Kitchen Garden Forum

I know it's recommended to leave their roots in the soil to increase nitrogen, but does the same apply to the remainder of the plant? Is it better to dispose of the vines on the compost heap or chop them up and dig them back into the soil to rot down over winter? Am not sure whether it's just the little root nodules which contain the nitrogen.

You're much better putting the tops onto the compost heap. That way, they will ferment away on the compost heap much more rapidly and effectively than if dug in. All plant material decomposes to release nitrogen, but before it does it takes a little bit to get the process going. This is why it is always recommended to dig in green manures a few weeks before planting a crop, to skip this "nitrogen debt" phase. Better to get full return on your investment by composting, which is easier than trying the chop it all into dig-inable pieces. Let nature break it down for you, is my advice.

My runner bean plants are now slowly getting covered in a black rusty spotty thing. I have only left them because I have one last pick just finishing, so they will be gone probably at the weekend. Is it safe to put these vines onto the compost?

My compost bins are actually in a north facing corner of the garden and everything rots down very slowly as they never get any sun on them. . Last year I chopped up my bean vines and dug them into a trench in a sunny south facing border where I was going to grow my beans this year. By early spring they'd rotted down completely without a trace so I'm now inclined to compost my autumn debris in situ in this location to get a quicker result. The soil here often felt quite warm, even in winter on sunny days, which is why I was wondering about the nitrogen issue.