I've seen this as possible, but when I transplanted mine (P. vulgaris) recently, there wasn't a "crown" to divide, just a taproot. These plants aren't young, either, though they were in sandy, sunny, non-fertile rock gardens.

So, does anyone have experience with takng root cuttings of these? I'd guess in the fall, but what part of the root; inside or overwintered, etc?

Any help would be great! Thanks.