I regard them as a tender perennial. You'll need to lift the tuberous roots and store them frost free to grow them next year. You could also save seed - I seem to remember they germinate pretty easily.

They germinate REAL easy. If next year you have a thousand little plants in the same area, they will probably survive in the ground. The roots can get enormous. But they provide a great place for my cats to sleep during the day.

THANKS VERY MUCH, CATS NOT ALLOWED IN OUR GARDEN, BASIL KEEPS THEM AT BAY.

Just one point Drakey, please could you turn off caps lock? Otherwise it comes over as if you're shouting at us. Thanks a lot.