It’s peony season here in Minnesota, which usually means an abundance of blooms and a few peony problems. Peonies are a heritage plant in our part of the world and typically bloom for a couple of weeks in early summer. We have several peony breeders in the state and some hold open days during this time of the year.
On the whole, they are one of the easiest, most care-free and long-lived plants in the garden, but there can be a few peony problems. This year, the heat is a small issue. We’ve set heat records this week, and that means the plants will bloom and fade quickly. Like a lot of other gardeners, I’ve been running around snipping buds just before they bloom to bring them into the house. They last a bit longer in the vase and I can enjoy their scent while hiding from the heat.
Here are four more common peony problems and what to do about them.
Flopping
Easily the most common peony problem is that they flop over. Peony blooms are large compared to their stems. Add some rain or a windy day and they end up bloomside down on the ground. Installing plant supports early in the season is the best way to prevent flopping. I’ve used a variety of supports both half-circle supports and full circle supports, and the full-circle supports work best for peonies. Get metal rather than plastic, if you can afford it, and look carefully at the size of the support before buying. Some gardeners use modified tomato cages as supports, too.
Whichever support you choose, get it on the plant early—preferably before or just as shoots emerge in spring. Even with a support, you may have a bloom or two flop over. Just pick it and bring it into the house.
You can also choose varieties of peonies that have been bred to have stronger stems. Many of these are Itoh peonies, which are a cross between tree peonies and herbaceous peonies. The heritage peonies that I love are floppers, so support is mandatory.
Powdery Mildew
I’m facing a case of powdery mildew on one of my peonies this year. Powdery mildew is a fungal condition that flourishes when plants are in damp or stressful conditions. It has not been a wet year, but this particular peony is planted next to a garage wall and very close to a small tree and other peony. The conditions are not ideal as peonies do best with plenty of sun and lots of air flow around them.
There are a variety of sprays and concoctions you can try to reduce powdery mildew—most contain a horticultural oil, such as neem oil. However, the University of Minnesota and many other experts recommend just tolerating powdery mildew during the growing season. At the end of the season, you should be sure to remove all the infected leaves from the area. Given how bad my powdery mildew is, I plan to prune out some of the peony stems after blooming to give the plant more airflow. In the fall, I’ll collect all the leaves and stems and put them in the trash.
Should I move my Duchesse de Nemours peony? That’s an option, but it should not be done until September. I have a few sunnier, more open spots in my front garden that would look great with a peony in them. Moving the peony might bring on the next peony problem, however.
Not Blooming
Every now and then, a peony will not bloom. There are lots of reasons peonies don’t bloom and most of them are of short duration. For instance, if I move the powdery mildew peony, it might not bloom next summer. Peonies last up to 100 years, but it takes them awhile to get accustomed to a new location. Other reasons peonies might not bloom are that they were planted improperly (usually too deeply), over-fertilized, or planted in a place with too little sun. If your peony was planted in the past couple of years, don’t worry too much about the lack of bloom. After that, however, you may want to consider other reasons why it might be not be flowering.
Botrytis Blight
Another common peony problem is botrytis blight. It’s also called gray mold and is another fungal disease that occurs most often during wet growing seasons. It can be devastating, causing stalks to rot and buds to fall off. Initially, the disease looks almost like your peony has blackspot, which circular reddish brown spots on the leaves. Buds will be brown and crusty.
Like powdery mildew, cleaning up the foliage in the fall and disposing of it is one step to prevent the disease from taking hold. Encouraging drainage and air circulation and planting peonies in sunny conditions also helps. Do not compost diseased foliage to prevent further spread of the disease.
These are not the only problems with peonies but are the most common. Overall, peonies are easy care, long lasting and beautiful. Every northern garden should have at least one.
I bought 2 peony bulbs in packs from Bunnings. I planted them according to the instructions about 8 weeks ago. Nothing has happened. No sign of life.
I’m not sure where you are from Christine, but if you are in Minnesota, you won’t see anything until next summer. Fall planted peonies usually do not produce foliage until the following spring.
My one peony bush looks healthy; it’s about 20 years old. The blooms are softball sized and very fragrant but I only get about 10 blooms
Is it possible to make it produce more?
What is the sun situation where you have them planted? The low number of blooms could be related to too much shade, especially if trees have grown up around the bush over the past 20 years. Another reason might be that the foliage was cut back too soon last summer? Here’s a good post from Iowa State on why peonies might not bloom.
I’m in central Iowa. My peonies have browns spots all over the leaves & stems. Also the glues sworm all over them. They are not blooming open. What can I do?
Could it be this? https://hortnews.extension.iastate.edu/faq/there-are-large-brown-spots-my-peony-leaves-what-should-i-do
The post does not mention not-blooming as a symptom. My peonies have been slow to bloom this year (none are open yet) but I would guess they should be open by now. If it is a fungal disease, you may want to move the peony in fall — the one I moved last year looks much healthier now and will have a few blooms. I expect more in 2023.
I have a yellow tree peony that is about four feet tall and quite bushy. It is planted in mostly sun. For the last couple of years the blooms seem to be hidden within the foliage so it is not very showy. Should I be pruning it or what.
Unlike herbaceous peonies,tree peonies do require some pruning. This post offers the basics of what to prune and when: https://www.thompson-morgan.com/pruning/tree-peonies
Even with my herbaceous poenies, I remove spent stalks and floppy branches after blooming to make sure the foliage is attractive through the summer.
My peony has buds that never fully open. It been happening the past few years… I’ve tried watering more frequently and fertilizer but nothing seems to help.
Do they shrivel up? It could be botrytis blight. Here’s a link to a bunch of reasons peony buds may not open. It sounds like you have addressed a few of the possibilities. Planting depth or lack of sun might be another possibility.
https://www.gardeningknowhow.com/ornamental/flowers/peony/why-your-peony-buds-but-never-flowers.htm
My grandmother planted my peonies so they are probably more than 30 years old. This year I only had two flowers. They are not diseased – leaves and stems are healthy. I have not moved them. And I have weeded them. What should I do before next summer so they bloom?
Is it possible the light has changed? If they have bloomed in that spot before, it may be something in the environment has changed, such as trees getting bigger or an addition to a house that is shading the area. It may also be the soil is a bit tired — maybe add a layer of compost this fall and then fertilize them next spring. Here’s a good article on how and when to fertilize peonies: https://savvygardening.com/fertilizing-peonies/
Good luck!
Thank you so much. I will fertilize this fall, and check the light. When the tornado came through, it took my neighbor’s shed with it and she re-built it and moved it back so it may very well be the light as well. I so appreciate the suggestions!
I planted Itoh peony tubers in May. They are only about 5 inches tall. is this expected?
If I did plant them too deep, can I replant them now
Itoh peonies do grow a bit slower than herbceous, in my experience. The “eyes” of the poeny (where the foliage shoots come from the root) should be only 1 inch below the depth of the soil. If you choose to replant, fall is the best time to do it — so anytime between now and mid-September would be great.