Despite being zone 5, I've been able to successfully overwinter a couple of my blue ensigns in the ground using piles of leaves and a tarp. I've been giving one of them a hard cutback in June(perhaps 3 ft cut down by half) because it really takes off in May and I don't want it to outgrow its garden spot. Later in the season it is a large, dense, bloom-covered beauty. I could probably cut it back a bit earlier so it blooms a bit sooner.
