Garden areas that border roads, sidewalks and pathways can absorb products that are used to treat those surfaces in snowy or icy weather. Products used to prevent ice include rock salt and mixtures called ice-melt. Rock salt and ice-melt products are chloride based. Here's what to know about their effects on gardens, plus tips for plant-safe snow removal.
If rock salt (sodium chloride) drains or drifts into the soil alongside the paths, it can harm plants and rob the soil of nutrients. Ice-melt products that are made of potassium chloride, magnesium chloride or calcium chloride are slightly less harmful to plants and soil. They are less corrosive and they contain nutrients that plants can use (although they should not be thought of as fertilizer, and fertilizers should never be used to attempt to treat ice).
"Pet-safe" ice-melt products typically do not contain chlorides, but instead rely on urea to work. These products aren't corrosive, but urea has a high nitrogen content; this may cause problems in the garden and can do harm in waterways when the product is carried there by runoff.
Related: "Protect Trees and Shrubs in Winter"
If you need to use ice-melt to help prevent slipping on a pathway or steps that abut the garden, read the packaging closely and carefully follow the directions. Applying the product appropriately should minimize damage. Here are some general guidelines for applying ice-melt products:
- Apply the product before the snow and ice begin (as long as you know they're coming), or just as it starts to snow or sleet. Apply only a small amount.
- Use the least amount possible to get the job done. Start with a small amount, let it completely dissolve and go to work, then apply more if needed. If you can see lots of ice-melt granules on the paving after the snow and ice is gone, know that you used too much and adjust your approach for the next storm.
- Keep in mind that ice melt may not work well when temperatures are extremely cold. Some products, including rock salt, do not work below 15˚F. Others may work, but less effectively than at higher temps. Keep this in mind if the product seems to not be working—don't jump to applying more, but instead wait for the temperature to warm up some.
Here are some other tips for keeping walkways ice-free and plants safe in winter:
- Don't put ice-melt products on top of snow. Shovel or blow the snow away, then apply ice melt to the bare pavement to prevent any additional precipitation or drifting from icing up.
- Removing ice without a melting product is of course safest for plants. Thin layers of ice can sometimes be chipped or scraped away, particularly if the sun is working on them too.
- Consider using sand to provide traction on mildly slippery surfaces or seldom-used paths instead of applying ice-melt.
- Shovel or blow the snow as soon as possible after a storm, so ice has less chance to form. Work in a way that lets you avoid stepping on the snow before you remove it. Ice often forms where people have compacted the snow against the pavement by stomping on it.
- Try to avoid shoveling or blowing snow directly on top of plants and shrubs, especially if the path or driveway was pre-treated with and ice-melt product, which would be carried into the garden with the snow you're moving. Move snow, slush and ice away from your most treasured plants.
- Salt spray can also be a problem, especially for evergreens planted near roadways, where plows kick up the products. Burlap can help protect plants in these areas, but the best option may be to choose salt-tolerant species (such as those recommended for coastal gardens) in such spots.
