Winter can be hard on gardens and landscaping around homes and businesses. When there’s too little snow to properly insulate plants, cold temperatures can be damaging. When there’s too much snow, the weight of it breaking limbs and branches is a concern. Aside from the damage the weather can cause, gardeners should beware of damage caused by deicers — most commonly sodium chloride or rock salt.
Learn what type of damage to look for and how to minimize damage to plants caused by rock salt used as a deicer.
Types of damage
There are two types of damage caused by applying rock salt to sidewalks and roadways during the winter — salt spray and soil-borne salt.
Salt spray. Salt spray occurs when fast-moving traffic or weather distributes or spray salt away from where it was originally deposited. Salt spray damages the leaves of conifers and buds of deciduous trees by pulling the water out of them. It’s especially damaging in late winter and early spring when leaf buds are beginning to appear and swell. Trees and shrubs that have been damaged as a result of salt spray will have leaves and flowers on the side facing the road that do not open or are stunted due to drying.
Soil-borne salt damage. Soil-borne salt damage occurs when salt from a road or walkway accumulates in the soil, either because its been deposited there or from salty runoff as snow and ice melt. The amount of accumulation is dependent on the type of soil and its drainage. Denser, clay-based soils hold more salt than sandy soils. Damage caused by soil-borne salt injury develops slowly over time. An overabundance of salt in the soil can prevent roots from absorbing water and even pull water from affected plants, creating drought-like conditions. In higher concentrations, too much sodium in the soil can compromise the absorption of essential nutrients such as calcium, magnesium and potassium. As plants become weaker from salt damage they are more susceptible to diseases. Although diagnosing soil-borne salt damage can be difficult because symptoms mirror those of other problems, signs include browning edges of leaves, wilting, stunted growth, small yellow leaves and early fall coloration and leaf drop.
How to minimize salt damage
Try these tips from Penn State Extension to minimize salt damage in your landscape:
- Consider using anti-skid products, like sand or cat litter, instead of salt.
- Instead of salt use, deicers that are less harmful to vegetation, such as calcium chloride, potassium chloride and magnesium chloride deicers.
- Move plants away from areas where salt spray or salty runoff accumulates.
- Use plants that are salt-tolerant and avoid salt-sensitive species in your landscape.
- When plants have been damaged by soil-borne salt, apply gypsum (calcium sulfate) in the spring to replace the accumulated sodium ions from salt in the soil. Gypsum will not change the pH of the soil and it has the added benefit of improving the texture of clay soils. Apply at a rate of 40 lbs. per 1000 sq. ft.
- Add organic matter to salt saturated soil to minimize damage.
- Avoid using inorganic fertilizers on salt-saturated soil.
- Drench soil to remove excess salt. Six inches of water will leach out 50% of the salt.
What to plant
These plants are more sensitive than others to an overabundance of salt in the soil:
- Eastern Hemlock
- Red pines
- White pines
- Douglas firs
Try these salt-tolerant plants instead:
- Mugo pines
- Norway maples
- Black locusts
- Green ash trees
- Blanket flower
- Cranesbill geranium
- Coral bells
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