Posted on

burning weeds before seeding lawn

Is Burning Weeds Better Than Roundup?

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.

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.

Roundup in the Garden

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.

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.

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.

Torching Weeds in Rocks

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.

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.

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.

Weeds and Cultural Controls

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.

Removing weeds before they can go to seed eliminates new seedlings. Mow the lawn at the recommended height to encourage thick turf that crowds out weeds. Alternately, you can accept a certain level of attractive natives and spring-flowering plants like violets (Viola spp.) and dandelions (Taraxacum spp.), hardy in USDA zones 3 through 9 and 10, respectively.

In addition, a thick layer of mulch reduces weed seed germination while conserving water. You can add a drip irrigation system to put water over the desirable plants’ and shrubs’ root balls while leaving the weed seedlings to dry up in the hot summer sun.

What you should know before you take a flamethrower to weeds

Don’t let anyone convince you the gardening is all grandmas and fresh produce: sometimes there are flamethrowers involved.

Flame weeding, often called “flaming,” is one method for natural weed management by passing a flame over a weed briefly to heat the plant tissues just enough to kill them. The plants will start to look dull and wilt a bit. The method can be effective — and, let’s be honest, awesome — but it also isn’t appropriate for every situation.

“It works really well in certain situations,” said Kate Garland, horticultural specialist at the University of Maine Cooperative Extension. “It can work really well on young [weed] seedlings, [on] gravel driveways or walkways free of organic debris that’s flammable.”

Flaming is a less effective weed control method for perennial weeds, which have extensive below-ground root systems from which new weeds can emerge even after the above-ground portions have perished.

“It kills the cell on the above ground portion of your weeds,” said Sonja Birthisel, postdoctoral research associate at the University of Maine. “Some species are more resistant to death by heat than others. If you have perennial weeds you might need a little bit higher propane dose or go back over it multiple times.”

The technique can work in backyard vegetable gardens if you want to kill a flush of early weeds prior to planting, Birthisel said.

“You can do this by tilling the soil and waiting for a first flush of weeds to come up and using a propane torch and flaming a couple of weeks before planting,” she explained.

Advantages and disadvantages to flame weeding

The advantage to using the flame weeding method over other natural weeding methods is its efficiency.

“It can be pretty quick,” Garland said. “If you have a cropping system where you have pretty small seedlings and you can catch them early and do it frequently, it is a fast way of weeding.”

One of the downsides to flame weeding in gardens is that it’s hard to expose the weeds to the flame without exposing your crops as well, but it is possible to work around this through timing and careful application of flaming.

“I would recommend doing it before you plant, or using it very carefully between plants or in the rows between your beds if you want to control later season weeds that way,” Birthisel said. “Just know that there’s a danger of getting that flamer too close.”

Plus, it is not especially environmentally-friendly because it utilizes fossil fuels.

“If you are fossil fuel conscious, it could be that mulching is more appropriate,” Birthisel said.

When not to flame

There are certain scenarios where flaming is not appropriate.

“It would be totally inappropriate to use this method near things that are potentially flammable. If you’ve got a brush pile that would be out of control if it went up in flames,” Birthisel said. “I’d be hesitant about using this practice if I lived in Southern California or a place that’s prone to wildfires. I would recommend people check with their local ordinances before applying this practice.”

Birthisel also strongly cautioned against burning poisonous or noxious weeds like poison ivy. The results can be painful, both for the person weeding and those breathing the air around them.

“When you burn poison ivy, it can get those noxious compounds up in the air,” she explained. “People can inhale them and have really nasty issues with getting poison ivy in [their] lungs.”

Choosing a torch

A flame weeder generally consists of a wand connected to a propane tank by a hose accompanied by some sort of dolley or carrying apparatus.

“I have a backpack model that’s basically a pretty similar propane tank mounted on a backpack,” Birthisel said. “I walk and use [it] to torch weeds. That’s pretty popular and I see backyard gardeners and farmers using that.”

Another popular model is basically a propane tank on wheels with a torch attached, Birthisel said. She recommended shopping around for different models to see what is most comfortable and accessible to you.

“And, of course, read up and make sure you’re following the directions on any flame weeder that you buy,” she added. “I have seen issues where people accidentally set a bush on fire, so handle with care [and] have the hose nearby.”