Organic Ways to Manage Weeds
Hand-pulling and mulching
Manual controls such as hand-pulling and mulching are where to begin when tackling weeds. Hand-pulling has an element of satisfaction that no other weed-control method can offer. It's also one of the few ways for selective control. Hand weeding is easiest after a soaking rain. With tap-rooted weeds, make sure to get the entire root. Otherwise, any remaining piece will provide sufficient energy for it to regenerate a new plant. A layer of mulch 2 to 4 inches thick is a very effective organic means of preventing most weeds from germinating. To be sure the bagged mulch you buy is free of potentially harmful contaminates such as arsenic from treated wood, check each bag for the certification seal of the Mulch and Soil Council.
Sprays and drenches
A second option are sprays and drenches, which affect plants on contact by burning or desiccating the cell structure. As a contact herbicide, they are most effective on young annual weeds.
Boiling water works well at killing most weeds with one application. Some weeds, especially those with tap roots such as dandelions, may need multiple applications. Use caution and keep the water as close to the weed as possible to avoid splashing yourself or other desirable plants.
Acetic acid also works, but common household vinegar is not effective for mature weeds. Minimum concentrations above 7 percent are needed to manage tougher weeds, and multiple applications may be necessary with tap-rooted weeds. Use caution when using acetic acid, as it can burn skin and eyes on contact. Approved sources for herbicide use can be found online or at farm-supply stores.
Plant-based ingredients such as citric oil, clove oil and garlic are non-selective post-emergent herbicides. Use caution, as they will injure or kill all vegetation they touch. Again, tougher weeds usually require multiple applications for complete control. Ready-to-use products are available through organic gardening-supply sources online and in some garden centers.
Granular Pre-emergent Corn Gluten is a granular corn-based product that is used as an organic pre-emergent control in lawns. Although effective, it takes several seasons for results comparable to synthetic options. Corn gluten has the added benefit of containing 10 percent nitrogen by volume for natural fertilization as well. It is becoming more popular but is not yet widely available in retail garden centers. It is readily available online.
Flame weeders are devices that use the intense heat of a concentrated flame to destroy the cell structure of the plant. Typically powered by a propane canister, they are portable and effective. Simply pass the flame over the weed for several seconds. It is not necessary to visibly burn the weed, and a few seconds of intense heat is all that is necessary. Like the other methods listed above, because the roots are unaffected, the toughest weeds may require multiple applications. Use extreme caution when working with this tool.
Prevention is the best way to reduce the weeds from spreading next year. Although they will still come into the yard through other means, eliminating weeds on your property before they go to seed or have a chance to spread will save many hours of work next year and beyond.