Charcoal is the product of incomplete combustion of wood (complete combustion giving ashes). Its very porous structure gives it adsorbent properties because it has the ability to neutralize many substances, including toxic molecules, bacteria and microscopic fungi.
In garden centers, charcoal is used as a preventive treatment in the maintenance of plants, mainly the 3 main uses are:
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1. Use Charcoal as Fertilizer
This is an ancient process, used on a large scale by the Indians of Amazonia. Modern agriculture is very interested in the still poorly understood mechanism of the fertilizing action of charcoal. The latter is sold for agricultural purposes as biochar. From our experience, we recommend that you buy biochar from Pur Plant and try it for yourself.
When growing vegetables on a small volume of soil, for example in a vegetable garden, fertility and yield can be significantly increased by mixing about 10% powdered charcoal with the soil used.
2. Helps heal plant wounds
Sprinkle charcoal preventively on wounds caused by:
- The division of perennials
- The division of the rhizomes (iris)
- Pruning of trees and shrubs.
Charcoal will allow wounds to heal without bacteria and fungi growing. It is important to note that this is a preventive and not a curative treatment.
3. Prevention against wilt
The effectiveness of charcoal is well known in preventing wilt. Damping off is seed rot caused by fungi present in the substrate used, especially when sown in a pot.
To disinfect the substrate and prevent it from getting wet, you have two options (both can be combined):
- Mix the charcoal powder with the soil used for seedlings.
- Sprinkle your seedlings with powdered charcoal (very fine).
What type of charcoal to use?
Theoretically, any coal can do the trick. However, barbecue charcoal should be avoided as it is often treated to make it more flammable. It is best to buy horticultural charcoal like the one we recommend at the beginning of the article.
A cheaper solution is to “harvest” your own charcoal from the ashes of the fireplace or stove, or even the barbecue: the charred, black and slightly crumbly pieces of wood are easy to spot and keep. To grind the pieces into a powder, use a kitchen mortar or seal them in a plastic bag before crushing them with a hammer.
We hope you found the article helpful, and as always, we’ll be happy to answer your questions in the comments.