Almost everyone is familiar with Sodium Chloride, but you probably just refer to it as salt. The flavor enhancing mineral is a common additive to food- but too much Sodium Chloride and you’ll find yourself compromising your health! Damage from excessive salt isn’t just exclusive to people; it harms your plants too! This unfortunate truth has been accepted for many years, as even the ancients used salt for biological warfare, using it to destroy their enemy’s fields and crops. Knowing this, as we move further into winter and snow becomes an increasing possibility, mindful salting of driveways and walkways is necessary for preventing plant damage. Sodium Chloride may be the most commonly used and the least expensive, but it is also the most harmful to plants.
Once salt is applied, it gets into the melting snow and saturates the soil around a plant. When salt gets into the soil in excessive quantities, it has a number of adverse effects to plant life. Roots have a hard time up taking water that is overly saturated with Sodium Chloride. As salinity increases, the salt can even draw water out of the plant’s roots. This causes the plant to divert energy that would have been used to promote growth and survival, and use it to draw up water instead.
After roads have been salted, cars driving by cause a spray of salty-slush that coats nearby plants. This draws the moisture out of leaves, twigs, and buds, deforming plants and slowing growth. Unfortunately, this also reduces the plant’s cold hardiness.
Because many trees are already taking in less water in the winter, the side effects become most apparent in the spring. If spring rains are heavy and consistent, damage will be lessened as the soil is flushed and levels of sodium chloride are reduced—however, if spring rains are not adequate, you may need to take action yourself. Signs that salt in the soil have exceeded the level that a plant can tolerate include stunted growth and yellowing leaves (in conifers, needles will turn brown and drop) as well as increasingly slow penetration of water into soil.
The best thing you can do is be mindful of what you are using to clear snow. Sodium Chloride may be the least expensive, but there are equally effective methods that are less harmful (if used as recommended) to plant life. Calcium Chloride, Calcium Magnesium Acetate, Magnesium Chloride, and Potassium Chloride are all good alternatives. If you have trees that are close to the road, protecting them with burlap is a good preventative measure against road salt applications that are out of your control. If you are unsure about the health of your trees and shrubs, or you want an analysis of your soil, our Consulting Arborists can help!