With winter once again bringing snow and ice, we are preparing for the task of clearing driveways, roads, and sidewalks. For many, this means the use of de-icing salts to ensure a safety for cars and people. Unfortunately, many of our trees and shrubs are susceptible to injury from salt usage in the landscape.
The most widely available and affordable de-icing agent is sodium chloride, or common salt. This is a very corrosive option, not only damaging the plants in the landscape, but also causing corrosion of vehicles and eventually making its way to our lakes, and raising the salinity of our lake ecosystems. Salt also accumulates in the soil, which raises soil pH, destroys soil structure, and damage healthy soil microbes and mycorrhizal fungi. This all contributes to the soil being inhabitable to tree roots. High enough soil salinity can even lead to drought damage in trees and shrubs. Salt spray hitting plant foliage can also cause damage. Salt on foliage can dehydrate tissues and cause salt “burn”. This interferes with photosynthesis and weakens plants. Plants are often more susceptible to salt injury in the late Winter and early Spring, because the plants are preparing to break dormancy and are starting to take up water and nutrients again.
To avoid or lessen damage from using salt, follow these tips:
- Avoid over-use of salt. Try to use it only in high traffic areas where it’s needed. Use only enough to melt ice. You may need less than you think.
- Clear snow and slush early, before it has a chance to bond to the pavement, and salt after you clear sidewalk and pavement.
- Avoid using broadcast spreaders that may throw salt beyond pavement and into garden beds.
- Avoid using purely NaCl. Try using a combination of 5% salt and grit (sand, kitty litter, cinder, etc). This is especially helpful when temperatures drop really low. Pure salt becomes less effective at lower temperatures under 20 degrees F, and the grit provides enough traction for foot traffic.
- Do not use commercial fertilizers as de-icing salt. This will burn the roots of surrounding plants.
- Plant salt-tolerant species near driveways and sidewalks. Consider planting trees and shrubs on a berm to avoid salt settling into their root zones.
- During warm spells in Winter, or in early Spring, go out and rinse off any plants that get salt spray. Give susceptible plants a deep water to help flush the salt from the soil.
- Avoid plowing snow that has salt over the root zones of trees and shrubs.
If you suspect your trees or shrubs are suffering from injury due to salt, contact us to have a Certified Arborist assess your trees.