They produce larger flowers than regular tree peonies. Both hybrid and regular tree peonies have a serious fault. The stems are weak at the top. Tree peonies grow either from seed or from grafts. When grown from seed, they take at least 6 years to bloom.
Plants grown from grafted tubers usually bloom the third year after planting.
Because grafting is difficult, the average gardener should buy tubers that already have grafts on them. Tubers without eyes, or with only one or two eyes, often rot in the ground. And tubers with more than five eyes often fail to produce large flowers. Tubers are sold in late summer and fall. Some dealers sell fully grown peonies in the spring, but these plants are expensive and few of them live through the dry weather of summer.