You'll get more branching and more flowers if you pinch them. I aim for 4 sets of true leaves, always miss some, and do some early because I'm too busy to wait. It doesn't seem to make an earth-shattering difference to the average grower, but if you don't pinch you'll get leggier plants and fewer blooms.

Thanks so much. I'll pinch my Karmas at 4 sets of leaves. I certainly want to get the most out of this Dahlia season.

Great advice, Poochella. I would have said exactly that.