Blooming reliably every spring, peony blossoms (Paeonia officinalis) are one of the showiest perennial flowers and are considered the backbone of the perennial flower border in temperate climates. They produce a dozen or more huge blossoms per plant, and a single bouquet will perfume an entire house. Peonies are one of the most care-free perennial flowers and also one of the most reliable. Barring a very late season frost that kills the already-formed flower buds, peonies will bloom every spring like clockwork, as long as they remain in full sun.
Although they grow to the size of a small bush, peonies are considered a herbaceous perennial because they die down to their roots in autumn and re-grow from them the following spring. Long-lived, it is not unusual for a peony to grow and bloom for more than 50 years in the same location, without ever being dug up and divided, unlike most varieties of perennial flowers. The single or double flowers are massive---up to 8 inches across---and bloom profusely in mid- to late-spring. Not even the rose can match the peony for the sweetness of its fragrance.
Choose a spot in full sun with rich, well-drained soil. Add a couple shovels full each of peat moss and compost, and a tablespoon of granular fertilizer to the planting hole. Consider the maturity of trees near the site; plant peonies in a location that will remain in full sun for decades to come, since peonies dislike being disturbed. One reason that mature peony plants stop blooming is that a tree has matured and encroached upon the peony's exposure to direct sunlight.
Although dozens of named varieties exist, peony flowers are either white, pink or deep rose-red, with single or double petals. The flowers last only a few days---less if pummeled by heavy rains---but if you plant early-, mid-, and late-maturing varieties, you can extend your peony-blooming season to several weeks. All varieties are fragrant, although some are much more fragrant than others.
Care and Culture
The single biggest reason for peonies to fail to bloom is that their roots were planted too deeply. They should be planted just below the surface of the soil, with the pink "eyes" poking through the surface. Other than that, cut off the dead foliage at ground level after it freezes in autumn and encircle the plant with a supporting fence when it has grown a few inches high in spring. This will support the stems so they don't fall over with the weight of the large, spectacular flowers.
Pests and Diseases
Generally not susceptible to pests, peonies are sometimes affected by fungal diseases such as botrytis blight and leaf blotch. To control, remove affected plant material and clean up all dead plant debris in autumn. The following spring, spray shoots as they emerge with a fungicide specified for treatment of these fungal diseases, following the manufacturer's instructions. The only insect that bothers peonies is scale, the hard-bodied insects that attach themselves to plant tissue. To control them, remove dead plant residue after frost in autumn and spray the plant the following spring in late May and also in mid-June. Use an insecticide specially formulated for the treatment of scale. Contrary to popular belief, the large number of ants that frequent peony blossoms cause no damage to the plant.