Tree peonies reach their full potential when planted in sunny locations. However, they can tolerate light shade and in hotter southern climates actually welcome some shade from intense midday sun. Soil should be rich, loose, well-drained and slightly alkaline with supplemental organic matter or humus added so they can develop deep roots. Avoid placing too near large trees to avoid tree root competition. If planting more than one tree peony, space at least 3 to 6 feet apart.
If your tree peony was received in a container, dig a hole 2 feet deep and 2 feet wide. Carefully remove the container and place plant so the top of the soil ball is level with the soil line. The graft of the tree peony will be well below the soil line. This allows the plant to eventually develop its own root system and no longer depend on the rootstock to which it is grafted. Water thoroughly after planting.
If the plant you received is bareroot (without soil around the roots), dig a hole large enough to accommodate the root system and deep enough so the graft is located about 4 inches below the soil line ( a little deeper in lighter soils). Put soil around the plant until hole is about 3/4 full, then add water to remove air pockets. Fill the remainder of the hole. Water thoroughly immediately after planting.
A 3 to 4 inch layer of organic mulch will aid in water retention during summer until plants are established. If fall planted, a winter mulch is beneficial for the first few seasons. Keep weeds removed around the plant. A slow-release fertilizer can be applied to the soil surface every three years, or if you prefer, give a light application of rose fertilizer in spring and again in summer. It’s best not to over-fertilize.
A tree peony should not be cut back to the ground in the fall like herbaceous peonies. They are woody plants that develop into small shrubs. If any pruning is necessary to control size or eliminate dead wood, do so in late winter or early spring. Once established, tree peonies are extremely hardy and tolerate heat and humidity. Very little maintenance is required.
Please be patient with your tree peony. It can take until at least the 3rd year before any blooms appear. In fact, it is beneficial to the plant if it doesn’t bloom the first couple years so the plant’s energy is invested in establishing its root system.Young tree peonies sometimes do not bloom true to form and need to be mature or fully established for the flowers to display their full glory. Once established, tree peonies have been known to grow in one place for 50 years or more, so they are a long-term investment.