Green Manure
Green manures are short-term crops that are specifically grown to be
dug back into the soil, adding organic matter and nutrients. The
main advantages of growing green manures are:
 •
To help break-up heavy soils
• Improve drainage
• To suppress weeds
• To add organic matter
to the soil to improve its structure and fertility
• To help make nutrients
available to plants that are grown in the soil afterwards
• To prevent nutrients
being washed through the soil in winter
• To protect the soil
from compaction caused by heavy rains
Green manures can be
either broadcast sown (thrown randomly) or sown in rows.
Prepare the ground as you
would for any other crop. Just as soon as a green manure has put on
some growth it is worth digging in. However, the longer you leave it
the greater the benefits.
Most green manures should
be dug in before they flower and set seed or before the stems go
woody. Dig the green manure into the top 6ins of soil. This is where
it will decompose most quickly. Cut the green manure a few hours
before digging so that the top growth wilts. Use a sharp spade,
shears, nylon-line trimmer or even a rotary mower to chop down the
green manure, and then incorporate everything (including the roots)
into the soil as you dig.
Leave three weeks after
digging in a green manure before planting or sowing the same ground.
The main drawback with
green manures is that nothing else can be grown in that area whilst
it is growing so it is best to choose an attractive, useful plant
such as Lupins.
There is a range of good
green manure crops; which 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.
|
Common Name |
Latin Name |
When to Sow |
Growing Time (months) |
When to Dig In |
|
Alfalfa |
Medicago sativa |
Late Spring |
3-24 |
While Fresh |
|
Buckwheat |
Fagopyrum esculentum |
Spring to Late Summer |
2-3 |
Before Flowering |
|
Alsike clover |
Trifolium hybridum |
Spring to Summer |
2-24 |
While Fresh |
|
Crimson clover |
Trifolium
incarnatum |
Spring to Summer |
2-6 |
Before Flowering |
|
Essex red clover
|
Trifolium
pratense |
Spring to Summer |
2-24 |
While Fresh |
|
Fenugreek |
Trigonella
foenum graecum |
Spring to Summer |
2-24 |
After Flowering before
pods develop |
|
Fava
beans |
Vicia
faba |
Autumn |
4 |
Before Flowering |
|
Italian ryegrass |
Lolium
multiflorum |
Early Spring |
2-3 |
Before Flowering |
|
Lupin |
Lupinus
angustifolius |
Spring to Early Summer |
2-3 |
Before Flowering |
|
Mustard |
Sinapis alba |
Spring to Early Autumn |
Up to 2 |
Before Flowering |
|
Phacelia |
Phacelia tanacetifolia |
Spring to Early Autumn |
2-6 |
Before Flowering |
|
Rye |
Secale cereale |
Late Summer to Autumn |
4-6 |
Before Flowering |
|
Trefoil |
Medicago lupulina |
Spring to Summer |
12 |
While Fresh |
|
Winter tare |
Vicia sativa |
Spring to Late Summer |
2-6 |
Before Flowering |
Now the difficult bit,
how to look after your garden.
|
