This has been answered earlier

And the answer was......yes, let it die down and manure it if possible. If anyone tells you not to compost any of it don't listen. I've done it for years without a problem. They also say dig it up in the autumn and let it get frosted over the winter. Depends how much work you want. I've done it and there does not appear to be any difference between digging up and leaving.

That's right, and I found it doesn't grow so well after being disturbed.