September - the harbinger of fall. The chores start to add up while the days get shorter and cooler.
It is time to start cleaning out landscapes and cutting back fading summer plants. It is also the time to give your peonies some attention. Labor Day is the signal that it is time to cut back peonies for the year. Did you know the peony is one of the few perennials that actually prefer to be transplanted and divided in the fall? Not to be confused with daylilies and hostas that perform better when transplanted in the spring, transplanting peonies just after Labor Day is usually the ideal time to complete this task.
There are several reasons for dividing and transplanting peonies. Peonies prefer a good amount of sun, but can tolerate some shade. If the peony’s location is heavily shaded by a tree or large shrub, the flowering can be reduced. Transplanting the peony to a spot with more sunlight will increase flowering. Another reason to transplant and divide peonies is overcrowding. Sometimes older, more established peonies can become overcrowded and as a result will produce fewer flowers. Dividing the peony will refresh and invigorate the plant.
After the stems have been cut to near ground level, begin digging around the plant. It is best to dig straight down, about 6 inches from the plant using a sharp spade or shovel. If you are transplanting the entire plant, make a few passes around it, digging deeper with each pass (to about 14 inches) and at more of an angle. If you are dividing the plant, determine how much of the plant is to be removed and dig through the plant, segmenting the portion to be divided.
Now you are ready to begin prying the plant upward. It is normal hearthe snapping of the roots at this point. After all roots have been cut or snapped off, the plant can be lifted out of the hole with a shovel and carefully turned over so that it rests on its stems
Carefully loosen and remove as much soil as possible by either rinsing with water or using a sharp stick or screwdriver. If you have an assistant like Tobias, the paws come in handy for this step! Once soil has been removed, the plant can be cut and divided into sections with at least 5 “eyes” each. The eyes are the small pink nodes along the roots that are the stem buds for the next season’s growth.
Each section is now ready to be planted. Dig a hole that is slightly larger than the root mass to be planted. (This is another task that Tobias is quite helpful with!) At the end of this step, the eyes should be planted at a depth of just 1-2 inches below soil level. If they are planted too deep they will fail to bloom for a few years. Peonies prefer well drained soil that is rich in organic matter. Adding peat moss or compost to the soil that is removed during this step is a good idea, but is not required. Place the root mass in the hole and begin to backfill the soil. Once the eyes are covered with soil, add a 1-2 inch layer of mulch to protect the plant from extreme freezing and thawing through the winter. In the spring the mulch can be removed after the threat of a hard freeze has passed.
Even if the peony is planted at the correct depth, poor flowering should be expected for the first year. After two seasons the plant should be back to full flowering potential.
Love peonies, but disappointed in the short bloom period? Tobias suggests planting several different varieties of peonies. Selecting early and late season peonies can lengthen the bloom period to about 6 weeks!