I was just looking at mine this evening, it's been moderately vigorous and now about 7 ft tall and has just one little sucker about six inches from the mother. It's planted on the southwest edge of a woodland setting that at times becomes hot and dry. The soil is loose and friable, though maybe a bit on lean side and my climate is also zone 4 a. These might possibly spread themselves around more in richer moister soils. The thing has never experienced any winter damage.