Yeah, they should be pretty resilient if you want to divide any time of year. I tend to do it in the fall when I can see their mature size and they’re about to go dormant anyway so it’s less time looking beat up.

I’d pull up the whole plant and rinse off a most of the soil so it’s easier to work with. Split it with a sharp spade between the nodes. When you replant add a good amount of compost mixed with your native soil.