The media have demonized weedkillers in the agricultural sector so much that we no longer know how to remove weeds from our garden. Update on the reality of the products and the best practices to adopt thanks to Patrick Mioulane, President of Promojardin and garden journalist.
What are weed killers on the amateur gardening market today?
There are mainly chemical weedkillers. The leader is Roundup, whose concentration of active ingredient is extremely low compared to the products used in the agricultural field. Sodium chlorate has also been used for a long time, but it is starting to be banned because it can be used as a derivative (note: it can be used to make bombs).
Are chemical weed killers really dangerous for the environment?
Today's weedkillers contain ten times less toxic molecules than 20 years ago for even greater effectiveness. And that will continue to improve as chemistry continues to make progress. Which doesn't stop you from being careful. If the product is not over-concentrated, the site will not be polluted. However, certain rules must be observed: do not use it near an aquatic area, or on very porous soil such as sand because in the event of heavy rain, the product will enter deeper into the soil up to the water table. Avoid also spraying an impermeable surface with weed killer. Indeed, in this case, the product trickles and concentrates where it is not necessary. Another thing to know: it is better to avoid weeding with a watering can and prefer a sprayer, which deconcentrates about 20 times the product.
Are thermal weeding and hot water weeding good alternatives?
Thermal weed killers must be used correctly so as to burn only the plant and not the surface layer of the soil. To do this, pass the burner over the upper part of the leaves, about 10 cm from the ground. It is an effective means, but it is not frankly ecological. Indeed, petroleum gas requires a lot of energy to be manufactured and then transported. In addition, it generates CO2 when it burns. The ecological footprint of thermal weeding is therefore significant. As for weeding with hot water, with hot water from potatoes that have just been cooked, for example, it is only to be used on uncultivated areas. In fact, hot water destroys all of the microfauna present in the first layers of the soil and which are very important for the fertility of the earth.
What are the most ecological methods of weeding?
Nothing beats the hoe, weeder or weeding knife. We are awaiting the approval in France of a weedkiller of natural origin, Finalsan, which is made from a South African pelargonium. It is already on sale in Belgium, Luxembourg and Germany. It has the advantage of breaking down into fatty acid molecules, which are found naturally in nature. This product therefore has no harmful effect on the environment. But to be effective, two or three passes must be made, which increases the cost of weeding. The best method to avoid weeds is mulch prevention. This method involves spreading layers of various materials on the ground. It can be an organic mulch, based on compost, bark mulch, flax or hemp flakes, or cocoa shells. Or a mineral mulch, based on slate petals, crushed shale or pumice. Spread in a linear layer of 5 to 7 cm thick, it creates a very effective weed cover.
What other advice would you give to an amateur gardener regarding weeding?
Never overdose and respect the dosage indicated on the packaging. Always respect the conditions of use. Wear work clothes when weeding. If there is product left in the sprayer, iron a second layer on the plants rather than throwing it down the sink or gutter. Have a sprayer reserved for weeding. If you are using a selective weedkiller, for lawn, for example, do not walk on the grass for half a day to avoid transporting weedkiller elsewhere by the sole of your shoes. And also, never weed with soapy water, which pollutes much more than any commercial chemical. To ask your specific questions: www.promojardin.com