I have been having trouble with mine in the ground, for the last few years its being stripped no matter what I did from gravel to copper rings, you name it i did it, so just as the first shoots appeared a few weeks back, I dug two thirds of it up and potted it.
Fabuolus, the bit that I left in the ground has been completely stripped and so far the potted on portion is blooming, well done me ;D