Cutting the stalks off doesn't affect the way it regrows...BUT in the spring, if there's a "wild" stalk, you can cut that back and a new one will grow from the base from another spot. I suppose you could make a less lopsided shape that way.
Barb

I cut mine back and they seem to do very well each year. People walk by and stop to admire them. Actually one guy came back and cut one to take home!

If you cut them back in the fall, I suggest you cover the stumps. The stems are hollow and will collect wintre rain. If you get a hard freeze the water in the stems may freeze and kill the root crown. I use a black plastic pot filled with chopped leaves. About 3 weeks before last frost, I remove the pot and leaves and let the sun shine on the stumps.

Do you have to cut them back to the ground each year? Is that to get more blooms?