Flaming – Eric McLenaghan


Flaming can be a viable option for in-crop weed control in some crops. Flaming is accomplished by using a small directed flame created using liquid propane or natural gas. The flame burns small weeds, killing them while not harming the crop. The flames are positioned between the rows of crops to ensure good control.

Fine Tuning

Flaming is the most effective when the crop is much larger than the weeds. This allows the crop to grow through any damage that occurs. Weed seedlings need only be exposed to the flame for a very short time, but the process is much more effective against broadleaf weeds rather than grasses. This is due to grasses growing point being below ground, while broadleaves being above.


It is better to use flaming in grass crops rather than broadleaves, due to the same reason flaming is more effective on broadleaves. The best way to experience control is to use flaming on broadleaf weeds in a grass crop. To experience full control it is necessary to make several passes during a growing season. Timing flame control is crucial, as it is most effective when leaves are 1-2 inches tall or in the 3-5 leaf stage. Using this particular weed control method can be risky in fields with lots of crop residue, especially in years where rainfall is scarce.


Costs associated with flame weed control can be substantial. Since equipment is rare it can be expensive to purchase and to fix. There is also the cost of propane or natural gas, of which the prices of both are rising.

Personal Opinions

Flaming looks like it could be a useful alternative for some producers. If using this method, I would think GPS is a must, and this method is likely most effective if used in conjunction with controlled traffic farming.


R.W. Heiniger. 1998. Controlling weeds in organic crops through the use of flame weeders. Organic Farming Research Foundation Project Report. Online. Available: http://ofrf.org/funded/reports/heiniger_94-43.pdf. Accessed: March 12, 2014.

Mutch D., Simmons J., Monroe J., and Gene Vogel. 2005. Some helpful tips on flaming weeds in corn and soybeans. The New Agricultural Network. 2. 3.


Flaming – Cameron de Wolf

Introduction: This technique of weed management is fundamentally defined as causing plant death by the exposure of plants to temperatures that are substantially higher than those which are optimum for plant growth and physiological factors. The main target of this type of weed management is the disruption of cellular functions, processes, and membranes, not the actual physical scorching or wilting of a plant. It can be used to minimize or eliminate soil disturbances (ex. tillage) in a variety of soil conditions. This method is typically used in smaller scale, high value vegetable production and is not prevalently used in North America. It can be quite effective, if applied correctly and efficiently.  

Source: Image Link https://www.flameengineering.com/files/categories/category_9.jpg


Fine Tuning: This method is most efficacious if applied in a stale seedbed situation. In this way, weed control can occur right until crop/plant seedlings emerge. Correct timing is very critical in making this method effective. It is most effective when weeds are small (1-2 inches), and in warm conditions (as in cool conditions, most “warm season” weeds may not have germinated).

Considerations: Flaming does not work very well if the soil surface is rough or rolling. Therefore, the land/soil should be well prepared, flat, and level for flaming efficacy to be optimal. Safety should also be kept in the forefront with this method. Open flame, extremely high temperatures, and combustible/flammable fuels are being used in combination. These aspects are dangerous, and the necessary precautions should be taken to make flaming as safe as possible (shielding, limited dry residue, protection, etc.).

Costs: Costs will vary largely on the type of unit purchased or built. There is a large range of units available, including single torches, multiple torches on a hand-push unit, or tractor-powered flaming kits (hundreds to thousands of dollars). It also depends on the type of fuel being used, as these prices differ from each other and can fluctuate to a large extent (diesel, gasoline, propane, natural gas, etc.). The ecological cost of this method can be viewed as lower than that of other techniques. To a large extent, soil organisms are not affected by flaming, and the soil/environment is not being disturbed.

Personal Opinion: Flaming can be a viable weed management option if all the related factors to its efficacy are considered. As well, perennial weed control may not be effective because they regrow quickly. Some weeds may also be able to tolerate heat better than others. Flaming can be a versatile, useful technique, if used in the correct manner.


Weed Flaming – Austen Preete

Flame weeding involves the use of a fuel-burning device, either hand held or tractor-mounted, to kill weeds due to intense heat. This method usually relies on propane gas burners because it can produce controlled and directed flame that will briefly pass over the weeds. A brief flaming will damage the cell structure of the foliage, which will cause cell sap to expand and disrupt the cell walls. Within a day or two the weed will wilt and die (Grubinger. 2004).  This technique is used to kill young seedlings, usually annual broadleaf weeds, before the crop emerges.  Flame weeding can be an effective approach to eradicating early weed flushes.  It can be used in-row in certain crops such as corn and onions in which the bud is protected inside a whorl of leaves that can tolerate a light flame, even after the crops are established. In addition, cereal crops that have their growing point below ground or have a protective sheath covering the growing point, can sustain a brief amount of flame without suffering internal damage (Cornell. 2004).

