Alfalfa is a very deep rooting green manure with vigorous roots that can draw up sub-surface minerals and break up soil pans. It is can overwinter once well established and will grow for a year or more.
It dislikes acid or wet soils but does well in dry conditions. It fixes nitrogen from the air in its root nodules and releases it once dug into the soil. It is a hardy annual that can be sown from April to July and can be grown for a few months or a year. If grown long term, Alfalfa should be cut down 2-3 times a year to encourage new growth, the cuttings can be composted or left on soil surface as a mulch. Alfalfa adds lovely organic matter to the soil but it should be dug in whilst plants are fresh and green as older woody growth does not decompose as readily Valuable nitrogen is lost trying to break down the tough stems.
It is part of the legume family and should be treated as such for crop rotation purposes. Sow before nitrogen hungry crops like brassicas.
Alfalfa is grown around the world as a forage crop for animals, but it also has homeopathic medicinal properties helping in the treatment of anaemia & diabetes. Alfalfa sprouting seeds are also used as a crunchy topping for salads but this green manure is not fit for human consumption.
