Weeds cause an unsightly mess and can damage sidewalks or driveways by creating and expanding cracks. Most weed killers use toxic chemicals that may harm pets or humans as they kill the weeds. Household vinegar is an inexpensive, pet-safe, child-safe effective herbicide that doesn’t run off into waterways or persist in the soil to pollute the garden ecosystem.
Step 1: Proper Weather Conditions for Killing Weeds with Vinegar
Vinegar must stay on the plant for several hours or days to be effective. Choose a time to treat weeds when no rain is expected for several days. Rain washes the vinegar off the leaves and flushes it from the surrounding soil before it can do its work. Watering or irrigation can also flush the vinegar away from the weed prematurely, so avoid watering plants in the area near the vinegar-treated weed.
The hotter the weather, the better vinegar works. With dry conditions and temperatures above 90 degrees, you may see wilt within an hour. In cooler temperatures, weeds treated with vinegar may stay green for several days.
Step 2: Applying Vinegar to Weeds
To kill a weed with vinegar, spray the entire plant with 5 percent vinegar, using a spray bottle or hand sprayer. You can also paint the vinegar on the plant with a brush. Cover both sides of every leaf and wet the stem well, too. Pouring a cup of vinegar around the base of a weed can help kill the roots.
Any type of 5 percent acidity vinegar will work, Distilled white vinegar is generally the least expensive. Vinegar has a distinct odor, which will permeate the area being treated. The smell dissipates quickly.
Step 3: Reapply Vinegar as Necessary to Weeds
Weeds killed with vinegar turn brown and die. Stubborn weeds, particularly thistles and perennial weeds, may require more than one application to achieve total kill. If a weed is still partially green in a week, apply the vinegar again. These weeds may also respond to higher concentrations of vinegar; however, homeowners may not be able to readily purchase vinegar stronger than 5 percent acidity.
Because vinegar does not persist in the soil, it does not affect seeds or plants that sprout after the application. These weeds require additional vinegar applications.
Step 4: Composting Vinegar-Treated Weeds
Most herbicide applications make a weed unfit for the compost pile, since the weed killer residue on the plants may contaminate the resulting compost and damage plants. However, weeds treated with vinegar can be safely added to a composter in limited quantities.
Vinegar is non-selective; it will damage any plant it contacts. Though broad-leafed weeds are most susceptible, vinegar will also kill grass and desirable plants. Shield plants you wish to keep to prevent overspray from affecting them.
Use caution when using vinegar to kill weeds growing through cracks in concrete. One or two applications won’t harm the concrete, but repeated exposure to the acid may eventually corrode cement.
The acidity of vinegar can damage the spray mechanism of backpack or hand sprayers. Always empty and thoroughly rinse the spray applicator after using vinegar.