I bought a cheerful hollyhock last year at a local nursery because I was told it was a hardy perennial that needed little care other than water. But I just read in a gardening book that it is an annual, unless allowed to "self-seed". When exactly does it do that? I may have loped off its head once the flower died and the stalk turned brown...I thought that's what you're supposed to do...I really am new to gardening!!! Will it grow back?