Will Magnesium Chloride Harm My Lawn Or Garden?

WINTER! It's the time of year when you spend the least amount of time thinking about your lawn. But did you realize that your lawn is especially vulnerable to damage in these cold months?

One of the main culprits are de-icers such as rock salt – also known as road salt or sodium chloride (NaCl) – which was first used as a de-icer in the 1940's. Rock salt is an effective, abundant, and relatively cheap de-icer and is by far the most common de-icing chemical in the United States. In fact, our roads across the county see around 10 million tons of salt per year, not to mention the added tons of salt and other de-icers we apply to our driveways and sidewalks.

While salt de-icers serve a good purpose, excessive salt deposits can translocate to the stems, buds, and roots of trees, shrubs, and landscape plants which causes disfigured foliage, stunted growth and severe decline in health. Salt runoff washes from pavement into the ground, and increases salt levels in the soil, often burning grass.

Other de-icers such as calcium chloride and magnesium chloride can also cause a great deal of damage to your lawn. The Consumer Reports Ice-Melt Comparison below should give you an idea of the pros and cons of the most commonly used de-icers.

Consumer Reports Online, Ice Melt Comparison: Consumer Reports Online, Ice Melt Comparison (CLICK HERE)

Homeowners often do not make the connection about what causes the "mysterious" damage symptoms they see in their lawn come spring.

So how can you avoid winter lawn damage?

Here are 5 simple tips you can follow:

1. Apply Salt Sparingly – The recommended application rate for sodium chloride or rock salt is one handful per square yard treated. The rate for Calcium chloride is even less salt-one handful for every three square yards treated (an area about the size of a twin bed). You might think that using more salt than this will speed up the melting process, but that is not true. Sand, light gravel, cinders and cat litter won't melt ice completely, but can provide some traction and can be used in conjunction with de-icers if you're looking to use fewer chemicals.

2. Read Labels for Spread Rates – Check the label before you buy. For instance, calcium chloride (CaCl2) is slightly more expensive than sodium chloride, but it requires less product, works at lower temperatures and does not contain cyanide, unlike sodium chloride (NaCl, rock salt) which does.

3. Avoid Using de-icers that Contain Urea – Urea has is also used as a lawn fertilizer due to its very high nitrogen content. De-icers with urea are marketed for their dual deicing/fertilizing properties. The idea is that not only will it de-ice your driveway, but when it washes away, urea's fertilizer properties will boost your lawn growth. Sounds like a good buy, right? Well, not exactly. Urea is actually a more costly method of deicing, compared to others. It performs poorly under temperatures of 25°F, and can burn the lawn edges if it lies concentrated for any length of time. If you are drawn to urea because of its dual deicing/fertilizing purpose, keep in mind that in the spring when the rain and melts come, the soil in your lawn will still be frozen for some time before thawing. It is likely that the urea will still run off of your lawn and into a storm drain or local waterway. Excess urea in our lakes, rivers, and streams is not a good thing because the nitrogen in the urea can cause a chemical imbalance and endanger the water source's ecosystem.

4. Shovel Early and Often – The best method to keep your pavement clear is to remove fresh snow before it has a chance to harden into ice. de-icers work best when there is only a thin layer of snow or ice that needs to be melted, so shovel first, break up any ice patches you can, and then add the salt.

5. Minimize Traffic Across Turf – While not specifically de-icer related, this tip is important because your grass becomes very brittle and cell walls actually crack when they the blades are frozen and then stepped on. While your lawn will usually grow out of this kind of damage in the spring, constant traffic can do irreparable harm. Avoid activities like creating huge heavy piles of snow while shoveling, walking across your lawn to go check the mail, or sleigh riding on a fine lawn, even in deep snow. Pet traffic should also be minimized if possible. All of these types of activities can cause brown areas to appear in early spring.

LEARN MORE:
Salt Damage in Landscape Plants via Purdue Extension