Kitchen Garden Forum

On average, if you dig in green manure now that was planted in the autumn, how long will it take to break down?

Would you be happy immediately planting potatoes in recently dug in green manure?

Do I understand correctly that green manure functions purely as a soil conditioner and doesn't actually feed the soil? I'm talking about mainly grass-based green manures, here.

I find that grazing rye or Italian rye grass used as green manure takes about 4 weeks to start to break down and it usually needs another 2-3 weeks to "knock back" the roots which are fairly bulky. And on your second question, potatoes could probably cope with fairly recently dug-in green manure though I would certainly add some fertiliser. Small seeds would struggle.

Last months magazine talked about "lazy beds" which is turf turned over, with soil on top, ideal for tatties, so I'm sure you'd be all right with green manure(never actually used it my self though)

It's a first for me too. But with a brand new allotment site composed of heavy clay SOMETHING needs adding to the soil to make it move workable and the thought of leaving it bare over the winter did not appeal. The green manaure, which I think is mostly vetches and rye grass, looks really good: vibrant green!! Just started digging it in today.

I think it's good for root crops like potatoes, but grass type green manure needs to break down for longer than clover, lucerne or phacelia etc as it produces germination inhibitors which would be a problem with seed sowing. It is only temporary though and they will all help lighten up a clay soil or bulk up a sandy or poor soil.

I tried grazing rye for two seasons and whilst it did rot down it took so long that I ended up raking the courser bits up and putting them in the compost heap, I'll try something else next time.

I usually chop up green manure with shears before digging it in. I find this speeds up the rotting down process quite a lot.
I reckon on planting about a week after I've dug it in.
Previously,when I hadn't chopped it up it seemed to take ages to incorporate & rot down.

Richard - I like your new signature!

Westi wrote:Richard - I like your new signature!

I'm not the man I used to be just two years ago Westi, even-so, I have never been calm and dignified though I never get drunk.

Yes, I did chop my grazing rye but it's the course roots that remained and though they did eventually start rotting they were a nuisance amongst my planting. I used comfrey leaves as a mulch in that bed, strawberry bed. Those comfrey leaves rot quickly and they almost killed my strawberry plants. I didn't expect that to happen even though I have killed stuff with comfrey tea that was too strong. I need to re-think how I use the produce of my comfrey plantation, yes, it's a very useful and comprehensive nutrient source. But very strong.