An alternative to both Roundup and burning weeds is using cultural controls in the garden. Hand weeding and careful cultivation with a hoe around existing plants reduces the number of weeds in the landscape. However, digging deeply when removing existing weeds or adding compost and other amendments to the garden bed also exposes buried weed seeds, warns the University of California IPM Program.
When weeds are embedded in the cracks of concrete sidewalks and driveways or sprouting amid gravel mulch or walkways, using a flamer is one method of weed removal. Even if weeds have developed resistance to herbicides, flame torching affects the plants’ cell membranes with high heat. You aren’t actually “burning weeds”; instead, you’re disrupting the plants’ ability to function by the application of targeted high temperatures.
Flame weeding is considered an organic method of weed removal. However, if the weather is hot and the fire danger is moderate to extreme, Roundup may be the better option to avoid accidentally starting a fire or risking fines from the local fire district or other government agency.
Torching Weeds in Rocks
While other methods of weed control avoid the use of herbicides, Roundup may be the necessary choice when eliminating invasive plants or weeds that are a health risk to humans and pets. The highly invasive kudzu (Pueraria montana) and toxic poison ivy (Toxicodendron radicans) and Pacific or Western poison oak (Toxicodendron diversilobum), hardy in U.S. Department of Agriculture plant hardiness zones 5 through 10, 3 through 10 and 4 through 8, respectively, are prime examples of persistent and difficult-to-control weeds that may require the use of herbicides.
When using a flame weeder, you should put on closed-toe shoes, long pants, safety goggles and other safety gear as recommended by the manufacturer. Torching weeds is a matter of applying high heat but not actual fire. If flames are visible, you may be walking too slowly; dry plant matter or bark mulch is in the treatment area; or you’re holding the weeder too close to the weeds. Use caution when the weather is dry and/or windy to avoid starting a fire.
Before using any glyphosate product, take the time to read the instructions carefully. Put on protective gear, including goggles, gloves and a dust mask, to protect your eyes, skin and lungs. Wait until the weather is calm, not windy; overspray can affect nearby desirable plants. Spray only the weed until it is wet, but not dripping. Keep children and pets out of the treated area until the herbicide is completely dry.
If you’re using organic methods in the garden, flame torching is an approved method of weed destruction. The University of Minnesota Extension points out that flaming works best on young and broadleaf weeds, especially when applied at least twice per growing season.
Weeds only need a 1/10 second exposure to the flame, so pass the flame slowly over the weed. If you are weeding rows in a vegetable garden or along a fence line or drainage ditch, walk slowly, about 1 or 2 miles per hour (2 km. per hour) along the area you want to flame. Be careful to keep the flame away from the hose that connects the propane tank to the wand.
The problem with flame weeding in gardens is that it’s hard to expose the weeds to the flame without exposing your plants as well. In vegetable gardens, use a flame weeder to kill weeds that emerge after you sow seeds, but before the seedlings emerge. You can also use it to kill weeds between rows.
If the idea of weeding using a flame thrower makes you uneasy, it’s time to find out more about using heat to kill weeds. Flame weeding is safe when you use the equipment properly. In fact, in many cases, it’s safer than using harsh chemicals that can contaminate groundwater and leave toxic residue on your garden vegetables. Read on to learn how to use flame weeders and when flame weeding is suitable.
How to Use Flame Weeders
Flame weeding kills some annual weeds for good, but perennial weeds often regrow from the roots left in the soil. Perennial weeds require several treatments at two to three week intervals. As with any weeding method, if you kill back the tops often enough, the weeds eventually give up and die.
Once you have passed the flame over the weed, the leaf surface changes from glossy to dull. If you are concerned that the weeds aren’t dead, allow them to cool and then squeeze a leaf between your thumb and finger. If you can see a thumbprint in the leaf, the flaming was successful.
A flame weeder setup consists of a wand connected to a propane tank by a hose. You’ll also need a dolly to carry the propane tank, and a flint igniter to light the flame if the wand doesn’t have an electronic starter. Read the instruction manual completely before using a flame weeder.
Flame weeding entails passing a flame over a weed briefly to heat the plant tissues just enough to kill them. The goal is not to burn up the weed, but to destroy plant tissue so that the weed dies. Flame weeding kills the above ground portion of the weed, but it doesn’t kill the roots.