Gardeners looking for a safer option for controlling weeds may now have just what they need ? right in their own pantries. USDA researchers in Beltsville, Maryland, found that vinegar killed 80 to 100 percent of several major weed species, including common lamb's quarter (photo at right), Canada thistle, smooth pigweed, velvetleaf, and giant foxtail. It kills the top growth, so repeat applications are needed for perennial weeds. Nevertheless, the safety and effectiveness of vinegar holds great promise for gardeners wanting to reduce dependence on chemicals for managing weeds.
Researchers tested vinegar at concentrations of 5 percent and 10 percent. Both killed weeds less than 2 weeks old, but older weeds required higher vinegar concentrations, such as 20 percent. (Household vinegar is approximately a 5 percent concentration.)
BurnOut Weed & Grass Killer is one of several commercial products that feature vinegar as their active ingredient. You can order BurnOut from Planet Natural or the Biocontrol Network.