Green Manure
If you want to save money, growing green manures can be as good for your bank account as the actual growing of your own food. By supplying nutrients and humus to the soil, green manures save you from having to purchase muck and fertiliser. And there's a further saving as you can also compost green manures and this will make your own potting compost.
Add to this the fact that you can always let some green manures run to seed, and your first purchase of green manure seed could be your last!
The idea is so simple. You sow green manures in soil that has become empty for the winter as the crops (and/or bedding plants) have finished. Green manures keep the soil in better condition, prevents weeds taking hold, and uses sunshine, soil moisture and nutrients that would otherwise go to waste.
Then, before the soil is needed the following year, the green manure is incorporated to improve the soil. It does this as it rots down (though this does take a while, so it'll be a month or two before you can sow). Also, green manures can be taken out, composted and returned to the soil later.
There is, however, one drawback to green manures that rarely gets written about. These are plants capable of germinating in late autumn and growing though the winter (coming mainly from agriculture). They include plants such as tares and vetches, Hungarian grazing rye and clovers.
These are very useful in agriculture, but rather hard to deal with in a garden situation as they're also vigorous perennial weeds. The clovers, for example, can be an excellent long term green manure but are not convenient for briefer terms as they're slow to grow and hard to eradicate once established.
Fortunately any green manure - even the most vigorous and persistent types - can be incorporated in situ by entirely covering the area where they are growing with black plastic. Kept in place for a month or two they exclude the light, and deter the plants from life-saving sunlight.
This may not always be convenient, or attractive, so I have found other plants that are easier and quicker to eradicate. For many people they will make more acceptable subjects for green manures. Try miner's lettuce (claltonia) and lamb's lettuce (valerianella) ; they make excellent weed-excluding ground cover, and are also good in salads. Poached egg plant is another superb ground covering plant rarely allowing any weeds to germinate. If left to flower it is also attractive to beneficial insects. But the greatest advantage to these three green manures is that they strip away neatly and easily, with no annoying re-growth after.
Add to this the fact that you can always let some green manures run to seed, and your first purchase of green manure seed could be your last!
The idea is so simple. You sow green manures in soil that has become empty for the winter as the crops (and/or bedding plants) have finished. Green manures keep the soil in better condition, prevents weeds taking hold, and uses sunshine, soil moisture and nutrients that would otherwise go to waste.
Then, before the soil is needed the following year, the green manure is incorporated to improve the soil. It does this as it rots down (though this does take a while, so it'll be a month or two before you can sow). Also, green manures can be taken out, composted and returned to the soil later.
There is, however, one drawback to green manures that rarely gets written about. These are plants capable of germinating in late autumn and growing though the winter (coming mainly from agriculture). They include plants such as tares and vetches, Hungarian grazing rye and clovers.
These are very useful in agriculture, but rather hard to deal with in a garden situation as they're also vigorous perennial weeds. The clovers, for example, can be an excellent long term green manure but are not convenient for briefer terms as they're slow to grow and hard to eradicate once established.
Fortunately any green manure - even the most vigorous and persistent types - can be incorporated in situ by entirely covering the area where they are growing with black plastic. Kept in place for a month or two they exclude the light, and deter the plants from life-saving sunlight.
This may not always be convenient, or attractive, so I have found other plants that are easier and quicker to eradicate. For many people they will make more acceptable subjects for green manures. Try miner's lettuce (claltonia) and lamb's lettuce (valerianella) ; they make excellent weed-excluding ground cover, and are also good in salads. Poached egg plant is another superb ground covering plant rarely allowing any weeds to germinate. If left to flower it is also attractive to beneficial insects. But the greatest advantage to these three green manures is that they strip away neatly and easily, with no annoying re-growth after.
Inter Cropping
Green manures don't have to be sown before or after your main crops, they can grow side by-side. This is called inter cropping or under sowing. It is particularly useful alongside taller growing crops such as sweet corn, and others that need a good spacing between them such as brassicas, as it covers soils and prevents weeds taking hold.
To avoid the green manure from competing with crops it is best to wait until the crop plants are actively growing before setting down the green manure seed.
Where brassicas are grown it is agood idea to sow legumes such as peas, beans and lupins as your crops will really benefit from the nitrogen that these green manures fix into the soil. I also heard that trefoil sown alongside brassicas helps to prevent cabbage white butterflies from devouring the crop, though I have not tried it.
Clover, radish and even lettuce (all types of green manure) make good under sowing options for most taller or spaced veg,
including sweet corn, but once again legumes also make good planting companions here.
To avoid the green manure from competing with crops it is best to wait until the crop plants are actively growing before setting down the green manure seed.
Where brassicas are grown it is agood idea to sow legumes such as peas, beans and lupins as your crops will really benefit from the nitrogen that these green manures fix into the soil. I also heard that trefoil sown alongside brassicas helps to prevent cabbage white butterflies from devouring the crop, though I have not tried it.
Clover, radish and even lettuce (all types of green manure) make good under sowing options for most taller or spaced veg,
including sweet corn, but once again legumes also make good planting companions here.
Plant
Buckwheat Crimson clover Fenugreek Lupin Mustard Phacelia Ryegrass Trefoil |
Nitrogen Fixing
No Yes No Yes No Yes No Yes |
Time in ground
3 Months 2-5 Months 2-3 Months 3 Months 1-2 Months 1-2 Months 7 Months 3-12 Months |
When to use
Early Spring to Early Summer Early Spring to Early Autumn Early Spring to Early Autumn Early to Late Spring Early Spring to Early Autumn Early Spring to Early Autumn Early to Mid-Autumn Early Spring to Early Autumn |
Sowing Rate
(per sq M) 28g 4g 4g 2 Inch / 5cm Apart 4g 4g 28g 4g |