Green manures are short-term crops that are specifically grown to be dug back into the soil, adding organic matter and nutrients. The main reasons for growing green manures are:
- To help break-up heavy soils and improve drainage>
- To suppress weeds
- To add organic matter to the soil to improve its structure and fertility
- To help make nutrients available to plants that are grown in the soil afterwards
- To prevent nutrients being washed through the soil in winter
- To protect the soil from compaction caused by heavy rains
Here’s how to produce green manure:
- Sow either by broadcasting (thrown randomly) or sown in rows
- Prepare the ground as you would for any other crop
- The crop can be dug into the soil as soon as it has put on some growth but the longer you leave it the greater the benefits. However, it must be dug in before it flowers and set seed or before the stems go woody
- Use a sharp spade, shears, nylon-line trimmer or even a rotary mower to chop down the green manure, and then incorporate everything (including the roots) into the soil as you dig
- Leave three weeks after digging in a green manure before planting or sowing in the same ground
The main drawback with green manures is that nothing else can be grown in that area whilst it is growing so it is best to choose an attractive, useful plant such as Lupins.
There is a range of good green manure crops; which you choose will depend on when you intend to sow it and how long you are prepared to leave it growing before incorporating it into your soil. Here are some examples:
Common Name | Latin Name | When to Sow | Growing Time | When to Dig In |
Alfalfa | Medicago sativa | Late Spring | 3-24 Months | Any Time while Fresh |
Buckwheat | Fagopyrum esculentum | Spring to Late Summer | 2-3 Months | Any Time before Flowering |
Alsike clover | Trifolium hybridum | Spring to Summer | 2-24 Months | Any Time while Fresh |
Crimson clover | Trifolium incarnatum | Spring to Summer | 2-6 Months | Just before Flowering |
Essex red clover | Trifolium pratense | Spring to Summer | 2-24 Months | Any Time while Fresh |
Fenugreek | Trigonella foenum graecum | Spring to Summer | 2-24 Months | After Flowering before pods develop |
Fava beans | Vicia faba | Autumn | 4 Months | Any Time before Flowering |
Italian ryegrass | Lolium multiflorum | Early Spring | 2-3 Months | Any Time before Flowering |
Lupin | Lupinus angustifolius | Spring to Early Summer | 2-3 Months | Just before Flowering |
Mustard | Sinapis alba | Spring to Early Autumn | Up to 2 Months | Any Time before Flowering |
Phacelia | Phacelia tanacetifolia | Spring to Early Autumn | 2-6 Months | Just before Flowering |
Rye | Secale cereale | Late Summer to Autumn | 4-6 Months | Just before Flowering |
Trefoil | Medicago lupulina | Spring to Summer | 12 Months | Any Time while Fresh |
Winter tare | Vicia sativa | Spring to Late Summer | 2-6 Months | Any Time before Flowering |
Buy Green Manure seeds from Suttons:
- Green Manure Mix Seeds – adds nutrients and moisture to soil. Price: £2.99
- Organic Green Manure Red Clover Seeds – helps improve fertility. Price: £2.45
- Organic Green Manure Phacelia Balo Seeds – dense, quick-growing foliage. Price: £2.45