[JayG]

A few years ago I cut down my runner beans at about this time of year and just left the bines where they were (must have been short of compost space at the time)

Clearing the partially-composted remains away the following April I was suprised to find that the buried roots were sprouting away vigorously (several shoots per root), and wondered whether I could grow them on for that year's crop. Didn't actually do that as I wanted to grow them somewhere else on the plot, but now I am using a fixed Munty frame the possibility presents itself again.

I know that runners are perennial in warmer climates than ours; has anyone in the UK actually tried keeping them alive in winter to crop for a second (or more) year/s?

[Goosegirl]

No- I haven't. I suppose it will depend on the winter climate to get them through until the next year but if they do, then you won't be able to follow a crop rotation plan as I don't know if they would transplant successfully. Having said that, you could always leave one in its former place to see if it is successful.

[Spana]

, you could always leave one in its former place to see if it is successful.

Thats just what I did.  Left the roots in over winter and in the spring when having a tidy I left the last root in the row to see what would happen.  It grow and cropped the same as the new seed sown that year.

[Salmo]

They store carbohydrates in the thickened root. You are supposed to be able to lift them and store them like you can geraniums. I do not know anyone who has actually done it. If you leave them in the ground I imagine they shoot too early and get frosted so you would need protect them in a greenhouse until after frosts.

[GrannieAnnie]

But runner beans don't have to be rotated.  There are people on here and I know some people who keep their runner beans growing in the same place every year.

[JayG]

Hmmm, thanks folks. I think it was the covering layer of dead material that protected the roots from frost over winter so that they were still viable next spring. I agree with GrannieAnnie that runner beans don't usually need to be rotated, although if the roots are left in the ground it would be difficult to renew the organic material they like to grow in.

Maybe either lifting and storing the roots in a frost-free place before replanting or digging out and replanting in a newly-enriched trench in late spring would be the way to go. Has anyone successfully lifted and stored?

[Salmo]

They store sugars/carbohydrates in the swollen root. You are supposed to be able to store them over winter the same as you can geranium (pelagoniums) plants. i.e. keep dry all winter and water them to start new growth in the Spring. I do not know anyone who has.

One of the problems will be that they will want to start growing again before the frosts are over so they will need to be in a frost free greenhouse/polytunnel until frosts are over.

They may keep in the ground if well mulched but the problem will be protecting new growth from frost in the Spring.

[JayG]

Found this advice on Facebook of all places if anyone wants to give it a go:

Unless they're growing in a very sheltered site in free draining soil, dig up the tuber before the first frosts. Then just as for dahlias, leave to air dry for a week or so and store indoors over winter in slightly damp leafmould or the like. They'll grow again happily in the spring once potted up, but need a warmish greenhouse, conservatory, front porch, or larger than average windowsill.

This technique isn't used that often, but most useful for producing an earlier crop than outdoor counterparts grown from seed.

Got to be worth a try on at least part of the plot although I'm not sure about the potting up indoors bit...........?