Ice, Snow, and Salt

This article was originally published on November 1, 2008 and expired on February 15, 2009. It is provided here for archival purposes and may contain dated information.

Advance preparation can minimize the potential damage to your home landscape from winter storms, said a University of Illinois horticulture educator.

"Every winter, Illinois can expect several ice and heavy snowstorms," said Jeff Rugg. "These can do a great deal of damage if the ice forms from one-half to a couple of inches thick. Even a thin glaze of ice can snap small twigs. And ice storms do more damage when they are followed by snow or wind."

Getting ready involves taking pre-emptive measures with your landscape.

"Check multi-stemmed plants and evergreens to see if they need to be supported or tied together," he said. "Branches that come off the vertical trunk and stay almost vertical are at the most risk. Branches angled almost horizontally are at the least risk.

"Any branch or trunk that has disease problems and is beginning to rot is at a greater risk of breaking."

A properly pruned tree is less likely to be damaged. Rugg recommended pruning as many vertical and weak branches from the tree as possible. Use props of strong boards under large horizontal branches before an ice storm is due to hit. Guy wires can be used to support the tree and can also be used between trunks on multiple-trunked trees.

"Don't worry about annuals, perennials, or vines but don't walk on grass or ground-cover plants that are coated in ice as you can damage the crown of the plant," he said.

Once the winter storm hits, be careful when trying to move bent-over branches. Ice can snap the branches off if you try to get the ice off.

"Cold branches are already brittle, but the ice makes it worse," Rugg said. "Gently brush off heavy, wet snow as soon as possible to prevent limb breakage. Be especially careful if the snow is sticking because of freezing rain underneath.

"A broom will work better than a shovel which could damage the bark. Use the broom to gently brush the snow upwards on bent-over branches. Pushing the snow down may snap off the branch."

A bright, sunny day can shine through the ice onto the tree bark, causing it to warm up and melt the ice off the tree. If a thaw or sunny day is not predicted in the near future, it is possible to melt the ice off with more water.

"A garden hose can be used to gently apply warm water onto the limbs that are most bent over and the ice will melt off," he said. "Don't use a mist of water as that will add to the ice layer."

Broad-leaved evergreens like boxwoods or hollies and needle-leaved evergreens like arborvitae or yews will often bend almost flat to the ground with heavy snow loads.

"In many cases, they will recover when the snow melts," he said. "If they don't come back by spring, they may need a pruning program that creates sturdier stems capable of holding more snow."

Every winter many people do a lot of damage to their landscapes by the misuse of salt that is applied for snow removal or the use of liquid ice melters. A variety of products are available and they all help keep the last little bit of ice and snow off the walks and drives, but none are supposed to be used instead of shoveling, he noted.

"There are some liquid ice melters that use ethylene glycol, which is used in antifreeze for your car. Do not use it around plants or if you have pets," Rugg warned. "Dogs find the sweet taste a treat, but ethylene glycol is poisonous. It is applied with a sprayer, but the mist can be harmful to humans as well."

Unlike the local streets, you can apply smaller amounts of salt to your drive or walks. You can mix in sand or use just sand to make the areas safer too.

Apply any ice-melting products at the beginning of the snow or ice storm.

"This concentrates the product on the surface which prevents the ice from bonding to the surface," he explained. "This means less is needed and it is more effective. The salt is more effective because the surface is warmer when it is applied and the chemical doesn't have to melt its way down to the surface though a thick layer of snow.

"Salt will damage the roots of plants. When high concentrations are pulled into the plant, the new leaves and shoots can get brown edges of dead tissue as the salt accumulates in them."

Soil with high salt levels can be flushed with water to help reduce the concentration of salt.

"Don't keep adding salt to icy or snow-covered pavement areas to avoid shoveling," said Rugg. "The extra salt will eventually wash into the rivers as a pollutant."

Salt can also take a mist form when used on roads. This mist can blow for more than a mile, damaging evergreen leaves as the mist accumulates on them.

The cheap salts used for most ice-melting products are calcium chloride or sodium chloride, both of which can kill plants quickly.

While some gardeners think that fertilizers can be used for ice melting, Rugg warned that it can also be harmful and some portions of it will wash into the storm sewers, fertilizing streams, and creating algae blooms and other problems.

"The good that salts do in protecting drivers is counteracted by the harm they cause to roadside vegetation, cars, roads, bridges, wetlands, and rivers," said Rugg. "There are many companies working on an ice-melting product that will not harm plants, roads, and bridges. Some of these are based on renewable corn products.

"One such product is Ice Ban (http://www.iceban.com), a natural liquid concentrate residue from the wet milling of corn and the production of alcohol. Not only does it not harm vegetation, it delivers valuable nutrients to the soil and may enhance vegetation growth."

It is also less corrosive on metal than other anti-icing chemicals, he added.

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Source: Jeff Rugg, Unit Educator, Horticulture/IPM, jrugg@illinois.edu