Sue Says
This is quite common with tree peonies because it does take them some time to settle in after planting. Its worth checking the area that you planted them in to ensure they are growing in optimal conditions. Peonies are at their best in sunny positions and wont do well in heavy shade. They also need shelter from cold drying winds and strong early morning sunlight. Check the soil isnt too wet as the plant will struggle and eventually rot peonies like moist soil, but it must be well drained. Check that the tree peony is planted so that the grafted union sits at least 10cm (4) below the soil surface. Shallow planting may hinder establishment and is often the cause of delayed flowering. Take care not to over feed tree peonies. If the soil is reasonably fertile then a high potash feed in spring, and a mulch of well rotted manure or garden compost in autumn will probably be sufficient. If everything looks as it should, then it may just require more time. These plants are better off if planted in the ground and are not the best candidates for container culture. Tree peonies are extremely long lived. Tree peonies are not ericaceous plants. In fact they prefer a neutral soil, therefore ericaceous soil is not necessary. Just plant them out in rich fertile garden soil and leave them to put down their roots.