Berks County Cooperative Extension -

MELT ICE HORTICULTURALLY

Unrefined rock salt.

As our towns are hit with more ice and snow this winter, we will all work very hard to keep our sidewalks and driveways clear and safe. After the snow and ice are shoveled and plowed, most homeowners apply materials to melt the ice beneath. The most common material used to melt ice is unrefined rock salt. Rock salt is about 98.5% sodium chloride. This chemical is the same compound as table salt and is also an ingredient in water softeners.

How salt affects plants.

All plants have different levels of tolerance, but many are very sensitive to salts. Salt toxicity can injure plants and damage soil in the following ways:

Large amounts of salt or sodium can block the nutrients needed by plants.
Salt also absorbs significant quantities of water, causing a drought-like situation.
Intake of high levels of salt can also cause the leaf margins and the tips of new shoots to turn brown. Just splashing a plant with salty water can damage buds, twigs and new leaves.
Sodium also damages the soil structure by compacting it to the point where it inhibits root growth.

Moderate application recommended.

For these reasons mentioned above, it is wise to apply rock salt in moderation if you are applying it near shrubs, groundcover, turf or other plantings. It should be taken into consideration that salt can still cause damage in water runoff. The US Department of the Interior Park Maintenance Division considers the maximum safe application to be 1/2 pound per square yard per season.

Alternatives to rock salt.

Although rock salt is the most effective material for melting ice, there are some other alternatives that will keep plants healthier. Fertilizer is quite beneficial to plants, of course, and does have some chemical compounds with the ability to melt ice. Potash or KCl as well as pure nitrogen also has the ability to melt ice. Pure nitrogen melts ice at temperatures as low as 11ºF. Pure nitrogen should be applied at a rate of ten pounds per 100 square feet. If you have a small area to cover, three pounds of nitrogen and 100 pounds of sand works well in a mix. Be careful: too much fertilizer can harm plants, too, so always apply at the recommended rates.

Combining rock salt with other materials.

The use of rock salt in conjunction with other materials is another option that reduces the amount of rock salt used. Many materials can provide good traction while a lesser amount of rock salt will still melt the ice. Some good traction materials are sand, gravel, cat litter, and cinders. Mixing rock salt with sawdust also helps with traction and absorbs a large portion of the salt water runoff. The wet sawdust can then be disposed of.

Watchful winter eye.

Perhaps this winter will not require much shoveling and ice melting-but just in case, remember to do it carefully and horticulturally. A watchful eye this winter will help insure a beautiful and healthy spring for you and your landscape.

Author: Laura L. McNutt, Extension Agent - Horticulture
Document created: 4 February 2001