If I didn't remove the dried stalks from mine each fall, I'd have them coming up as thick as grass out there. I end up with a couple of grocery sacks stuffed full of dried stalks with hundreds of seeds that I scatter elsewhere or share with people who have an acreage. Mine are natives I got from Kansas, the whole roadside was solid pink for miles with them. Each spring I always have some volunteers from seeds that fell off when I cut them back.

I'm also in Zone 4 and they do reseed in the wild here, but not thickly. In my garden I don't think they have reseeded to any degree. So I'd maybe try both - don't deadhead and also get some new plants underway just to make sure.

I should add that I have sandy soil with gravel on top so most seeds have excellent conditions for germinating here, its great for direct sowing but I do have to take care and deadhead each fall.

This post was edited by TexasRanger10 on Mon, Aug 25, 14 at 15:40

They are natives here. We leave part of the back yard unmowed where they grow. It was heavenly last year to walk amongst a hundred of them.