On an average 2” snowfall snow removal company’s fleet of salt trucks spread more than 300,000 pounds of rock salt. This does not include the shoveling crews who spread more than 6,000 pounds of calcium chloride over sidewalks and driveways. When you factor in state, county, township, village and all landscape companies salting operations, the Chicago and Milwaukee areas are usually swimming in salt. Though salting is a necessary evil in preventing vehicle and pedestrian accidents, its drying effect on outdoor plants can be devastating.
Salt damage occurs in two forms:
1) The buildup of salt surrounding soil, adjacent to sidewalks, curbs and parking lots.
2) Salt spray from vehicles traveling on roads, parking lots and toll ways.
Salt in the Soil
Salt that is deposited onto the soil leaches into the ground and absorbs any January thaw melt off (in our case March) or early spring rains. Grass and plant roots are prevented from in taking ground water during the crucial time they are breaking winter dormancy and beginning spring growth. There are four ways you can alleviate salt buildup in your property’s soil.
1) In the spring, rake up any visible salt pellets or crystals and then water in areas affected by overspreading. The water in combination with the gypsum application will help leach soluble salts out of the crucial first 12” of soil.
2) Accept the fact that you are going to have both salt damage and turf grass die back along sidewalks and other heavily salted areas. Topdress and re-seed these areas as early as possible in the spring with 50% annual rye and 50% perennial rye seed mix. With an initial watering, you will get almost instant seed germination (one day) and turf grass that will last all season.
3) Ask your contractor to be diligent in applying salt to sidewalks, roads and parking lots. Most salting equipment has deflectors that can help prevent over applying salt on non-target areas. Make sure that your contractor’s equipment is operating properly and that the salt auger and spinners are set at the right calibration for your site. The next time you call for salt, watch your contractor at work and see that everything is operating smoothly.
4) Prior to winter, in mid to late fall, apply gypsum (calcium sulfate) at a rate of 35lbs. per 1,000 sq. ft. to turf and flower bed areas that experience winter salt damage. Gypsum replaces salt in the soil and allows soluble salt to leach below root levels.
Salt spray onto evergreen needles or on the branch tips of deciduous trees can cause both localized and systemic damage to the affected plants. The depositing of salt on live plant tissue draws moisture out of the plant cell membranes towards the salt. Whole branches can die back, but usually a phenomenon called witches broom occurs. Witches broom is a broom-like growth or mass proliferation of buds and shoots at the tip of branches where salt spray has accumulated. The affected plants continue to develop this distorted branch growth, which in turn stunts the overall growth of the tree and destroys the natural growth pattern.
There are four ways to protect plants from salt spray damage.
1) In late winter or early spring, weather permitting, spray down salt affected plants with generous amounts of water. This will help eliminate salt concentrations around new bud and shoot growth, which will significantly reduce the chance of branch die back and witches broom growth.
2) Replace salt damaged plants with shrubs, trees and perennials that are salt tolerant.
3) Apply two mid-December, late February applications of anti-transpirant to tree and shrubs susceptible to salt spray. Anti-transpirant is a wax-like substance that is sprayed onto plants which forms a protective coating that help stop salt from penetrating to live plant tissue.
4) Protect trees and shrubs by putting up burlap or plastic fencing barriers to deflect salt away from plants.
SALT TOLERANT TREES
Honey Locust, Kentucky Coffee Tree, Arborvitae, Hybrid Elms, and Austian Pine
SALT TOLERANT SHRUBS
Bayberry, Cotoneaster, Black Chokeberry, Burning Bush, Sumac, Alpine Currant, and Junipers
Cora Bells, Sedums, Veronica, Dianthis, Coreopsis, Maiden Grass, and Northern Sea Oats
A full Service landscape contractor will be able to provide you with costs and options on how to best protect your landscape from the ravages of winter salting.