Green manures are plants that are grown to improve the soil, usually in organic gardens. Where there is new ground to bring into cultivation, or where soil is to be left bare for more than a few weeks, green manures are well worth considering. Green manures can suppress weed growth, prevent nutrient loss and soil erosion, improve the soil structure and add fertility to the soil.
- Choose your green manure. There are a number of plants that can be used as green manures - they are all annuals, grown from seed. You need to choose a green manure that is right one for your situation - taking into account your soil and climate, the time of year, the length of time the green manure has to grow and the improvement you are trying to achieve.
- Sow your seeds. Many green manure seeds are small, and can be broadcast sown onto soil that has been raked level. The seed packet will explain how much seed to sow. Others have large seeds that can be individually sown in neat rows. In dry weather, you may need to keep the seed bed moist until the plants have established.
- Concentrate your efforts elsewhere. The point of green manures is that they are left to grow, undisturbed, until the soil is needed again or until they have done the job they were sown to do. In the meantime, concentrate your garden effort in other areas.
- Dig in. When you need the ground, or before the green manures flower, dig them into the soil. The plants are then left to rot down and will add their nutrients back into the soil. If the top growth is tough, cut it down and leave it to wilt before digging it in.
- Or don't dig. In a 'no dig' garden, you can still use green manures. Simply cut them down and allow them to sit on the surface as a mulch, or remove the top growth to the compost bin and use its fertility that way. If the green manure continues to grow, cover it with a light-excluding mulch.
- Reap the benefits. The next crop of plants will reap the benefits the green manure has brought - weed-free, healthy and fertile soil, achieved without the use of harmful chemical products.