Coneflowers - remove heads or leave to propogate?
I have a question about the best way to propogate coneflowers. I've planted several coneflower plants in the last two years (probably 15-20). I have a lot more space I could plant them in, so I'd love to be able to get more plants out of what I currently have. I've read a lot of postings saying that if you leave the dead flowers, they will tend to reseed themselves, or that you can pick the dead flowers off and remove the seeds yourself late in the year and then plant them wherever you want. I've also read that you should remove any dead flowers to encourage new blooms. So my question is, what is everyone's opinion if I want to be able to make my plants "multiply", whether by self-seeding, harvesting seeds, or by splitting the plants? Obviously leaving the dead flowers on and cutting them off are two very different approaches, and I'm curious as to what everyone else does.
Any help is greatly appreciated. Thanks!