Green manures are a vital ingredient for organic sustainable gardening. Green manure plants are fast growing annual crops. They often consist of a legume combined with a grass eg. mung bean, rye, oats, cow pea, lab lab etc. These crops are grown to both build organic matter, and to ‘fix’ nitrogen in the soil.
The green manure crops are grown to flowering, then they are are mowed down, the greenery is used as mulch and a soil amendment. I have a number of beds growing green manure at the moment, in preparation for my heavy feeding winter crops of broccoli, kale and garlic.