Green Manures | Incredible Edible Todmorden | Blogs

Green Manures

Last update: 7.04.14 First posted: 7.04.14 by in

Green manures are plants that are grown not to eat or for their beauty, but for the health of the soil. Growing ‘green manure’ is an effective way to improve your soil. They help in several ways. As they grow the foliage helps to suppress weeds and also provides cover for beetles and other pest eating creatures. They protect the soil from heavy winter rains which can wash nutrients away and harm the soil structure. The roots also help improve soil structure and some which grow deep bring trace elements to the surface. Those of them which are nitrogen fixers absorb nitrogen from the air and then, when the plants are dug back into the soil they release the nitrogen and other nutrients for whatever you plant next to use.

Grow them wherever the ground would be unused for six weeks or more, many can be left in place for a year or more and cut back to provide a mulch. People who grow to strict organic standards prefer green manures to animal manures such as horse manure as they worry that horses may have been treated with antibiotics. Seeds can be obtained from organic suppliers such as Garden Organic at Ryton, mixtures are sometimes available in large garden centres.

Green manure plants Overwinter Nitrogen fixer Sow
Alfalfa yes yes April-July
Field beans yes yes Sept.-Nov.
Buckwheat no no April-Aug.
Clover, crimson no yes April-Sept.
Clover, others yes yes April-August
Fenugreek no no March-Aug.
Lupins no yes March-June
Mustard no no March-Sept.
Phacelia yes no March-Sept.
Radish no no August-Sept.
Rye – grazing yes no August-Sept.
Rye- grass yes no Spring or Autumn
Tares yes yes March-Sept.
Trefoil yes yes March-August

For soil improvement it is better to dig green manures in before they flower, however some of them have lovely flowers that are attractive to bees and other beneficial insects. Try leaving some patches to flower.

Caution: As green manures decay in the soil some of them release compounds that inhibit the germination of small seeds. To avoid difficulty follow them with transplanted crops, sets or tubers or allow at least four weeks in between digging in green manures and sowing seeds.

For further information contact Garden Organic, Ryton.

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