My brother was helping tend my garden. Searching the leaf shapes for clues, he asked, “Which ones are the weeds?” I replied with a wink, “The ones you don’t want, of course.”
Merriam-Webster defines a weed more precisely as “a form of vegetable life of exuberant growth and injurious effect.” The definition can be subjective—what one person sees as a weed, another might add to the salad bowl (see “Weed Eaters,” page 82). Yet identification is easy when compared to removal. Anyone who’s battled the tenacious, sunny yellow flower-tops called dandelions knows it. Exuberant, indeed!
You could take the easy, chemical attack, but it’s not the best approach. Common herbicides damage more than weeds; they poison your yard’s balanced ecosystem—and possibly that of your regional watershed—by killing beneficial plant diversity.
The long-term risks of human exposure to weed killers are still unclear, although there’s evidence linking them to some forms of cancer; damage to the kidney, liver, and nervous system; and fetal growth retardation and genital deformities. Do you really want your kids and dog to play on a lawn sprayed with synthetic chemicals? Thankfully, there are eco-friendly alternatives that control weeds and promote a healthy yard.
Prevention is the Best Medicine
Homemade weed killers fall into the category of post-emergence controls, which means they kill the weed after it's broken through the soil and is visible. You've probably heard claims of super-duper solutions using everything from rock salt to gin. While the effectiveness of many is inconsistent, a few have proven results.
• BOILING WATER: It sounds too simple: Boiling water kills weeds. Unfortunately, it also kills the plants you love, so use caution. This is a terrific way to clean up large weed patches. A teakettle is a handy applicator, providing a steady and fairly small stream. While the grass around them might initially die off, eventually the spot will disappear.
• VINEGAR: In 2002, the USDA Agricultural Research Service announced it had proven household vinegar to be an effective weed killer, supporting popular theory. The pickling condiment's high acidity proved particularly lethal to Canada thistle but also worked well on young weeds. For older weeds, a higher concentration of vinegar worked best; it isn't available for public purchase because of its use as an ingredient in commercial-only sprays. Reapplications of fruit- or grain-based vinegar (never use petroleum-based) may increase your success rate.
Take a wait-and-see stance when using store-bought controls—the results aren’t instantaneous like many chemical solutions.
• CORN GLUTEN MEAL: Although it has yet to take off in the marketplace, corn gluten meal is so effective as a pre-emergence weed control that it has been patented. When wetted, it inhibits root growth of undesirables such as crabgrass, dandelions, smart weed, barnyard grass, redroot pigweed, common purslane, lamb’s quarters, and foxtail. You may not see results for a few seasons, and it requires reapplication twice a year, but the wait will be worth it. Commercial products come in an unprocessed powdery form, granulated, or in pellets.
• SPRAYS: Look for those that advertise “food-grade” ingredients or that are certified for use by organic growers. Most contain potassium salts of fatty acids, but a few new ones on the market use acetic acid (vinegar). These too are non-selective and post-emergent, meaning they kill all plant growth, not just weeds. The greatest benefit of a spray is the precise aim. In addition, there are organic products specially developed to defoliate poison ivy or eliminate moss growth.