What are green manures?

Not actually manure, but fast-growing plants that are purposefully sown to spread over bare soil to provide a dense cover that both smothers weeds and helps to prevent soil erosion. You can sow in the late summer or autumn and leave to grow over the winter, the plants will absorb any remaining nutrients which would otherwise be washed away with the autumn and winter rains, they are then dug into the ground to return the valuable nutrients back to the soil.

Where can green manure be used?

Usually used for crops, green manures can work equally well in the garden especially if you have an area that you only plan to work on in the following spring. Once spring does arrive, dig the plants in to the ground and leave for at least two weeks before adding any plants or crops as the decaying greens can prevent new plant growth until they have broken down. A lot of green manures, especially in the legume families will develop nodules on their roots which will fix nitrogen levels in the soil.

What are the best seeds to use for green manure?

Try the following seeds:

  • Alfalfa (Medicago sativa)
  • Buckwheat (Fagopyrum esculentum)
  • Red clover (Trifolium pratense)
  • Fenugreek (Trigonella foenum-graecum)
  • Grazing rye (Secale cereale)
  • Broad beans (Vicia faba)
  • Italian ryegrass (Lolium multiflorum)
  • Mustard greens (Brassica juncea)
  • Phacelia
  • White clover (Trifolium repens)

You can purchase many different seed mixes and these are widely available in garden cnetres and from online stores.