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does burning weeds kill the seeds

A quick pass with the torch and you’ll see weeds wilt and die.

A thumb print on the weed leaf indicates success.

For help troubleshooting your weed burner, check out more on the FAQ page !

What’s the best advice we can give you? If in doubt, don’t. Always allow a safe distance between the flame and desirable plants, shrubs and trees. Always keep a fire extinguisher and water supply close in case of an emergency. Contact your local city or fire department to see if it safe to run a flame weeder in your area.

Flame weeding is what we like to call a “slow kill”. Essentially, you are destroying cell structure in the plant leaf. The weed will no longer put energy toward growth (photosynthesis) taking the kill though the root system. YES, flame weeding will kill the roots too! Even on big weeds (over 6″), you will see a stunting effect and even a kill within a few days, depending on how established the root system is and how long the plant was exposed to heat. Again, multiple application may be necessary for well-established pants. When you see green – flame!

You do not want to burn weeds to ash! On smaller weeds, a slow walk is usually the best pace – just a split second of heat should kill unwanted weeds and grasses completely – you don’t need to burn them to a crisp. By nature, some grasses will return following a flaming. Repeat applications, however, will usually do the trick. For best results, increase exposure to the heat if weeds are wet from dew. Water on the leaves acts as insulation and decreases cell damage unless exposure time is increased. Note: it is ok to flame when it is wet out. In fact, we recommend it. Moisture will lessen the threat of ignition of dry debris.

When flame weeding, the most effective method is to catch weeds early, from 1-4 inches. At this small stage, flaming is nearly 100% effective at killing weeds, whereas weeds over 4 inches are more difficult to kill without multiple flamings.

It is important to remember when flaming in and around desirable plants that heating those leaves can cause damage as well. Flame is not like a broadleaf herbicide in that it will only kill the weeds. Fire does not know the difference between desirable flowers and undesirable weeds. Thus, be careful around flowers and shrubs – particularly evergreens. Conifers are very flammable and should be avoided at all costs! Poison ivy, oak or any poisonous plant should be avoided also- the vapor/smoke from flamed leaves will cause a rash to your skin, eyes, and lungs! Yuck!

Most flamers include valves that allow you to adjust the flame from low to high settings. How much fuel you use will depend on the size of the burning tip and your flame-adjustment setting. Typically, a 5-gallon gas tank will provide enough for 3 to 6 hours of burning. However, a flamer with a 3-inch tip at full throttle will burn 20 pounds of fuel (about 5 gallons) in an hour.

Burning Time

For a flame that starts safely and easily, look for one that has an ignition switch. These devices send a spark directly into the torch. You simply turn on the gas, hit the switch, and you’re on your way. Not all flamers are that easy to start, though. Many manufacturers provide flame-starting tools that you must hold near the gas outlet. These devices generate sparks that ignite the gas. They are simple and safe when used properly. Don’t use matches because your hands will be too close to the flame when it ignites.

Flamers are long metal tubes that carry gas to the flaming tip. The function sounds simple enough, but some products have features that make weeding both easier and safer.

For effective weed control, use flamers in spring and early summer as annual and perennial weeds emerge. Killing larger, mature plants requires more heat, so save time and fuel by flaming weeds when they’re still young and tender.

Flamers are portable gas torches that produce intense heat (about 2,000°F). When you pass the flame over and around weeds, it quickly boils the water in the plants’ cells, causing them to burst. Once the heat destroys any section of a weed’s stem, for instance, water and nutrients cannot reach the leaves, and the top part of the weed dies.

Lanine and Orzolek both recommend using flamers as a pre-emergence control. Most viable annual weed seeds are in the top 1/4 inch of soil, and flamers can kill already-germinated seeds with heat.

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.

Roundup in the Garden

Weeds – the bane of nearly every gardener’s existence. While reaching for the Roundup is one option, you may consider burning weeds instead. Flame weeding is an organic method of weed destruction and removal, but be careful with the open flame. You don’t want to risk starting a wildfire when working in hot and dry conditions.

Glyphosate is the active ingredient in several nonspecific herbicide products, including Roundup. It is absorbed by the plant’s leaves and moves through the plant down to the roots to destroy the weed. As the National Pesticide Information Center points out, glyphosate interferes with the shikimic acid enzyme pathway, which prevents essential protein production in plants. It is nonspecific, so it will also affect nearby plants if you spray on a windy day.

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.