.

Each of these materials can help improve safety conditions, but each also brings with it environmental problems.

Using a lot of rock salt can be hazardous to nearby plants, aquatic life and animals. Nationwide, more than 22 million tons of road salt is being used during the winter, and it doesn’t just disappear after the snow melts. Evidence is growing that the salt concentration of streams, lakes and even groundwater is increasing. Just think of all the parking lots and roadways where salt is used to melt the ice. The melted water and salt mixture runs off the pavement into drainage systems that end up in streams and lakes. Rock salt is also very corrosive and over time it damages asphalt and concrete. Rock salt can also be damaging to trees. Salt causes a “burn” to the roots and foliage it comes in contact with. Injury is most pronounced on the side of the plant facing the salt source and, particularly on evergreens, on lower branches that can get “salt spray” from passing traffic.

If the area must be salted to prevent accidents and injury, use calcium chloride. It is an effective deicing agent which is much less toxic to plants and can be substituted for sodium chloride on pavements around ornamentals. Other materials including sand and urea are valid, but less effective, substitutes for sodium chloride. Diverting runoff from salted pavements away from existing plantings is a great way to prevent salt injury. Similarly, protective barriers of burlap, polyethylene, wood, etc. will help prevent salt spray from coming into contact with foliage and branches.

Obviously it’s not safe to go salt or deicer free but try not to overdo it either; putting down too much salt or other deicer doesn’t mean it will work faster or better or keep the area clear for a longer period of time. Put the deicer just where and when it’s needed.

If you have any questions, you can contact me at, a Certified Arborist or your County Extension Agent.

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One Response to Can Rock Salt Harm your Trees?

  1. Pingback: Winter Dog Grooming Tips | THE PERFECT GARDEN HOSE

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