Hot foam

Technical articles - Conserwa - Weeding

Weeding

Hot foam weeding is a thermal, non-chemical weed control method that uses a mixture of hot water and biodegradable foam to kill unwanted plants. The foam acts as an insulating blanket, allowing the heat from the water (typically around 95–100°C) to stay in contact with the weed long enough to destroy its cell structure. The plant quickly wilts and dies.

This method is increasingly seen as an alternative to herbicides, particularly in areas where chemical use is restricted or when pursuing organic or agroecological practices.

Description

1. A machine heats water to near-boiling temperature.
2. The hot water is mixed with a biodegradable foaming agent (often made from natural plant-based oils and sugars).
3. This hot foam is applied directly onto the weeds.
4. The foam holds the heat in place on the plant surface and down to the root collar.
5. The cells of the weed burst due to the sustained heat, killing the aerial parts of the plant.

For perennial or deeply rooted weeds, repeat treatments may be necessary.

Advantages of hot foam weeding

• Chemical-free: No herbicides are used, making it safe for humans, animals, and beneficial insects.
• Environmentally friendly: Biodegradable foam and no soil contamination.
• Works in all weather: Unlike some herbicides, foam weeding can be done in wet or windy conditions.
• Safe near water sources: Useful near waterways, playgrounds, greenhouses, or organic plots.
• Selective application: Allows precise targeting of weeds without damaging nearby crops or plants.

Limitations and considerations

• Fuel and energy use: Heating water consumes energy, so this method requires diesel, gas, or electric power.
• Slower than spraying: The application process is slower than chemical herbicides.
• Cost of equipment: The machines (such as Weedingtech's Foamstream or similar systems) can be expensive to buy or rent.
• Limited soil impact: The treatment kills the top of the plant but may not destroy deep roots—perennials might regrow.
• Not suitable for large-scale fields: More effective for pathways, orchard rows, vineyards, horticulture, or market gardens, rather than broad-acre crops.

Suitable use cases

• Orchards and vineyards: Under-row weed control between trees or vines.
• Vegetable farms: Particularly in organic farming for paths or row interspaces.
• Urban agriculture / community gardens: Where chemical use is restricted.
• Livestock areas: Safe around grazing zones and paddocks.
• Public or protected areas: Parks, playgrounds, and areas with sensitive biodiversity.

Cost and access

• Machine purchase: Can range from €10,000 to €25,000 depending on the model and capacity.
• Rental or contractor services: Some companies offer service-based models for smaller farms or one-off needs.
• Foam agents: Supplied as cartridges or liquid and need to be refilled regularly.

In some regions, subsidies or grants may be available for non-chemical weed control methods under environmental programs (e.g., CAP eco-schemes in the EU).