W HEN I GET OVERWHELMED AS GARDENERS DO ABOUT NOW, I think of the peonies that grew in the narrow space between the flagstone walk and a stucco wall of the home of my youth. No matter that there was hardly room for anything in that spot, or that they’d probably been there 30 years already. Each year, during the week of my birthday, they bloomed like mad. “Onward,” they seemed to say. “Keep at it.” Sometimes, though, peonies don’t bloom well, or the buds just turn black and dry up, I’ve learned since. Want to know the reasons why?
Blooming in herbaceous peonies (and this is true for most plants) is controlled by factors like light, nutrients, the premature removal of foliage, recent transplanting, and also various plant diseases (often triggered by weather conditions). Planting depth can also affect peonies adversely. The details:
Light: Are your peonies getting enough sun, or has a nearby tree or shrub grown and reduced the amount over the years (hence a recent decline in bloom, perhaps)? Nearby trees can pose another challenge: When peonies try to compete with extensive root systems of large woody plants, they can lose…meaning reduced bloom. Peonies ideally want a minimum of six hours of full sun a day (you may be able to skimp a little in the more southern part of their hardiness range, Zone 8).
Nutrients: Overfeeding peonies, which can even happen inadvertently if they are planted beside a lawn that’s being fertilized heavily, can result in bountiful foliage and no blooms. Best to feed them compost or a balanced, all-natural organic fertilizer (never one high in Nitrogen), or some experts like bone meal. If your soil is good, just a sidedressing each year with compost will do nicely.
Foliage: The untimely removal of foliage (too soon, before it can nourish the roots below by “ripening” intact on the plant) will reduce or eliminate peony blooms. Cultivate healthy foliage all season long; cut back to near the ground only after frost.
Planting depth: With peonies there is also the “too deep” thing–they really do know if the growing points, or eyes, are buried more than about 2 inches beneath the soil surface. Though the roots will work to right themselves gradually (true!), too-deep planting can delay bloom until the plant makes its way into a better position (unless you bury it so deep it never can adjust).
Excess soil moisture: Damp, poorly drained spots will be havoc for peonies. Why waste such a wonderful plant that promises many years of reward by sentencing it to this?
Recent upheaval: Was your plant recently acquired, or recently transplanted? Peonies can sulk for a year or more after planting, especially when moved in fall, which is when they make their flower buds. Though that’s an ideal time to move them for many reasons, it can also be a bit of a distraction from their otherwise primary task of bud-production.
Diseases and weather: Cold, wet weather in spring can trouble peony buds, and some or many may be lost to fungal outbreaks. Frost is another costly factor: This year we had a freeze here when my earliest bloomers were already coloring up. Not pretty; farewell to that first crop of blooms from those plants. Other reasons buds will “blast” (fail to fully develop, often blackening first and drying up) can include the stress of dry conditions. Always clean up well around peonies and if there were fungal issues, destroy (do not compost) the affected plant parts.
Finally, a confession: I don’t grow any of the big, blowsy peonies in the garden beds here; I reserve them for a row in the out-of-the-way cutting area, which is where the ones in the photos came from. In my garden beds I prefer the scale and delicacy of species peonies, which also tend to accept a bit more shade. But then I’ve already told you that, haven’t I?
Peony information (and sources):
- Telling peony diseases apart (University of Minnesota fact sheet)