I don't know if they need to be divided, but I have divided mine in early spring & late fall & worked well both times, with no loss of bloom that I could tell. I have had mine several years & never thought to divide them. I couldn't tell that there was any loss of flower after at least 5 years, & they didn't multiply tremendously, but after i divided them, by the following year you couldn't tell I had divided. It seemed to encourage them into multiplying :) I certainly wasn't gentle. This spring when it was just coming up, I dug up a clump & pulled apart the best I could, more cutting it apart than anything.

Abi, if they like where they are, they multiply as a rabbits.
You could move or divide them practically all times of the season, except the time when they flower.
Actually you could do that even in that time, but you have to be very carefull not to broke stems. All other time they are not more sensitive to movement or divisions than hosta.

Thanks George and NGraham,
that would explain why only some of the bulbs are multiplying. I've had some growing on a slope for for few years and they've never multiplied. The half dozen I planted in a perennial border is now more like 2 dozen! I might divide in the fall as the border is getting quite crowded. /Abi

I never grew liatris before but bought some thru a catalog.
Can you start them indoors?

As a general rule (there's always exceptions) divide a plant furthest away from its bloom time. So I would divide liatris in spring.
Sally

Roxann,
Liatris is tough and very hardy. You can plant them outdoors now.

I have a liatris plant that has broken into chunks at the base. Are these chunks corms? If I plant them now (November) will they grow into new plants? How deep do I plant the chunks? Thanks for your help.