That's usually when they can be divided. But to do this right, how many floral stems are there? If there are less than a dozen, I would not divide it. Your location, soil type, and exposure are useful pieces of information as well as an image of the fully flushed out plant.

These plants like cooler zones, but a Mediterranean 7a climate is ideal, a subtropical zone 7a like North Carolina, not so much. Cool nights are a must in hotter ends of the recommended zones for planting.

thanks! eastern Long Island (NY). coastal area. this bed is somewhat sandy soil and North East exposure that gets sun until about 12/1p- then shade.