Mine get about 2-1/2' to 3' in diameter. I really enjoy all the late flower sprays they put up.

Oh good! I was hoping the upper range of what I was reading was correct. Steve, are yours in sun or shade?

Mine are in mostly shade. They would fry in the summer, in my dry soil, if they were in a sunny spot. I'm sure they would be fine in some sun if your soil is moist, though.

I’m late to the party here, I have several, in shade and in mostly sun. I have no burn, no supplemental water and they look great all season. In my experience here, anything that blooms late has great looking foliage all season. I do find volunteers seedlings every spring. Mine get to about 2’ in diameter, about 18” tall, the plants are always full.

Sherry

One of the best in a boatload of hyped up short-lived newish varieties. Doesn't fade out in a year, heat tolerant (mine are in partial shade emphasis on shade,) and the flowers are blooming now on Sept 26 and should be a presence for another two weeks. So easy to divide. Big hunks come apart so you are not replanting a division the size of your pinkie nail.

I'd guess at maturity they are 18" inches across, the flower stems are nearly 2" high. The leaves are big and bold and a presence.