How can flame weeding be used to control weeds?
Flame weeding is the use of intense heat, usually produced by a propane torch or other fuel-burning device, to kill weeds. This organic option for weeding causes the water and sap inside the plant cell to boil and expand rupturing the cell walls and causing the plant to wilt and die.
The goal is not to ignite the weeds on fire. Instead, plants are subjected to a brief, intense heat the causes the cell walls to burst. Immediately after exposure plants will turn a dull green and wilt slightly. Over the next several hours to days weeds will wilt completely and die.
Flame weeding is most effective on small, young plants. Broadleaf weeds are more completely controlled with this method than grasses as many grasses have growing points just below the ground or protected by a sheath that are not adequately killed by the heat of the torch. Perennial weeds or those that are well established will require multiple applications approximately every two weeks to kill newly emerging growth and exhaust the root system, fully killing the plant. Often using flame weeding in conjunction with other methods of weed control, like cultivation, is more effective on perennial weeds than utilizing flame weeding alone.
Flame weeding is a particularly effective form of weed control in areas where desirable plants are not nearby, such as in the cracks of driveways and patios or when utilizing the stale seedbed technique for weed management. Flame weeding is non-selective, impacting any plant nearby. For home gardeners, commercially available flame weeder devices can be used, as can handheld propane torches. When utilizing propane torches, be sure to use those that can be operated upside down, such as those designed for use in plumbing, to make the application easier.
Safety is of the utmost importance with flame weeding. Always use equipment as directed and do not flame weed on windy days. Never use torches around dry grasses or other materials that could easily ignite. Wear appropriate clothing to protect yourself from the heat and flames.