Choosing a green manure
You have plenty of choice; which green manure 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. For most people, a green manure that can be sown in late summer or early autumn and left to grow over the winter would be best. Clovers or rye grasses are perfect for this and will have time to grow before digging in during early spring a few weeks before planting.
On heavy soils, digging during early spring is not a good idea because you will damage the soil structure as you work. In this case, a tender quick-growing crop, such as buckwheat or fenugreek, would be a better bet because it will put on growth if sown straight after the last crop is harvested in late summer to be killed by the first heavy frost of winter and incorporated during normal autumn cultivation.
If you have a new garden or a barren plot that you don't intend to cultivate or plant for at least a year, then one of the longer-term green manure crops, such as alfalfa or alsike clover are worth sowing. If you find that you are ready to tackle the area earlier than expected, these green manures can be dug in at any time. Just leave a few weeks for them to rot down before planting.
Which green manure?
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 |
anytime 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 or late summer |
2-6 months |
any time before flowering |
You have plenty of choice; which green manure 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. For most people, a green manure that can be sown in late summer or early autumn and left to grow over the winter would be best. Clovers or rye grasses are perfect for this and will have time to grow before digging in during early spring a few weeks before planting.