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Weekly Gardening Tips: Salt alternatives for the homeowner

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By Bob Beyfuss

For Capital Region Independent Media

Headshot of a man named Bob Beyfuss.

The pre-Christmas snowstorm, followed by a rainy meltdown, gipped many of you from experiencing a white Christmas this year, but if you had to travel, it was probably a relief! But right after Christmas, a deep freeze made travel even more dangerous once more.

Any surfaces that appear wet are probably covered with black ice. Our local highway departments have been busy spreading salt for weeks now. Rock salt prices in New York have increased on average, 43% since 2015, from $44.55 per ton to $63.90 per ton, according to the county highway superintendents’ association. Towns like Greenville use about 1,000 tons of rock salt per year.    

Rock salt takes a heavy toll on road structure. It reacts chemically with both concrete and asphalt, creating cracks. Potholes begin when water gets into tiny cracks in the road. As that water freezes, the freezing process creates forces that can easily break asphalt or even concrete. Soon, the cracks grow into bigger and bigger potholes with every freeze and thaw.

Of course, down here in Florida we have fewer potholes, but we do have some serious issues with sinkholes that sometimes swallow houses or cars, overnight. Most of the parking lot near a strip mall that I like to shop at disappeared about three years ago and it has just now finally reopened! 

It is not uncommon in the Capital District and Hudson Valley for heavily traveled roads, such as the Thruway, to receive 40 to 80 tons of deicing salt per lane mile per year. That works out to about 15 to 30 pounds per linear foot. It is surprising that any roadside plants can tolerate that much salt, but most do. If they received a fraction of this much salt during the growing season, the roadsides would be devoid of vegetation.

There is little the homeowner can do to change the road salt situation, but there are some alternatives to rock salt that may be used in the home environment.    

Road salt, or deicing salt, is mostly unrefined rock salt, containing about 98.5% sodium chloride. Calcium chloride is sometimes used when temperatures are extremely low (rock salt is useless at temperatures below +10 F.) but it is about eight times as expensive as sodium chloride.

Rock salt causes injury to plants by absorbing water that would normally be available to the roots. Even when moisture is plentiful, excess salt can create a drought-like environment. In addition, when salt is dissolved in water it breaks down into sodium and chloride ions. 

Roots readily absorb chloride ions and then they are carried through the sap stream to actively growing portions of the plant such as leaf margins and shoot tips. High levels of chloride are toxic and result in characteristic marginal scorch patterns (brown edges around the leaves).

Calcium chloride is not nearly as damaging. Calcium chloride can melt snow and ice in cold weather conditions as low as -25ºF. Calcium chloride is fast-acting; within 20 minutes of application at about 20ºF, it will successfully melt twice as much ice or snow as traditional rock salt. Calcium chloride ice melt leaves less residue, making it a better choice for use around buildings, like commercial properties and municipal buildings. It also leaves less white or gray residue when tracked indoors.

Plants most likely to be affected by any salt in the home landscape are those that receive lots of salt-laden snow. For example, if you routinely apply salt to your porch or steps or deck, the plants growing nearby are most at risk, especially if you continually shovel salty snow on top of their root systems. 

Likewise, plants along your driveway or roadside are more at risk than those in the backyard. Certain species of trees and shrubs are more sensitive than others to salt injury. Sugar maples are highly sensitive to salt damage, which is why they should never be used as roadside trees or even driveway trees. Norway maples are far more salt resistant.

So what are the alternatives? If you just want to improve traction, you can try using sand or kitty litter or even fine gravel. Keep in mind however that you will most likely be tracking these materials into the house along with the snow on your boots. Never use soiled kitty litter for this reason!

Wood ashes have also been used for traction, but too much wood ash spread over your plants can raise the soil pH to damaging levels. Wood ash will also be carried in the house with the snow on your boots and it leaves an unsightly gray residue.

aCalcium chloride is, by far, your best choice for home use. It is well worth the extra cost!

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