Perplexing Peonies

I shared the image below from a subscriber in the last newsletter and issued a call for help asking you for your input as to what was going on:

The grower was looking for help determining why their cut flower peonies were not opening. He shared the following:

These peonies were grown outside
Harvesting was going normally for about three weeks prior to this image
An application of chlorothalonil was applied about three weeks before this issue appeared
There were three cooler and rainy days about two weeks prior to the problem followed by mostly average temperatures (there were a couple days of warmer to hot days mixed in)

Let’s look at some of the replies I received:

Frost, and up-and-down weather really stops all growth.
Most likely harvested too early; bud still too tight.
Most of the real double peony (Sarah Bernardt, Kansas, Dr. Flemming) need to be harvested with a "soft" bud starting to open.
Other possible option would be cork stem. If we see a small brown area just at the base of the flower that could indicate cork stem.
Arial Botrytis. During wet times a fungicide should be sprayed more frequently. Three weeks was a long time ago. It could also be environmental or a combination of the two.
Botrytis could be the cause. Cloudy periods, bad air drainage, periods with little sunshine can cause this problem. In the worst-case scenario, the bud will rot.
Harvested later in the day when it warmed up and moved straight into a cold (34 to 36F) cooler.
Harvested and not moved into water buckets fast enough.
Contributing factor could be potassium. Environmental stresses (temp/humidity) fluctuation at a sensitive developmental stage may have created an acute and temporary stress that caused cavitation in the vascular system—just enough to interrupt the natural reproductive process.
Sounds to me like a chemical spray lockup.

This looks like a great list of possibilities. Thank you for those who responded—it's very much appreciated.

What Do I Think?

There can be several possibilities that could potentially cause peony buds to stay closed. A quick Google search will lead to options such as planting depth, insufficient sunlight, watering and nutrition, fungal diseases, weather and environmental stress, plant age, and transplant shock and pests. Similar to your possibilities listed above, these also seem like very plausible options.

I'm not a peony expert, but three possibilities came to my mind when I first saw the image above:

Frost. Exposure to a major frost event after the buds are set can often do screwy things to flowers; this includes stopping them from opening.
Cool, cloudy weather with very little sun. This seems like legit even if I don’t fully understand how peony flowers develop over time (from bud to open flowers).
A problem called "balling." Flower balling is a disorder in which flower buds develop normally, but do not open. Cool, wet weather saturates the outer petals and then the sunshine dries and fuses them into a tight, papery shell, preventing the bud from opening.

If I were asked to narrow it down to one possibility. I would select option #3—balling. This seems like the most logical explanation out of all the options you or I have come up with. Basically, the failure of the buds opening is due to environmental conditions, but I wouldn’t say it’s an environmental response. From my understanding, water gets into the bud and then dries very quickly, causing the petals to fuse together, therefore, they cannot develop and open normally.

More on Balling

The phenomenon referred to as balling also occurs with other flowers such as roses and camellias.

What is rose balling? Rose balling normally happens when a rosebud forms naturally and begins to open, but once the new swollen bud gets rained on, soaking the outer petals, and then subsequently dries too quickly in the sun’s heat, the petals fuse together. This fusion doesn't allow the petals to unfurl like they normally would, resulting in rosebuds dying before opening or failing to open at all. Eventually, the fused ball of petals dies and falls off of the rose bush. If seen by the gardener prior to falling, the bud may appear to have been infected with mold or fungus, as the buds can become slimy once it starts dying.

Plant pathogens, such as Botrytis, often get the blame when balling occurs, however, diseases are often a secondary issue.

Unfortunately, there isn’t much information out there on balling. The Royal Horticultural Society has this on their website: Flower Balling.

Thanks again to those of you who submitted your thoughts on this challenge.

Darwin Perennials Day

I attended Darwin Perennials Day at the beautiful Gardens at Ball in West Chicago last week.

The gardens were very nice, but, unfortunately, the weather was not. It began to rain shortly after we all arrived and then the rain continued to intensify and didn't stop. Karl Batschke, General Manager of Darwin Perennials, jokingly pointed out that it only rains the years that I attend the event.

Come to think of it, I think there's some truth to Karl’s statement. I recall one time in the early years of Darwin Perennial Days that it rained cats and dogs and the area was under severe weather warnings causing us to take shelter (mandatory) until the storm passed. I can’t say that it's rained every time I’ve gone, but, objectively, it has rained during most of them.

Someone else was saying that it only rains on Wednesdays during the weeks the event is held and maybe they should schedule it for a different day of the week. Is it coincidental that it almost always rains at Darwin Perennials Day and that it only rains on the Wednesday of these weeks? I’m not sure about that, but I'll be sure to bring my raincoat, rain boots and umbrella next year.

Let’s Take a Look at What I Saw

Not all the perennials I’m about to show you are new varieties, but these are plants that were planted between 2024 and this year and looked great in the garden beds. Here are several of the standouts (even during the rain). I’ve listed the year the plants in the images were planted and their hardiness zones.

Gaillardia Guapa Flamenco Bicolor

Here's a bold and reliable gaillardia with bright bold colors, a compact habit and long bloom time (late spring well into the fall). It’s deer resistant and hardy to Zone 5. This group was planted in 2026.

Penstemon Mountain Treats Lavender

With its large flowers and reblooming ability Mountain Treats Lavender is a high impact plant. It blooms all summer and is an absolute hummingbird magnet. Planted in 2026 and is cold hardy to Zone 6.

Coreopsis Sunfetti Yellow Bicolor

It may not have the largest flowers on the market, but Sunfetti Yellow Bicolor produces tons of them. It grows fast and blooms from spring into the summer months. Planted in 2026 and hardy to Zone 5.

Geranium Purple Glow

This deer-resistant selection has a vigorous, low-growing mounded habit with excellent flower coverage. It blooms from early spring to the early summer. Planted in 2025 and cold hardy to Zone 3.

Hemerocallis DayScape Golden Yellow

This is quite an impressive early blooming daylily. Not only that, but it also blooms continuously and is highly resistant to rust. This cultivar and series are sure to give Stella de Oro and other daylilies a run for their money. It was planted in 2024 and is cold hardy to Zone 4.

A Few More

It takes more than heavy rain to keep a perennial nut like myself from spending time in the perennial beds. Here are a few more perennial standouts:

Veronica Moody Blues Mauve

Who doesn’t love the architecture a veronica brings to the landscape? Moody Blues Mauve blooms continuously beginning in the spring and attracts pollinators, but not deer into the gardens. This group was planted 2024 and is hardy to Zone 4.

Sedum Wineberry Delight

I wasn’t the only one that stopped and snapped images of this good-looking sedum (it’s actually from Walters Gardens). It has dark foliage that contrasts nicely with the surrounding landscape. Planted in 2026 and cold hardy all the way to USDA Hardiness Zone 3.

Achillea New Vintage Violet

This is an outstanding, colorful achillea that always appears full and blooms from late spring through late summer. It’s great for pollinators and is also deer resistant. Planted in 2025 and hardy to Zone 4.

Heuchera Carnival Cinnamon Stick

This colorful heuchera of copper shades looks like a great performer. It has a nice mounded habit and the leaves differ in color by their age and where they're located on the plant. It’s heat tolerant and hardy to Zone 4. This group was planted in 2024.

You can get more information on these perennials, as well as their entire lineup, by visiting the Darwin Perennials website.

My email is paul@pace49.com if you have any comments, article suggestions or if you'd just like to say hello.

Best regards,

Paul Pilon

Editor-at-Large—Perennial Pulse

National Sales Manager—Pace 49, Inc.

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