When to Split Peonies?

Peonies were first brought to America during the 1800s. The easy to grow plants with fragrant, large, showy flowers and dark green foliage were winter hardy and quickly became a favorite in the home garden. They are low maintenance plants that experience very few disease and pest problems.
Peony plants can live as long as 50 years when taken care of properly. The plants are easily propagated when crown division occurs at the right time.

Plant Age

• Choose peonies that are at least two years old, mature and large enough to have between one and three visible crown buds per planned division. It takes as long as three years for peonies to become established and produce flowers. Never divide an immature or young plant. Dividing the peonies while they are immature results in poor plant establishment, growth, health and flower production in subsequent years.

  Choose and prepare the site for transplanting well ahead of time if at all possible. For fall planting, prepare the soil during the spring. Amend the soils with generous amounts of compost, well-rotted manure or peat moss.

Season

• Divide peonies in the early fall through crown division. Peonies fare better when plant division occurs in the fall before the ground freezes, rather than in the spring. The dormant plants are less susceptible to injury during this period. Towards the end of August or beginning of September, cut the foliage of the peony back to ground level.

  Thoroughly water, but do not swamp, dry plants the day before digging them up. Dig up the plant. Set aside in a shaded area for a few hours until the plant begins to soften up. Carefully divide the peony plant with a garden spade or a long knife. Ensure that there is at least one visible crown shoot per each new division. Extremely long roots can be trimmed back to 6 or 8 inches in length.

  Dig a hole at least a foot deep and amend the soil with compost or well-rotted manure. Plant the peony divisions so that the crowns are 2 inches below the soil surface.

Protection

• Water the newly divided peonies thoroughly after planting. Cover the new transplants with a thick layer of mulch to protect them throughout the winter months. The repeated freezing and thawing of soil that may occur during the winter may heave young plants out of the ground and damage young, newly established root systems. Remove the mulch in the spring at the first sign of emerging green shoots.