Will a Weed Burner Kill My Weeds? An Honest Weed-by-Weed Guide

We get this phone call most weeks. Someone's looking at a paddock full of something, and they want to know before they spend the money: will one of these actually kill it?

So here's the straight answer, weed by weed. Some of it is going to talk you out of buying one, and we'd rather do that than take your money and have you ring us disappointed in a fortnight.

The one rule that predicts almost everything

A weed burner doesn't burn a plant to ash. It ruptures the cells with a split second of heat, and the plant wilts and dies over the next day or two. That means it kills whatever the plant has above the ground — and does nothing at all to what's stored below it.

So: annual broadleaf weeds that keep everything up top, it kills outright. Anything with a deep taproot, a woody crown, a running rhizome, a bulb or a tuber will come back, because you haven't touched the part that matters. Grasses are in between — their growing point sits down at ground level where the heat struggles to reach, which is why flame works better on broadleaf weeds than on grasses.

One more thing worth knowing up front: a weed burner is completely non-selective. It kills whatever it touches. That's perfect on gravel and paths, and a problem in the middle of a lawn you care about.

Learn those two rules and you can predict the answer for any weed on your place, including ones we haven't listed.

The short version

Weed Will a weed burner kill it? What we'd actually do
Capeweed Yes Hit the rosettes in autumn/winter before they flower. One of the best jobs this tool does. Full article
Fireweed Yes, until it flowers Kill seedlings and rosettes on sight. Once it's flowering, bag and remove instead — the seed is wind-blown. Full article
Paterson's Curse Yes, while small Small rosettes die outright. Big ones build a stout taproot and may push back — expect a second pass. Full article
Bindii / jo-jo Yes, but not in lawn Kills it easily — but flame is non-selective and will scorch your lawn with it. Right tool in gravel and beds, wrong tool through turf. Full article
Thistle seedlings Yes, while young Easy while small. Once the taproot is established you're into repeat treatments.
Driveways, gravel, pavers, fencelines Yes This is the single best job for a weed burner. Nothing to damage, no chemical runoff, no re-entry period.
Blackberry Not on its own Won't kill an established crown. Cut it first, then flame the regrowth repeatedly to starve the crown. Kills seedlings fine. Full article
Lantana Not on its own Resprouts from base, roots and fragments, even after fire. Excellent on seedlings, suppression only on established bushes. Full article
Paspalum Suppression only Regrows from a crown full of short rhizomes. Good for holding an edge and stopping seed heads; dig the crown out to kill a plant. Full article
Couch & kikuyu Suppression only Runners survive. Useful to knock it back off a path edge, not to eradicate it.
Serrated tussock Poorly Growing point sits protected at ground level. This is a job for other methods.
Nutgrass No Growing point sits 7–18cm underground and tubers stay viable up to 10 years. Don't buy one for nutgrass. Full article
Onion weed No Bulbs survive. Same problem as nutgrass.
Bracken fern No — and it can backfire Bracken is adapted to fire. Burning it can leave you with more of it, not less. Full article

If you've got animals, read this bit

Several of the weeds above — fireweed, Paterson's curse, lantana and bracken — are toxic to stock, and in most cases killing the plant does not make it safe. Dead and dried material stays poisonous, and contaminated hay is one of the most common ways animals get a dose. Risk climbs sharply in a dry year or an eaten-out paddock, when animals will eat things they'd normally walk past. If you think an animal has been getting into something, that's a vet call.

Capeweed — yes, and it's one of the best jobs for it

Capeweed is an annual. It germinates in autumn, sits as a flat rosette through winter, then flowers and sets seed in spring and dies. Everything it owns is above the ground, in that rosette. Which makes it just about the perfect target.

Run over the rosettes in autumn or winter and they're finished. The trick is timing, not power — get them before they flower. Once it has set seed you've won the battle and lost the war, because you'll be doing the same thing again next autumn with a bigger seed bank.

Two things that matter as much as the burner: don't overgraze into late summer, and don't leave bare patches going into autumn. Capeweed is an opportunist — it moves into bare ground. A thick pasture is the actual long-term fix, and the burner is how you clean up while the pasture thickens.

Read the full capeweed article →

Blackberry and lantana — not on their own, but they have a real job in the program

Here's the honest position. An established blackberry has a woody root crown that's been building for years, plus lateral roots that sucker, plus canes that root wherever the tip touches ground. Lantana does the same thing and resprouts after fire as well. A pass with a flame weeder takes the leaves off. The crown doesn't care.

Where it genuinely earns its keep:

  • Seedlings. Kill them on sight and you stop next decade's thicket.
  • Regrowth after cutting. Cut or slash the thicket, then flame the soft regrowth every few weeks. Every time the crown pushes new growth it spends stored energy, and every time you take that growth off before it can pay itself back, the crown gets weaker. Do that consistently and you exhaust it.
  • Edges and re-invasion. Keeping a cleared boundary clean so it doesn't creep back in.

What doesn't work is one heroic afternoon with a torch. Both of these are multi-season jobs with any method, chemical or not. Anyone who tells you otherwise hasn't done it.

Read the full blackberry article →  |  Read the lantana article →

Bracken fern — don't buy a weed burner for this one

We'd rather say this plainly: if bracken is your main problem, a weed burner is the wrong tool, and it may make things worse.

Bracken has deep underground rhizomes that are completely out of reach of surface heat. Worse than that, it's a plant that has evolved with fire. It throws up a layer of dry dead fronds that carry a burn, and afterwards its rhizomes shoot back hard and fast — usually faster than whatever was competing with it. So you can burn a patch of bracken and hand it an advantage.

What actually works on bracken is repeated removal of the fronds — cutting, slashing or rolling — done consistently over two to three years, so the rhizome slowly runs out of stored energy. Then get something else established in that ground so the bracken doesn't simply walk back in.

One more thing worth knowing if you've got stock: bracken is toxic to horses and cattle, and the risk goes up when there's not much else to eat.

Read the full bracken article →

Nutgrass — the one that makes people think the tool is broken

Nutgrass keeps its growing point in a basal bulb roughly 7–18cm below the surface, and banks chains of tubers that stay viable for three to four years and sometimes up to ten. Take the leaves off by any method and the growing point simply sends up more.

Worse, cultivating it breaks the tuber chains and spreads them. Plenty of people have turned a patch into a paddock with a rotary hoe. If nutgrass is your main problem, don't buy a burner for it.

Read the full nutgrass article →

So what is a weed burner actually for?

Put simply: annual broadleaf weeds, young growth, and anywhere you can't or won't spray. Driveways, gravel, around tanks and sheds, along fencelines, between beds, around the house where the kids and the dog are, and paddock weeds caught early at the rosette stage.

Used for that, it's the fastest chemical-free tool we know of, and there's no licence, no withholding period, no runoff and nothing to keep animals off. Used as a magic bullet on a woody perennial, a running grass or a tuber-former, it'll disappoint you — and we'd rather tell you now.

Not sure about your particular weed?

Ring us on +61 449 268 131 and just tell us what you're looking at. If a weed burner is the wrong tool for it we'll say so — we do it most weeks. And if you do buy one and it doesn't clear what we said it would, our 30-Day Weed-Free Guarantee means you get your money back.

SEE THE WEED BURNER RANGE

General guidance based on how thermal weeding works and on published weed biology. Weed identification and control obligations vary by state and council — several of the weeds above are declared and carry legal control requirements. Always check your local council or state agriculture department, and check current fire restrictions before you use any open-flame tool. Nothing here is veterinary advice; if you're concerned about an animal, ring your vet.

MICRO GREENS