Almost everyone is familiar with Sodium Chloride, but you are probably more familiar with its common name, salt. This flavor enhancing mineral is a common additive to food – but consuming too much Sodium Chloride will compromise your health. Harm from excessive salt isn’t exclusive to people though; it also causes significant damage to trees and shrubs.
The impact of salt on plants has been known for many years. Our ancestors were aware of this and used salt for biological warfare, utilizing it to destroy their enemy’s fields and crops. As we move further into winter and snow becomes an increasing possibility, careful salting of driveways and walkways is necessary for preventing salt damage to your trees and shrubs. Sodium Chloride may be a common and cheap fix for icy surfaces, but if applied in excess or in close proximity to your plant material, it can cause considerable damage.
The Root of the Problem
Once salt is applied, it gets into the melting snow and saturates the soil around adjacent plant material. When salt gets into the soil in excessive quantities, it has a number of adverse effects on plant life. Roots have a hard time taking up water that is overly saturated with Sodium Chloride. As salinity increases in the soil around a plant, salt will actually draw water out of the root system, causing the plant to divert energy that would have been used to promote growth and survival, and instead use it to absorb water. Additionally, after roadways have been salted, passing vehicles can create a spray of salty-slush that coats nearby plants, drawing the moisture out of leaves, twigs, and buds and leading to deformity and slowed growth.
Since many trees are already taking in less water during the winter, the side effects become most apparent in the spring. Signs that salt has exceeded a healthy level include stunted growth, yellowing leaves, and slow penetration of water into the soil. In affected conifers, needles will turn brown and drop. If spring rains are heavy and consistent, damage will be lessened as the soil is flushed and salt levels reduced. In cases where spring rains are not adequate, it will be necessary to increase irrigation around the affected plant material in order to lower the concentration of salt around the root system.
Solutions and Alternatives
The best thing to do is to be mindful of what you are using to clear snow from your drive and walkways. Consider using alternatives like Calcium Chloride, Magnesium Chloride, or Potassium Chloride, which are less damaging to plant material when properly applied. Additionally, pre-treating surfaces prior to rain or snow requires substantially less product to be applied which is better for surrounding plant material. If you have trees or shrubs next to a roadway, consider covering them with burlap as a preventative measure against road salt applications that are out of your control. And finally, if you are unsure about the health of your trees and shrubs, or you would like an analysis of your soil, a Consulting Arborist can help!