Transplanting Peonies Is Not That Difficult
Many people are understandably hesitant when it comes to transplanting peonies. Peonies tend to be very long living plants, often blooming profusely for many years. When a plant has been in the same spot for 20 or 30 years, it's understandable to get second thoughts about moving it. It has also been said by some that peonies should not be transplanted, and doing so will kill the plant.
Fall Is Best, But Spring Will Work - How a peony reacts to being transplanting, depends partly on when you do it and partly on how you do it. In general, transplanting peonies in mid-summer is not a good idea as they will certainly wilt and probably die. This is true of many plants. A hot summer day is not a good time to transplant anything and hot, dry weather will place a great deal of stress, often too much, on a plant that is being transplanted. Autumn is the best time, but this is not a hard and fast rule. You can transplant peonies in the springtime as well. In fact if you are faced with a situation where you must transplant an established peony (because of construction, or it's a favorite plant and you are moving), you can do it at any time. It's just that mid-summer is not the best time, nor is mid-winter in many places, so you do your best and cross your fingers.
If You Can't Wait An Extra Year, Don't Transplant - One thing is certain. You will set the plant back. This isn't necessarily bad; it's just that during the first season following transplanting, the peony may give few blooms or none at all. Usually by the second, and almost always by the third season, the plant will be back in its prime. There is also the possibility that transplanting may actually be best for the plant. A peony plant will very often give many beautiful blooms for many years, and then its performance will begin to decline. If that happens, you can dig up the plant, divide the roots, and transplant several smaller clumps. In a couple of years you should have several plants blooming just as well as the original plant ever did. You may read somewhere that peonies should not be divided, but that simply isn't true. Peonies take to dividing quite well. Again, be prepared for the plants being set back for one and possibly two growing seasons. As is the case with transplanting peonies, dividing them will give optimum results when done in the fall after the foliage has died back.
When you are preparing to dig up the peony for dividing or transplanting, dig a foot or two from the stems to avoid as much as possible cutting off side roots. If you cut too close and end up with few roots, the transplant may not survive, or may be set back considerably. Wash the roots off and then prepare to place them in their new home.
A Big Hole In A Sunny Location - When transplanting peonies, they will do best when placed in a hole that is somewhat bigger than the root ball, which may be quite large and quite wide. You should cover the buds with about an inch of soil but not much more. If you cover the buds with more than two inches of soil, the plant will grow the following spring but may never produce blooms in any quantity. If you live in a cold winter region it's always a good idea to place a layer of mulch (bark, straw, pine needles) over the plant, removing the mulch first thing in the spring. If you've had peonies for any length of time, you'll know that they are sun worshipers, so when transplanting them or dividing them, avoid shady locations, and make sure they are planted in soil that is well drained.
If you have an heirloom peony in your yard that either must be moved, or appears in need of dividing and a fresh start, choose a cool time of the year, fall is best, plant it where it will get lots of sun, and remember the plant will take a year at least to completely recover. Peonies are very hardy plants, and are not fussy, so with any luck at all, you should be OK.