Protect plants from salt spray
If you live on a busy street where winter road crews often use salt to keep the asphalt free from slippery snow and ice, you’re probably all too familiar with the havoc road salt can inflict on trees, shrubs and other plantings.
Road salt can be damaging to plants in two different ways. First, when the salt dissolves and mixes with the melted snow and ice, passing cars easily drench nearby plantings with this salty splash. For both needled and broad-leaved evergreens, this can cause salt burn on their foliage. Salt burn of this type often appears across entire portions of the plant.
It isn’t problematic if the salt is quickly washed off of the plant via rain, but if the saltwater sits on the plant for prolonged periods of time or on a frequent basis, it can lead to complete foliage browning and even leaf-drop. In severe cases, it can also lead to plant death.
Another, more significant, way road salt can negatively affect nearby plantings is by salinizing the soil. Both the salt itself and the briny solution created when the salt dissolves in water can cause a dramatic salt build-up in the soil. High amounts of salt in soil can damage tender root tips and inhibit water uptake, causing “salt burn” by actually drawing water out of root cells. Salt in soils can also increase soil compaction.
While asking passing cars not to splash your plantings is an impossible task, protecting your plants from salt damage is not.
There are several things you can do to limit the damage caused by road salt this winter.
The first and easiest method is to physically block the salt splash from coming in contact with plantings. Build a simple barrier of landscape fabric stapled to 4-foot tall, 1-inch-by-1-inch hardwood stakes in between the road and your plantings.
This fabric fence will stop most of the spray from landing on your shrubs and other plants. Make sure the barrier is erected in such a way that it’s angled to withstand the force of the incoming salt spray.
You can also surround individual plants with a barrier fence like the one described above, rather than surrounding an entire planting bed. This is helpful if you have just one or two evergreen plants in an area with deciduous trees and shrubs that do not need to be protected from salt spray to the same extent.
The second option is a bit more time-consuming but equally as effective. This method involves regularly rinsing off your evergreen plants with fresh water soon after salt is used on the roadway. This washes the saltwater off of the foliage. It’s a task that can prove challenging during the winter, when hoses are often frozen solid. But, again, it’s a useful method if you just need to protect one or two plants.
A third option is to replace any salt-sensitive plants with species that are salt tolerant. Thankfully, there are plenty of plants that have evolved to tolerate both salt spray on their foliage and salty soils (think beach plants!). Junipers (Juniperus horizontalis and J. virginiana, in particular), bayberry (Myrica pensylvanica), winterberry (Ilex verticillata), Japanese cedar (Cryptomeria japonica), Amerian holly (Ilex opaca), sweetbay magnolia (Magnolia virginiana), and Cotoneaster (Cotoneaster divaricatus) are a few excellent options.
As for remediating soil that’s been regularly drenched with road salt, dilution is key. Over time, water will flush the salts out of the soil, so make sure your street- and curb-side plantings receive ample water in the spring to aid the process. If we don’t have adequate rainfall, the Virginia Cooperative Extension suggests flushing the soil with 2 inches of water applied via an overhead sprinkler over a two-to-three-hour time period and then repeating this treatment three days later. Adding regular additions of high-quality compost to the area can also help the salts process through the soil.
Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio with Doug Oster. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden,” “Good Bug, Bad Bug,” and her newest title, “Container Gardening Complete.” Her website is jessicawalliser.com. Send your gardening or landscaping questions to firstname.lastname@example.org or The Good Earth, 622 Cabin Hill Drive, Greensburg, PA 15601.