Coles County Yard and Garden

Coles County Yard and Garden

Homemade weed-killers May do more harm than good

By Marsha Overton, Master Gardener



If you spend much time on social media during the growing season, you'll likely see posts about supposedly "AMAZING" weed-killers than can be made from common household ingredients.

But in a recent article, U of I Extension weed scientist Michelle Wiesbrook explained why homemade is not always better – and may, in fact, be downright hazardous to people and the environment!

Popular mixes typically include one or more of these main ingredients: vinegar, boiling water, bleach, baking soda, alcohol, salt, dish soap and borax. There is a certain comfort level associated with these products. They can be found around the home, after all. Some are even edible.

Unfortunately, the downsides of these home remedies often outweigh the advantages. These combinations don't carry labels with safety or rate information. Certain concentrations or mixes of household ingredients may still be toxic or have unwanted side effects.

Vinegar can be effective for weed control but only if it has a high enough concentration of acetic acid, which the bottle in your kitchen likely doesn't. But acetic acid concentrations over 11% can cause burns upon skin contact. In fact, eye contact can result in severe burns and permanent corneal injury. This is why reading and following the label is so important. There are now registered herbicidal vinegar products you can buy that have use-and-safety information on their label.

Although borax may sound "natural," it may still be harmful to children and pets. Mixtures should be kept out of their reach. Registered pesticides have been studied extensively and come with labels that tell you how to protect yourself and others.

Another problem is that the boron it contains does not break down or dissipate like conventional weed killers do; repeated or excessive applications can result in bare areas where no vegetation can grow. Similarly, salt can be used for long-term weed control. But it destroys the soil structure and it is mobile, meaning it can move to nearby areas in your garden resulting in unwanted plant damage

One other important disadvantage of homemade "herbicides" is that weed control often is only temporary or partial with only the top growth being affected. Boiling water would certainly be death on green leaves. The roots, however are protected. If your weed is a perennial or if it has a deep taproot, you can bet it will grow back.

Some homemade weed-killer ingredients can have a lasting effect on the soil making it so that nothing will grow there for a long time. Conventional herbicides are made to break down or dissipate in a timely fashion. Unfortunately, the result is new weed growth but at least the soil is healthy and can promote growth.

While some claim their recipes or methods are more effective or longer-lasting than registered herbicides, what about their environmental impact? Are these products mobile in the soil? Will they end up in the groundwater? Have they been tested for this use? Would EPA approve of these weed-control methods or would they instead insist that the contaminated soil must be removed? We need to think about these things!

If you have other questions about your garden or landscape, feel free to contact a Master Gardener volunteer at the University of Illinois Extension office in Charleston at 217-345-7034. You can also check out the many horticulture webpages at the U of I Extension's website by visiting http://web.extension.illinois.edu/ccdms/ . And be sure to like the Master Gardeners' Facebook page, at www.facebook.com/ColesCountyMasterGardeners.

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