How to prune Japanese tree peonies

By

Judith Adam
Japanese tree peony (Garden Making photo)
Japanese tree peony (Garden Making photo)

There seems to be some correlation between pounding rain and peony blooming schedules. My two Japanese tree peonies were smacked down by heavy rain, but I did get to see their beautiful flowers for a fleeting day or so before the devastation. Now it’s time to assess their structure, which is a bit wonky from abusive weather. I suspect they don’t stand up well to the weight of snow accumulating in their interior structure, causing the woody stems to splay open. Fortunately, pruning is a good way to rejuvenate them.

I should point out that it’s better to prune tree peonies in early spring, when their pink buds are prominent, but not yet open. But truth be known, I’ve never done this work on time, and always get to it after the flowers are just finished, usually in early June.

Their branches live for about four years, and are replaced by new wood that sprouts every year. This natural renewal process saves quite a bit of anxiety when it comes to pruning. It’s only necessary to cut out obviously dead wood, either entire branches (cut back to the crown), or upper sections and side twigs of living branches (remove only the dead sections), cutting to just above a living bud. The end result should leave every branch with a living bud at the top. (Herbaceous peonies behave differently: their stems die back to the ground each winter and the plant sprouts new growth in the spring.)

But my tree peonies have living wood splayed open, with some branches in an almost horizontal position. As buds sprout, the weight of upward-facing new growth has no proper support and falls sideways. Flowers end up on the ground and it’s a mess! What I’ve learned is that Japanese peonies have many buds along their branches, both those that are visible and other adventitious buds hidden in the thin bark. The plants are quite responsive to pruning, and will activate their buds when living sections are removed. I just do what’s necessary, and remove any branches that aren’t sufficiently perpendicular, shaping the plant into an open form with branches leaning slightly outward and pointing upward. Taking off living wood means I’m losing some of next year’s flower buds, but the plant is quick to open buds and make new shoots.

My tree peonies got into such a mess because I was afraid to prune them. Now I see that it’s easily done, and the plants are quick to come back with new growth. So take courage and just do it.

More on how to grow peony plants

How and when to start peony plants

Print Friendly, PDF & Email

Comments

17 responses to “How to prune Japanese tree peonies”

  1. Carol Harradine Avatar
    Carol Harradine

    I have a large Peony tree that is absolutely beautiful at this time of the year, then it rains and the flowers (there are 25 this year ) get very heavy I have tried over the years to tie it up but this year it is very heavy and leggy, I don’t to loose the flowers, is there some way I can tie it up securely without damaging it.
    Thanks

    Reply
    1. Christina Lawn Avatar
      Christina Lawn

      I used the dollar store stakes that are about 3 feet long with a two inch diameter circle at the end. They are easy to install, cheap and blend in since they are green.

      Reply
  2. Sam Avatar
    Sam

    I have a gorgeous tree peony (blooms are a light peach, edged in crimson) that is probably over 15 years old. It stands about 4’ tall, so I imagine it’s a Japanese variety. I recall the tree had a slight lean to it after I planted it 12 yrs ago. With time, the lean has gotten worse. I don’t know if the plant is just growing towards the light source or just leaning more because it has gotten kinda of top heavy when in bloom? I wonder if I should try to correct the problem in the fall by partially digging it up and repositioning it? I’ve read their roots are brittle and quite deep, so do I risk root damage that will kill the plant? Another thought is to hard prune down to 4” above the ground and then in future years, selectively prune to promote the desired upright growth? It’s my favorite plant in my garden, so I would hate to lose it.

    Reply
  3. LAURIE TOTH Avatar
    LAURIE TOTH

    I live in Alberta Canada.My Peony Plants are at least a 100 years old.Tree peony’s but never get this tall.Each fall I prune them to just about 3 inches from ground level.As there growth in early spring will be damaged if trimming then.These plants came from my grandmother.They grow about 4 feet tall,full of big blooms .I have split them and moved to different areas in yard and shared with friends. We are in zone 3 lots of snow and cold.One of my favorite plants. Big roots and will bloom after transplanting the 2nd year.Now saving seeds .

    Reply
  4. Felix Avatar
    Felix

    I have three tree peony that are more than twenty years old and are over six feet tall and leggy. I was told never to prune tree peony, just prune to the nearest bud only. Should I cut it down to five feet? If I prune it down to five feet I won’t have any flower next spring.
    Thanks for your help!

    Reply
  5. Carol Avatar
    Carol

    You are correct about the tree peony coinciding with being in full gorgeous bloom and then it rains! For two years now I have pulled my garden umbrella out and protected it from the rain – getting an extra week or so of beauty!

