Thanks fellas.
How much you cut them back really depends on the space you have available for overwintering. If you have ample space, don't cut them back at all and that's the way I did it the fist time I overwintered only a few, but mites and aphids were more of a problem. If you want to overwinter and only have a small area to spare or want to carry more plants over, whack them back to a stump and prune the roots to fit a smaller pot.
How much you cut them back really depends on the space you have available for overwintering. If you have ample space, don't cut them back at all and that's the way I did it the fist time I overwintered only a few, but mites and aphids were more of a problem. If you want to overwinter and only have a small area to spare or want to carry more plants over, whack them back to a stump and prune the roots to fit a smaller pot.