Ice-Melt Products in Your Landscape
Allen Robinson: Ask a
Master Gardener
Sunday, November 25,
2018
Q: It appears we may
have a cold AND wet winter, so I am planning by buying something that will melt
ice on my sidewalks. Will ice-melt products harm my plants and lawn? Randy W.,
Broken Arrow
A: Products used to melt
ice on walks and driveways may harm plants, but this depends on what and how
much is used. Most of the chemicals marketed today to melt ice are just salts
that lower the freezing point of water. All are useful if the labeled
directions are followed carefully.
Four of the most
commonly used chemicals are sodium chloride (table salt), calcium chloride,
calcium magnesium acetate and urea. All are types of salts, except urea, which
is a chemical normally found in fertilizers.
These products thaw
ice but also have some undesirable effects. They may cause corrosion of
concrete and metal and water pollution, as well as harm to plants.
Sodium chloride is the
cheapest and most widely used for ice melt. But it has a significant potential
for corrosion and plant damage in high concentrations. Calcium chloride and
urea have similar risk for corrosion but are less harmful to plants. Calcium
magnesium acetate does not corrode or pollute water and does not harm plants.
However, as you may have already guessed, it also is the most expensive.
Damage to plants
occurs in two ways — first, when directly splashed on plants; secondarily, when
absorbed into the soil. When slush-containing salt comes in contact with a
plant, it may cause direct injury to evergreen leaves and buds, as well as
stems of deciduous plants. This injury, especially in deciduous plants, could
go unsuspected as the damage may not appear until next spring.
Salts that filter into
the soil can kill plant roots by dehydrating them. It can also raise the soil
pH to undesirable levels, thus affecting the overall health of the plant and
its ability to take up proper nutrients. This is the same as fertilizer “burn”
that gardeners are familiar with when too much fertilizer is put (or spilled)
in one location. In addition, large amounts of sodium from sodium chloride can
damage the soil structure, making it less friendly to plants.
So what do you do? The
ideal approach to ice and snow is to remove as much as possible by hand. Not
exactly what you wanted to hear, right? Then, if you feel it is needed, apply
an ice-melt chemical to help remove the last layer. Avoid the “more is better”
mindset and always follow label directions. Mixing sand in a 3-to-1 ratio with
ice melt can reduce the need for chemicals and provides added traction to feet
and tires.
Harmful effects of
these chemicals may be minimized by hosing salt off plants, when it is
possible. Much of the salt in soils may be removed if irrigated with generous
amounts of water. We are fortunate that ice and snows are not long-term winter
problems in our area and that most people are able to cope without ice melt
chemicals.
Garden tips
• Continue to plant
balled and burlapped trees.
• Wrap young,
thin-barked trees with a commercial protective material to prevent winter sun-scald.
• Fertilize
cool-season grasses like fescue with one pound of nitrogen per 1,000 square
feet. This should be the last fertilization for fescue until next spring. Do
not fertilize Bermuda or Zoysia until green-up next April.
• Spring-flowering
bulbs like hyacinth, narcissus and tulip, which are sold for “forcing,” can be
potted indoors for a colorful winter display.
• Tulips can still be
planted outdoors through this month.
• Autumn leaves have
good uses other than placing them in the trash. They may be mowed directly into
the lawn, which will add nutrients and organic matter; they may be shredded
with a lawnmower and added to the compost pile; they may be used as mulch or
tilled into the soil of your garden beds.
• Remove all debris
from the vegetable and flower garden to prevent overwintering of various garden
pests.
• Till plenty of
organic material into the soil in preparation for spring planting.
