FlameWeeding: Machines

For information on the advantages and disadvantages of steam vs. flames please see visit the thermal weeder comparison page. For information on physical weeding, especially stale seed beds and thermal weeding in general please see our physical weeding information and thermal weeding pages. To discuss purchasing a flame weeder please contact Merf.


PhysicalWeeding's flame weeders are designed to get as much of the heat from the burners (torches in North America) into the weeds and let as little into the atmosphere as possible. This means that they are as effective / efficient as is practical in an agricultural setting which allows better weed control with less fuel, in a shorter time and with exceptional performance in windy conditions. Our designs are based on over 30 years practical experience using a wide range of flame weeders, from hand held to tractor mounted, as well as the full range of research from the scientific literature. The result is a flame weeder that is exceptionally effective, very easy to use and highly robust, in the best spirit and letter of the KISS (Keep It Simple Stupid) maxim.


Picture of crop-row flame weeder
PhysicalWeeding's crop-row flame weeder.

We produce all three main types of flame weeder designs: 'whole-bed', crop-row (above) and intrarow / crossover.

Crop-row flame weeders

Crop-row flame weeders treat only the crop row, rather than the whole field surface (photo above) leaving interrow weeds to be controlled using standard interrow hoes. While this approach may appear to be unnecessary complex compared with treating the whole field surface, we consider it to be superior due to the simple fact that concentrating all the available heat on the interrow means that work rates can be increased two to four times (depending on the decrease in the soil area being treated). These kind of time savings can be critical due to the small windows of time between maximum weed and crop emergence. This approach also reduces the amount of fuel used per hectare by similar values (half to a quarter) an increasingly important issue with the rising price of fuel and its impact on climate change.

Whole-bed flame weeders

Where there is a need for full width flame weeders (e.g., narrow rows or where the weeder is being used for post-crop emergence selective thermal weeding) we also produce 'whole-bed' flame weeders (below). These have easily adjustable internal hood heights (with independent front and back height control) allowing them to be used in just about any situation from pre-crop emergence flame weeding on flat beds, through raised beds, ridges, to harvesting techniques such as foliage destruction for disease management.

flamer side view flamer operating position Flamer lifted

We can therefore create a design to meet pretty much any flame weeding requirement you may have. For more information please do not hesitate to contact us.

Intrarow / crossover flame weeders

Intrarow or crossover flame weeders are the predominant type used in North America. They are used on well established row-crops with large / robust stems (e.g., maize/corn, cotton, cabbage) that can survive flaming with no or minor damage. The technique is used to suppress and/or kill smaller weeds growing in the intrarow (in the crop row) typically ones that have emerged some time after the crop was planted.

Product features

PhysicalWeeding’s flame weeder designs are the result of over three decades of our own 'real-world' thermal weeding experience and research combined with the best information and ideas from the scientific literature. We considered there to be three key design requirements for a good flame weeder:

  • maximising safety, both in normal use and should things go wrong;
  • maximising heat transfer to weeds (minimising wasted heat) to optimise effectiveness;
  • very simple to operate.


Flame weeders have a well deserved reputation as being hazardous to ignite. PhysicalWeeding have made starting our flame weeders as simple as possible. There is just one (12 volt) electrical switch situated next to the driver which turns both the gas on and off and ignites it. Turn the switch on and the flame weeder instantly starts, turn it off and the flames are extinguished. This means no more crawling around underneath the machine with paper and matches. No more pilot lights blowing out or posing a fire hazard. No more unlit burners venting un-burnt gas with all the danger that entails. Simply put the flame weeder on the ground at the start of the crop row, turn the switch on and start flame weeding. Due to the highly effective hood design there is not even a need to warm the machine up - it’s at full temperature within a few seconds of ignition. The ignition system is also continuous, so in the highly unlikely event of a flame going out, e.g., when the machine has been lifted off the ground, it will simply re-ignite, so no more concerns about un-burnt gas being vented close to working burners.

Our design also means there are no gas pipes going from the flame weeder to / into the tractor cab, which if damaged, could spray gas into and/or around the tractor, a clearly incredibly hazardous situation. The only connection between the flame weeder and tractor (in addition to the three point linkage) is a single 12 volt DC electrical cable which has a ‘rip apart’ safety connector. The same cable and the operating switch are the only parts of the flame weeder near the operator and they present a minimal hazard.

Should the worst happen, for example the tractor and machine turn over, the flame weeder is fail safe i.e., stopping the electricity supply by any means, e.g., turning off the switch, disconnecting the battery or pulling the safety connector apart will all turn the machine off. In comparison flame weeders that have gas hoses traveling between the machine and tractor are a high risk in an accident due to the hoses being pierced or severed and to turn them off requires the gas supply to be manually isolated. We can also fit non-return valves at the end of each bottle connector hose to fit to gas bottles, to provide the highest levels of safety.

Maximum heat transfer with minimum wind disturbance

Our hoods (shields) maximise heat transfer from the flames to the weeds. This is demonstrated by the fact that the exhaust gases leaving the hoods are only warm to the touch when used at the correct speed, which shows that the hot gasses from the flames are going where they are needed and not into the air. This radically contrasts with many other flame weeders where the exhaust gases exiting the hood are still very hot, clearly wasting energy. The hoods are also designed to minimise wind ingress under the hoods to negligible levels so the weeders can continue to effectively operate in strong winds. In comparison, many other flame weeders, even those with air curtains or chain baffles, can suffer significant reduction in effectiveness in windy conditions.

Simple operation.

As described above in the section on safety, operating a PhysicalWeeding flame weeder is as simple as it gets. Place the machine on the ground, turn the switch on to start the flames, then simply turn it off at the end of the row, lift the machine on the three point linkage to turn around and then start the next row. No pilot lights to manage, no banks of valves, no confusing startup or shut down procedures, not worries that a flame has gone out. Just one on and off switch. How KISS is that?

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Copyright 2009 Steam Weeding Ltd. PhysicalWeeding is a trading name of Steam Weeding Ltd. a New Zealand registered limited company.