The permanence of peonies is one of the qualities that make them such an enduring perennial in the garden. However, the same features that make peonies a sturdy and long-lived plant can also make them a challenge to transplant. Sometimes a move becomes a necessary alternative to plant loss. Perhaps that peony you installed a decade ago beside a young sapling today flounders in the shade of a now-mature oak tree. Or, you've decided to add a gazebo or patio to your landscape, and a special peony stands in the way of progress. Finally, you or a family member might be moving away, and you can't bear to leave behind an heirloom peony plant, that has become as necessary and dear as a family pet. Learn about the timing and steps required to complete a successful peony transplant.
When to Transplant Peonies
Knowing when to transplant your peonies is half the battle of a successful move. For peonies, fall is the ideal time to dig up the plants. The exact timing differs by region, but mid-August for Northern gardeners and early November for Southern gardeners is a general guideline. In the fall, peonies are preparing for dormancy. Their metabolism slows, causing growth and development to stop. This change helps perennial plants save energy, and minimizes stress to roots during the move.
If it's April, and you're preparing for a move this month, weigh the possibility of plant damage or death against your desire to take the plant with you. Severely stressed plants may not bloom again for several years and may be vulnerable to attack by fungal diseases or insect pests.
Choose a Site to Replant
Peonies need full sun to get the energy to create those massive blooms. Because peonies only bloom once a year, it's disappointing to get only a few blooms straining toward the sun. Choose a site that gets at least six hours of full sun each day. The north side of your home will not provide this. If you are using peonies as a foundation plant, the east or south side of your home will have the strongest light.
How to Dig up a Peony
Don't skimp on the rootball you will need to dig up when transplanting a peony. A peony's health begins with the health of the rootstock, so you will want to preserve as much as you can while minimizing any damage that might provide a pathway for insects or diseases. Measure at least 18 inches from the crown when you start digging. Dig straight down, and pause to pry around the rootball until you feel the entire plant begin to lift. Do not lift the plant by the stems; breakage will ensue. If the rootball is too heavy to lift from its hole, gently wash away some of the soil from the roots.
Prepare the Soil for Peonies
Peonies need soil with good drainage. Neither sticky clay nor sandy gravel will yield a healthy peony, but the cure for both situations is the same: amending the soil with compost. Mix it in 50/50 with the native soil. You don't want to create a planting hole that's so enriched and fluffy that the roots never want to extend beyond it; rather, you must give your transplanted peony a booster to alleviate shock while also encouraging adaptation to the new home.
How Deep to Place the Peony
Peony planting depth is a critical matter that will determine future blooming for decades. To determine the ideal planting depth, locate the eyes on the peony rootball. This is one of those plant terms that doesn't make much sense, but if you think of the eyes as buds and look for pinkish nubs at the base of the crown you will locate them. These eye buds are next year's flowering stems. If you bury them too deeply, they will never emerge and develop. Place them just beneath the soil's surface, no more than 2 inches deep. This is true even in cold climates. No worries, as these dormant eye buds will not be damaged by frigid winters.
After the Peony Transplant
Fill by hand the planted hole back with your amended soil. The dexterity of hands is better than using garden tools here, as you can gently tamp the soil down and ensure that there are no air pockets without damaging the roots. Water well, but don't oversaturate the soil. It shouldn't be necessary to water again unless your weather forecaster says that a true drought is happening. Peonies are entering their dormant state now, and going to bed for the winter in a soggy bed is an invitation to rot. When spring arrives, look for emerging reddish-purple stems to let you know that your peony has settled into its new home.