Charcoal as an additive serves various purposes in the garden. It can be added to potting mixture or added directly to the ground.
- Its addition to soil makes a well-draining potting mix. The roots can breathe easily as it is porous and provides good circulation of air.
- Charcoal helps in increasing the soil pH. If the pH of the soil is 5.5 or less, it can be raised by adding charcoal in the ratio of about 100gm of charcoal t a 12-inch pot of soil. Adding more than that may increase the pH to more than 6.5, which can hamper the absorption of nutrients by roots.
- Charcoal absorbs nutrients and fertilisers that are given to plants and prevents them from leaching. These are slowly released into the soil as needed. Beneficial soil microbes also hold onto charcoal leading to an improvement in soil quality.
- Charcoal powder acts as an insecticide and can be sprinkled over plants. If a chemical insecticide is sprayed over a vegetable or fruit plant, a spray of a suspension of charcoal powder and water helps to neutralise its harmful effect.
- A soil mix for adenium and succulents having 10% charcoal helps in the prevention of fungal infections.
- It can be used for mulching as it helps retain moisture within the soil and prevents unwanted weed growth.
- Charcoal has a low density and is thus lightweight. Filling the bottom of the pot with charcoal instead of gravel and stones can reduce the overall weight of the pot. This is an important aspect of terrace gardening.
- Charcoal tends to absorb foul odors and can be added to compost bins and manure piles without compromising the quality of the products.