Choosing a green manure.

- Choosing the right Green Manure
Use the table on WEB when Choosing Green Manure Seeds to help work out which one will be best for you.

- Gardening Features - Timely Gardening Advice from Crocus.co.uk
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.

- Sow a patch and replenish your plot - Telegraph
...every year that I don’t plump for anything permanent, I can fill it with phacelia.

Green manures are one of the cornerstones of organic agriculture, essential to promoting a healthy soil, free of man-made fertilisers and encouraging a deep humus-rich topsoil.
There’s no reason why we shouldn’t enjoy their many benefits in the garden or allotment.
If you’ve an allotment, casting a few handfuls of Hungarian grazing rye over an empty end-of-season bed means that when you return, refreshed, after winter, the soil is in better heart than when you left it.
Yellow trefoil sown under tall plants like climbing beans is a beautiful way of covering the soil, attracting insects, retaining water and cutting down on weeding.

And if you’ve recently taken on an allotment and the initial enthusiasm has given way to a little trepidation, consider giving some of the space over to summer green manures.
This allows you to concentrate on making a success of a smaller area, while enriching the rest to expand into when your confidence is up.

How to grow
Green manures are fantastically easy to use: for most, it’s as simple as broadcasting them direct in as good a tilth as it’s practical for you to prepare, lightly raking over and leaving them undisturbed to germinate and grow.
Although some green manures will last for many months, most can be used as temporary space fillers, cut down and dug in after three months or so.

Some grow beautifully in combination.
I use a summer mix of phacelia, buckwheat and white clover to maximise the insect invasion while improving the nutrient status and structure of the soil.
Now is the perfect time to sow many of them.

Summer green manures
Phacelia Sow between March to September.
The flowers draw in beneficial insects. May last all winter in the south of the country.
Buckwheat Sow between April and August.
A deep-rooting green manure that grows happily on poor ground, improving it as it grows.
A fine insect attractor, too.
White clover Sow between April and August.
A low-growing nitrogen fixer with white flowers that attract insects.
Yellow trefoil Sow between April and August.
A low-growing nitrogen fixer with yellow flowers, perfect as an insect-attracting ground cover between tall plants – I undersow peas and beans with it to keep moisture in and weeds out.

Winter green manures
Although usually not as striking as their summer equivalents, the overwintering green manures are invaluable for protecting and enriching the soil during the harsher months.
Hungarian grazing rye Sow August-September.
Like a large, rough grass, this is the one for fast-growing, overwintering coverage, producing lots of green to be dug in in spring.
Crimson clover Sow between April and August.
A nitrogen fixer that grows taller than white clover, with elegant crimson flowers through the summer.
Alfalfa Sow between May and July.
Not the prettiest, but it makes up for it in hard work through the winter, drawing up minerals and nutrients from the subsoil – essential elements for healthy plant growth – while fixing nitrogen.
Red clover Sow between April and August, adding nitrogen to the soil and attracting beneficial insects.
Can last for two years or so, making it ideal should you need longer-lasting coverage.
Field beans Sow between September and November.
An excellent, fast-growing winter cover that also adds nitrogen to the soil.

Find where to buy:
- The finest range of Green Manure Seeds for all soil types.

- Amazon.co.uk: Green Manure - Summer Mix: Garden & Outdoors

My choice:
Yellow trefoil
Crimson Clover
Mustard
General Mix
Phacelia