Using a stale seedbed approach will offer the best conditions to reap the most effective results. The stale seedbed practice causes the longest delay between emergence of weeds and the emergence of the crop itself. Therefore, giving the grower an adequate amount of time to make a number of passes on the weed population without concern of damaging the incoming crop. Conditions for flaming also becomes ideal when a slow emerging crop such as carrots is sown (Grubinger. 2004). Hot and dry conditions will positively affect the performance of flame weeding because the weeds themselves are already lacking moisture (Cornell. 2004).

Avoid flame treatments on tough to kill weeds, such as perennials, because the plant has stored energy in the roots or stems that allow them to re-grow after a single flaming. This problem may be mitigated by additional tillage after several flame applications when the weed is weak and has exhausted the majority of its resources (Grubinger. 2004). Problems with using the flame weeding technique can be avoided by planting cultivars of species that germinate later in the spring to allow for a substantial amount of weed removal time before the crop emerges. Ensure to flame weed seedlings early to avoid the plants surviving because they are too developed.

On a large scale production farm, flame weeding can be expensive because the implement required to be towed behind the tractor is an expense, as well as the constant propane refills. Flame weeding is relatively straightforward, but it does deal with an open flame that can inadvertently ignite surrounding dry plant material. It is recommended to use the practice in the morning while the dew can maintain moisture on the plant. Also, a grower must not flame poisonous plant material because the smoke may cause irritation and ill effects to the lungs and eyes (Grubinger. 2004).

The value of this technique is more practical on a smaller scale because the grower can be more selective; therefore, using less propane and applying inter-row applications carefully while the crop is emerged. Unfortunately, it is a time consuming technique because more developed weeds require more than one pass to eradicate. Also, weed species, such as grasses and perennials, are difficult to kill while using flame weeding as the lone technique. The concept is adoptable since it does not cause ecological damage to the soil, but the relative ineffectiveness against all weed species will be viewed as a major disadvantage regarding this technique.

Cornell University. 2006. Weed Ecology and Management Laboratory: Flame weeding.  https://weedecology.css.cornell.edu/manage/manage.php?id=4

Grubinger, V. 2004. University of Vermont. Flaming stale seedbeds for weed control.  http://www.uvm.edu/vtvegandberry/factsheets/flameweeding.html


Flame Weeding – Travis Ebens

Flame weeding is a management technique that applies a high amount of heat to weeds for a couple of seconds. This kills the plant by causing the cell sap to expand and damage the cell walls, leaving the plant incapable of moving water up from the roots.  Heat is applied approximately three to six inches above the crop (Cohen, 6).

Weed flaming has two main uses.  The first use is for killing weeds in row-crop crops.  Tractors with three-point-hitch mounted units travel through row crop fields and apply heat to the weeds between the crop rows (InterRow Burners).

Figure 1: Interrow flame weeder. Source: Image Link http://www.hoaf.nl/images/stories/groenbeheer/lay-out/hoaf-twin-sprite-12.jpg

The second use for weed flamers is to kill weeds before seeding.  This can be done with an open model three-point-hitch mounted unit.  This unit can be used on land that is going to be used for either row crop or non-row crop crops.

Figure 2: Open model flame weeder. Source: Image Link http://www.kress-landtechnik.de/wEnglisch/produkte/gemuesebau/hacktechnik/abflammtechnik/img_Abflamm/titel3.jpg

Flame Weeding is most effective when plants are still seedlings.  Burning the cotyledons before true leaves develop is the most beneficial flaming technique (Organic Weed, 2008).   Grasses can be quite resilient to this technique and may require multiple passes.  This is because the crown is often beneath the soils surface and not exposed to the heat (Organic Weed, 2008).  Broadleaf weeds are easily killed as seedlings (Grubinger, 2004).

The optimal condition for flame weeding is shortly after a rain.  This allows the plant cells to fill with water (Organic Weed, 2008).   As well, this reduces the risk of fires.

Some of the downfalls to flame weeding is that the equipment is not mass produced which makes it difficult to attain, the propane cost can be expensive, dealing with open flames can be dangerous and the majority of this equipment comes from Europe.

Overall, I think flame weeding is an excellent way to control weeds.  It can be done quickly with large equipment and recent technological advances such as self-igniting systems have made this method both safer and more convenient.  As well, I believe the biggest advantage is that both organic and nonorganic farmers are using this tool because of their discontent with herbicides and herbicide resistance.I wasn’t able to find any financial information for this technique.



Cohen, Brad. “Flame Weeding: A Hot Alternative to Herbicides.” Journal of Pesticide Reform 26 (2006): 6-7

Grubinger, Vern. Flaming Stale Seedbeds for Weed Control. http://www.uvm.edu/vtvegandberry/factsheets/flameweeding.html. Accessed Mar. 7 2014.  University of Vermont. 2004.

Inter Row Burners.  http://www.hoaf.nl/index.php?option=com_content&view=article&id=26&Item id=201&lang=en.  Accessed March 7, 2014.  HOAF In

Organic Weed Control Tips on Flaming: Weed Em and Reap. Youtube Video, 4:41. Posted by “eOrganic,” Nov. 7 2008. http://www.youtube.com/watch?v=OCQJh3J4pAw.