It depends on how large you want it to be. I've experimented with several, cutting to the ground or leaving unpruned. If left unpruned they developed a mounded shape with the branches drooping down after a few years. If pruned they maintain that 'starburst' shape. It really depends on how you're using the shrub. If in perennial bed, the smaller starburst may be a better shape.

Cynthia, I do like the "starburst" shape better. The tag on the plant says "height to 3 feet, spacing 4 feet" which, as I found out when I arrived home with it and did some research, is WAY smaller than it actually gets. I put it in a small moonlight garden as a background plant but I am afraid that I may have to move the whole thing because it may outgrow it's spacing.

To keep it in check this year I should just cut it back even further? When you say "cut to the ground" do you mean all the way down? Thanks for your answers!