I have had String Theory about 8 years, have not divided it yet to note its growth habit. Don't really remember anything unusual from when I planted it, but that is not surprising
. It has not grown very fast, but I do have a good clump of it now. I like the blooms, it's bud count is more like 15 on a good year, and I don't think it has ever rebloomed. I don't think it reaches 38" tall either, more like 32-34". Not short at least, so that is fine with me.