[al78]

I grew a green manure (Italian ryegrass) over winter on part of my plot and unfortunately due to the ridiculously wet winter was unable to dig it in until early March. I understand that you have to leave it for at least three weeks to rot down before sowing seeds in it. The problem is, despite digging it in it kept springing back to life, even covering it with black plastic hasn't helped much, so I have to keep going over it and chopping it up every weekend until it finally dies. This means that a large part of it won't be cultivatable until after Easter. The thing is, my soil is heavy clay which becomes sodden in the winter, so digging it in then is a no-no, but if I wait until it is dry enough to dig, then it is so close to cultivation time that I can't try sowing anything early under cloches (because the green manure won't have rotted down). How do I get around this problem of wishing to have a natural soil benefitting mulch over the winter period but having a soil type that can't be dug until it's almost time to start sowing?

[diospyros]

I don't know for sure, because I am feeling my way with this too, but I agree with you about having winter soil cover.  I don't like the sound of rye.  I'm going to try field beans and tares because they look easier to cut down.  At least the soil is covered and broken up by the roots over winter, even if the growth doesn't all get dug in.  It will get returned to the soil as compost eventually.  Also, thinking about what crop comes after the green manure e.g. robust things you plant out later in the season rather than tiny little seeds.  Come to that, beans and tares could be cut down and put in the bottom of a potato trench.

[Cake Lady]

It sounds like that's not one I'm going to try!  I've grown winter tares, fenugreek, mustard and field beans, all with no problems once dug in - but that doesn't help you now.

From what I understand, and other may say different, it's only seeds you can't plant for 3 weeks.  Something about the gases that are given off when the green manure decomposes that inhibits germination.  Small seedlings are fine, so depending on what you wanted to plant, you could germinate the seed another way - in modules or pots or even damp kitchen paper etc then transplant and the gases should not affect the plants.  I've never tried this though, so can't comment on how successful it'll be.

[Potty Plotty Lotty]

We've got a similar problem this year and resorted to putting the rye grass on the compost yesterday. Not ideal but I do find that the rye grass keeps the soil more friable than if it's uncovered over the winter so there is still some benefits, even if it's not bulking up the soil (in the short term at least).

We tried Hungarian rye grass when we first took on the plot and struggled with that so went to Italian a couple of years ago which is easier to dig in (if you catch it early enough).

For us the jury is still out as to the overall benefits (vs time involved) and I prefer a limited dig approach to the plot so it doesn't really fit in with this philosophy.

[al78]

I plan to try field beans for overwintering this year, however I haven't had much luck with getting leguminous green manures to grow on my plot. I had sown beans with the ryegrass but only the ryegrass grew. I also sowed an autumn/winter mix of mustard, clover and rye on an adjacent part of the plot, this time only the mustard grew. Unfortunately I didn't cut it down when it flowered, because I planned to let the frost kill it then it would lie on the ground over winter and gradually decompose. Unfortunately this doesn't work if you have a winter with virtually no hard frosts like the one just gone, the mustard just goes through its complete life cycle then gets blown down in the winter gales and eventually dies leaving woody stalks. I don't think I've quite got the hang of this green manuring thing. 

[ThePragmatist]

I have heard that clay soils benefit from being left uncovered to be broken up by frost. Not an alternative green manure but an alternative

[beesrus]

I didn't fancy the ryegrasses. Others told me they could be difficult to dig in, and some manures grow too woody if one isn't careful.
I've just used the Winter tares, which I sowed the end of September. It worked a treat, soil was protected, and fairly easy to cut a couple of times, and dig in. Perfect nitrogen fix for brassicas or sweet corn if a later crop is required, to give time for the soil to dry out for the dig over. Has hugely benefited the soil structure of those beds.
Apart from Winter coverings, some people use green manures in the growing season to improve the soil structure of heavy clays. Dobies for instance do a Spring and summer quick fix.

[Eightball]

I covered large parts of my plot last autumn/winter with grazing rye, winter tares and mustard. I'm on heavy clay soil and just made sure I dug them in pretty well so very little/none of the green was showing. Also hacked it to pieces with my spade as I was digging. It's a little bit labour intensive but the rye has a really deep network of roots which will help your clay soil in the long run in my opinion.

But as others have said you could try field beans instead of the rye as they would probably be easier to dig in.

Also you could try crimson clover, phacelia and mustard as a cold winter will kill them and then they can be left to rot down naturally. Having said that my phacelia I planted overwintered this year because it was so mild. Still much easier to cutdown/dig in + if left to flower it is very pretty.

[spuriousmonkey]

I haven't really been charmed by my rye grass experiment and I only did it on one square meter of area. I was a bit suspicious.

I like mustard. Even if you let it grow too long you can pull it out and just use it to cover an area for protection.

I also have the local finnish variety of broad beans. They are quite tiny. Very labour intensive if you want to eat them. I switched now to another broad bean variety and use the finnish ones as a green manure. Works quite well too. But they don't cover the soil much. So sometimes I add them to a mix of other green manures.

Mustard grows fast and covers an area well though.

I am not really convinced though by green manures yet. I think I am doing it wrong. But I like the fact that certain areas of my allotment are covered. Even if it is with someone only partially eatable. (i eat mustard leaves in salad when they are still young plants).

Has anyone got experience with clover as a green manure?

edit:

oops didn't read the posts properly. There is info on clover in the previous post.

[Salmo]

Any areas that you want to plant/sow early in the season should in my mind be dug rough in the Autumn and left to weather so that they make a good seedbed in the Spring.

Try growing your overwintered green manure where you will not be planting until later. Perhaps where you are going to grow sweetcorn, courgettes, brassicas, runner beans, french beans, leeks etc. That will mean that you are not in a hurry to dig and can wait until the soil is a bit drier. You then have plenty of time to tame any sticky out bits and break the soil down. If the crop gets a bit long cut it down and compost it. The roots of ryegrass are the valuable bit.

[Yorkie]

Don't forget that mustard is a member of the brassica family - worth bearing in mind for crop rotation or clubroot reasons.

[GrowinGrowinGone]

I can sympathise with what people are saying about this.  On my plot that has very heavy clay, I also put overwintering green manure in.  Everyone commented on how well it has grown, even some was jealous cos mine was doing so well while theirs had been pretty poor.  How pleased was I with myself....until I tried to dig it in.  I used crimson clover, hairy vetch, and rye grass.
It's been a nightmare trying to dig it in, I put it down to not having done much digging for a while and that I would soon be ok once I started getting stuck in.  In the end I gave up after a few days digging the raised beds over, covered them with cardboard and decided I will cut some holes in the cardboard, and plant that way.  I dont think I will be using green manure again.   

[al78]

Thanks for all the insights. I guess it is a case of trying different things to see what works best. I think next time I'll probably avoid sowing anything where I intend to plant early crops in the spring, as someone else suggested.

[Jackypam]

I think I'll cover the soil with manure. That doesn't tend to grow!