Photo: tree peony at Staten Island Botanical Gardens
Itoh or Intersectional Hybrid Peonies (Paeonia spp.) represent a huge breakthrough in tissue culture propagation. Inherited from the tree peony is attractive dissected foliage. They are extremely winter hardy like the herbaceous types.
Plants grow two to three feet tall and wide. Strong sturdy stems support the huge flowers which size up to 10" across. Flowers are single, semi-double or double, and available in a wide range of colors including yellow. Flowers stand upright even in heavy rain and require no staking. Bloom time is longer due to additional flowers being produced on side shoots.
Peonies are long-lived, growing in the same location for decades. They need to be properly nourished annually. Peonies prefer full to part sun (minimum of 6 hours per day), average moisture and well-drained soil which is enriched with compost or mulch annually.
Bare-root peonies should only be planted in the fall as this coincides with the time that their tubers develop most of their feeder roots. Container-grown peonies can be planted at any time. Itoh hybrids demonstrate good resistance to peony blight (Botrytis paeoniae).
Proper planting depth is very important for peonies. The crown should be planted 1½ - 2 inches below soil level. If the eyes have already begun to grow, the new growth may be set slightly above the surface.
Itoh peonies are now available through e-commerce nurseries.