I spend a fair amount of time helping people sort through the many garden myths. Today's social media rage spreads information very quickly. Unfortunately it isn't always good information. For example, recipes for homemade weed killers abound on the Internet. University of Illinois Extension Specialist Michelle Wiesbrook explains why homemade is not always better.
Popular homemade weed killers seem to include one or more of these main ingredients: vinegar, boiling water, bleach, baking soda, alcohol, salt, dish soap, and borax. Add a recipe, an adjective like AMAZING or BEST, and a pretty picture to draw attention to it and it seems believable.
Unfortunately, the disadvantages of these home remedies often outweigh the advantages. These products don't contain labels with safety or rate information and yet they can still be hazardous to your health. Vinegar can be effective for weed control but only if it is a strong enough grade, which the bottle in your kitchen likely isn't. Vinegar contains acetic acid and 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 like a "natural" weed-control method, it is important to remember that 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. The borax box tells you how to wash your clothes.
One other important disadvantage 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. Plus, how safe is it to carry big pans of boiling water out the door to your garden?
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. Depending on the area, that may not be too bad you think. A problem with using borax is that the boron it contains does not break down or dissipate like conventional weed killers do so 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.
To learn more about garden and plant myths, join Kari Houle, Extension Educator Horticulture, as she explains why they are myths and gives recommendations for better plant care. She is available via live webinar on Tuesday May 12 at 1:30 pm and again on Thursday, May 14 at 6:30 pm. Or you can listen to a taped version beginning the following week. For more information visit our website at http://web.extension.illinois.edu/fmpt or call 309-543-3308309-543-3308.