How to use different green manures depends on how much space you have free, how long it will be free of edible crops, the time of year, and your rotation. And of course your soil type - try as many as you can and find what suits your soil and plot. I've tried several, which are **starred**.
You can use green manures
- to protect your soil over winter, and fertilise in spring;
- as a permanent bed, from which you harvest the green stuff - to dig in as manure, or use as mulches;
- or for short-term summer bare patches.
A soil protection cover for over the winter
Sow after a crop is lifted to protect the soil over winter, and give the benefits of the green manure in the spring.
- Sow in August
- Trefoil.
- **Clovers** - not a great success for me. I think they need a longer season.
- Sow in September
- **Fenugreek** - overwinters if it's not too hard a season; excellent if sown in August or mid-September.
- **Alfalfa** - excellent; can be sown to end of Sept.
- **Phacelia** - overwinters if it's not too hard a season; excellent; can be sown to end of Sept.
- Annual Rye Grass.
- Tares/Vetches.
- Sow in October
- **Field Beans** - I'm trying these this year.
- **Hungarian Grazing Rye** - sow late so it doesn't over develop!
A Permanent Bed
Nice idea if you have the space. You grow the plant and harvest the green material regularly (before it flowers or becomes woody), rather than digging the plant in. Cut the greenery - to add to the compost heap, lay in the bottom of a potato trench, or add as a fresh manure in another bed. Some possibilities
- **Comfrey and Nettles**.
- many of the clovers - Alsike Clover, Red Clover, White Clover.
- Alfalfa.
For a bed left bare during spring or summer
You have one? Well done - actually, with a bit of thought, I can see several opportunities on my plot, and realise I've missed most of them so far! Ah well, there's always next year.
- For a period of 1-2 months
- Mustard; can be sown March to September. It's a brassica (and hosts club-root) and does not fix nitrogen.
- **Fenugreek**; can be sown March to August. Young leaves edible - used as a spinach alternative in Indian cooking. Nitrogen Fixer.
- For a period of 2-3 months
- **Fenugreek**; Nitrogen Fixer.
- **Alfalfa**; sow April to July, and dig in come autumn; Nitrogen Fixer.
- Buckwheat; sow April to August, attracts hoverflies.
- Tares/Vetch; sow March to September, and dig in autumn or spring; Nitrogen Fixer.
- **Phacelia**; sow March to September, dig in before it flowers - but leave some to attract bees!
- For a longer period
- Agricultural Lupin; sow March to June, and dig in autumn, or cut back and dig in spring; Nitrogen Fixer.
- Alsike, **White and Red Clovers**; sow April to August, and dig in during autumn, or in spring; Nitrogen Fixer.
- Fodder Radish; sow August to September (and it's a Brassica, so watch your rotation.
- Annual Ryegrass; sow March to April, and dig in come autumn.