Got some of these today but, of course, no mention of the variety.

http://i34.tinypic.com/42vjo.jpg

The label says they grow to 18"-24" but, as they're in flower now at a
height of about 9", do I assume they'll flower again or what? It also
says they last one season, but I thought spray chrysanths were
perennial. Maybe they'll revert to something else next year.

Assuming they survive in some form, when should I think about dividing
or propagating them? I don't have a good record in this area, having
somehow managed to kill most of last year's.

Thanks for any advice