I have tons of Cannas in my back yard. They've been out there for over
a decade. I never dig them up, and they continue to multiply. On very
cold winters the leaves freeze a bit, so I cut them back down even with
the ground, and in a few weeks after the first warm weather (March or
so), they spring right back up.

I live in Sacramento.

Myrl Jeffcoat
http://www.myrljeffcoat.com