Chicago Botanic Garden

YOUR GARDEN — Plant Information

Pests, Problems, and Diseases

Salt and Snow Injury to Shrubs and Trees

 

Susceptible Plants
All plants, especially those sited on parkways or near heavily salted and frequently shoveled areas. Evergreens are particularly vulnerable.

Description & Symptoms
Salt injures plants in two ways. It soaks into the soil with melting snow and is taken up by plant roots. It also becomes airborne, especially during dry winters, and is blown onto the leaves or needles of evergreen plants.

Ice and snow weigh down tree and shrub branches, causing breakage. This can be a serious problem with evergreens that have double trunks and split open under the weight of snow. Arborvitae often is damaged in this way.

Timing & Life Cycle
This is an ongoing issue throughout the winter. It is especially urgent during heavy snow or ice storms.

Damage
Salt draws moisture from plant cells, causing tissue to dry out. This happens whether the salt is taken into a plant through its roots or is absorbed through the surface of the leaves. Airborne salt often is more damaging than soil salt, which eventually leaches from the soil with melting snow and spring rains. Needled and broadleaved evergreens are more susceptible to salt damage because they are not completely dormant in the winter and because they still have leaves that receive salt spray. Salt damage in deciduous plants may produce scorched leaf tips and margins in the spring.

Treatment & Controls
Always use the minimum amount of de-icer necessary. A calcium- or potassium-based de-icer is somewhat less damaging to plants than sodium chloride (salt). Shovel snow first, and never use a de-icer as a substitute for shoveling. Avoid shoveling salt-laden snow on to plants and distribute shoveled snow as evenly as possible.

After a snowstorm, gently remove snow from branches that are bending to the ground, being careful not to damage branches. Do not try to crack ice off branches after an ice storm. Wait for ice to melt. Many evergreens that are bent over by winter snow recover their natural upright shape in the spring.

When planting evergreens, keep in mind that plants sited near parkways, entrances, and driveways may be heavily exposed to salt in the winter. Valuable evergreens can be somewhat shielded from salt spray with burlap barriers, although they should not be wrapped tightly.

 

For more information aboutwinter injury to plants, call the Plant Information hotline at (847) 835-0972.