    Reply
  6. jane denoto Avatar
    jane denoto

    I have a question about pruning my tree peony after reading this site and others. most sites say the early spring is the best time to prune – some after flowering and some before flowering and before buds break. ( February is the month for most advice) I live in southern New Jersey. If you have a very cold winter, February is prone to snow and ice, below freezing temps and not really the time you think of pruning for fear of damage to plants. Can you prune at that time??

    Reply
  7. Leon Avatar
    Leon

    Hello. My fifteen year old tree peony has been moved successfully three times and has always produced beautiful flowers, this year included. Despite watering the leaves started to wither near the roots in mid-August and eventually all of the foilage became yellow and dry. There are two other tree peonies (newer ones) within three feet of this one and they are fine. I can find no information on what went wrong. Any suggestions and how should I deal with it? Thanks.

    Reply
    1. Judith Avatar
      Judith

      Hello Leon,

      Many of the diseases affecting peonies display stunting or dwarfing of stature, gray mould, or a variety of brown or purple spots on foliage. You don’t mention these symptoms, so that eliminates several options. Powdery mildew blight can infect peonies in mid to late summer, and doesn’t always form a characteristic and visible mould on infected leaves. Powdery mildew can cause leaves to fall often, beginning with the older foliage and progressing to newer leaves (the process is reversed in other plants, such as roses, that first lose new leaves). This may be the problem that caused your peony to foliage in August. Collect any infected leaves still present and put them in the garbage, not into compost. Increasing air circulation may help to prevent this problem from occurring again next year. Pruning interior branches on this old plant to increase air circulation can also improve your chances of avoiding the disease again. If mildew should become a chronic problem for this plant, you can remove and replace it with a new selection, or spray preventatively starting in midsummer with a copper fungicide such as Bordo Mix. I hope this helps.

      — Judith

      Reply
  8. Leon Avatar
    Leon

    Tree peonies are extremely hardy and will survive almost anywhere, in both sun and shade. They prefer an airy, reasonably open situation as air movement around the plant helps prevent fungal diseases like peony wilt. However, avoid a completely exposed situation where flower petals could blow away quickly and shorten the life of the flowers. These plants begin to grow very early in the year and young developing buds can be damaged by frost if exposed to early morning sunshine.

    Reply
  9. Mitzi N. Lancaster Avatar
    Mitzi N. Lancaster

    Tree peonies are extremely hardy and will survive almost anywhere, in both sun and shade. They prefer an airy, reasonably open situation as air movement around the plant helps prevent fungal diseases like peony wilt. However, avoid a completely exposed situation where flower petals could blow away quickly and shorten the life of the flowers. These plants begin to grow very early in the year and young developing buds can be damaged by frost if exposed to early morning sunshine. Ideally, plant your tree peony where this can’t happen, i.e. a north, south or west facing aspect.

    Reply
  10. Liz Henderson Avatar
    Liz Henderson

    Hi

    I just deadheaded my tree peony and this article came at a good time, thanks. I think pruning after they bloom makes sense. I had 27 blooms on one that is only about 3-4 feet tall.
    I had a bit of a problem with it last year. The leaves had black spots and some turned mushy. It is better this year but will keep an eye on it.
    I also have a beautiful yellow one and a brilliant white one.
    The flowers unfortunately don’t last very long. I take lots of pictures.

    Thanks
    Liz

    Reply
    1. Romana Avatar
      Romana

      Last year, after blooming my 3 or 4 year tree peony turned black to the ground. I thought it was dead so I dug it up. Must have missed some because there is a peony blooming this year again. Not sure if it is true to the parent plant. Can anyone explain?

      Reply
      1. Judith Adam Avatar
        Judith Adam

        Hi Romana,
        Most tree peonies are grafted onto another peony root stock. You removed the top, but some of the root stock was left behind and is now sprouting. Is the foliage different than you remember it? Likely this will grow into a blossoming plant, although it will be different from the plant your originally purchased.
        – Judith

        Reply
    2. Judith Adam Avatar
      Judith Adam

      Hi Liz,
      Wow, that must be a beautiful plant! The mushy black spots were likely botrytis fungus, a frequent occurence in all peonies when spring weather is wet and cool for extended periods. Improving air circulation through the plant interior is often enough to avoid this. You would need to selectively thin the wood, removing some stems down to the base and making a more open plant structure. I know removing wood also means fewer flowers, but the plant would be healthier.
      – Judith

      Reply
  11. sieg Avatar
    sieg

    At what zone would it be safe to consider planting a tree peony? Thanks

    Reply
    1. Judith Adam Avatar
      Judith Adam

      Hi Sieg,
      Japanese tree peonies are cold hardy to zone 5 in Canada. For colder zones, they adapt well to growing in a large container that can be moved and wintered in an unheated garage. I hope you can try one — or several!
      – Judith

      Reply

Leave a Reply

Your email address will not be published. Required fields are marked *

Advertisements
Clicky