The garden peony (Paeonia lactiflora) is among the most popular and reliable temperate climate perennials. Most gardeners are more than satisfied with the results they get: their plants bloom in late spring or early summer and produce a profusion of large flowers, often double, frequently delightfully scented. Just the plant they need to decorate their gardens or fill buckets full of cut flowers. And peonies are very long-lived: plants, many still thriving after more than 40 years in the garden, still blooming massively each year, yet require little more care than a bit of hand weeding.
Yet not all gardeners are so successful. Their peonies bloom very little if at all. Let’s take a look at the reasons why:
Problem 1: The Plant Is Too Young
Peonies are very slow-growing. A newly planted peony plant bought in a typical nursery may well take a year before it first flowers and 3 to 5 years before it’s really starting to bloom heavily. Less mature starter plants, like those inexpensive Chinese imports—or divisions you made yourself with only one or two “eyes” (buds)—can take even longer before they first bloom: 2 to 3 years! And it’s no wonder so few gardeners grow peonies from seed. You probably won’t see the first bloom for at least 3 to 5 years and it will then take them 7 to 8 years before they’re really blooming abundantly.
Be patient! Your plant will bloom … eventually!
Problem 2: Excessively Deep Planting
When you plant a peony, you have to ensure the eyes are buried, but not too deeply (about ¾ to 2 inches/2 to 5 cm). Never any deeper. Otherwise, the foliage will come out in perfect condition, but there will be no flowers … or very few.
Dig up and replant the peony at the right depth, preferably in early fall (the best time to replant a peony). Or wait. Because a peony planted too deeply will eventually correct itself and grow closer to the surface … but you may have to wait 10 years or more before it blooms.
Problem 3: Mature Peony Transplanted Without Division
Peonies simply don’t like transplantation and mature plants, with dozens of long, thick, carrotlike roots carrots, are even less enthusiastic about the idea than younger ones. You’ll often discover that a mature peony (one planted 7 years ago or more) refuses to flower after it’s transplanted, or at least, only does so after several years. Gardeners often find that when they transplant several mature peonies, at least one will begin to flower as if nothing had happened, but the majority are still stubbornly refusing to flower 4 or 5 years later.
Divisions of peonies take moving much better than mature plants transplanted with all their roots and buds intact. Dividing a peony rejuvenates it, in the sense of “making it young again.” Properly done, divisions give renewed, vigorous plants that will likely bloom the following spring. Aim for divisions with three to five eyes. If you divide the plant into smaller divisions than that, with only one or two eyes, you’ll end up with a plant that is too young (see Problem 1) and is not yet ready to bloom. So, instead aim for the middle ground: a peony that is neither a stodgy old-timer nor a wet-behind-the-ears baby: essentially, you want a full-of-pep teenage peony!
To find out when and how to divide a garden peony, read Fall is For Dividing Peonies.
Problem 3: Too Much Shade
Garden peonies are sun-loving plants and do best in full sun in all but hottest climates, where partial shade is better. In most gardens, they’ll still bloom in partial shade, but with fewer flowers and may well have weaker flower stalks. In true shade, though, the common garden peony is a total washout.
Move your peony or reduce the shade, perhaps by eliminating overhanging tree branches. Or plant shade-adapted peonies, such as the woodland peony (Paeonia obovata).
Problem 5: Foliage Removed Too Soon
After flowering, a peony rebuilds its energy supply and starts to prepare for next year’s flowering thanks to the photosynthesis its leaves carry out. They essentially “recharge its batteries.” Without them, the plant will peter away and die. And the peony is no spring ephemeral: it needs a good three months of foliage to store up the energy needed for next year’s bloom. So, its leaves must be left intact until the end of the season, at least until the beginning of September (in the Northern Hemisphere, that is). If you mow down them on purpose or by accident in July or mid-August, the plant’s ability to rebloom will be severely impaired!
Do not cut back peonies after they bloom. Leave the foliage intact until at least early fall. With many cultivars, the leaves will start to redden in September, a sign that their work is done for that year.
Problem 6: Too Much Fertilizer
It almost never happens that a peony is in soil so poor in minerals that it fails to bloom, but it will fail to bloom if it gets too much fertilizer, especially if the fertilizer is rich in nitrogen (the first of the three figures seen on the fertilizer label). The culprit is usually lawn fertilizer applied too generously right next to the peony.
Peonies are slow-growing plants, not fertilizer-guzzling weeds. With most fertilizers, apply at no more than half the recommended rate. That’s usually quite sufficient, especially if the first digit is greater than 10, as 20-5-10.
Problem 7: Late Frost
The garden peony is actually quite cold hardy and often pulls through late frosts unscathed, but a really deep, penetrating frost at the wrong time, just as the flower buds are starting to form, can kill them, leading to a year without flowers.
If you know that a severe frost is expected just as peony flower buds are starting to become visible (their most vulnerable stage), you can cover the plants with an old blanket or some other cloth, using stakes to support its weight as if it were a tent. Usually, however, it’s easier to stoically accept that sometimes Mother Nature plays dirty tricks on gardeners and wait until flowering resumes the following year. It just isn’t something that happens that often.
Problem 8: Unacceptable Growing Conditions
Every plant has its specific needs and peonies like rich, deep, fairly loose soil that is always at least a bit moist and has a pH of about 6 to 7. In addition, it’s a temperate climate plant that prefers a slightly cold to very cold winter, growing best in hardiness zones 2 to 7. In extreme conditions, such as a tropical or subtropical climate, severe aridity, rocky soil, very alkaline or very acid soil, or an abundance of invasive tree roots, etc., it will not be a very happy camper and likely will not bloom.
If you don’t have the conditions needed to successfully grow peonies, grow something else!
Problem 9: Diseases
Peonies are prone to various diseases, including gray mold or botrytis blight (Botrytis paeoniae), the one most likely to specifically harm blooms. It can kill or damage flower buds, leaving small buds black and dead and larger ones browning and unable to open. It also kills stems and leaves or provokes brown, water-soaked splotches on foliage. Diseases in general and gray mold in particular are especially frequent in cool, wet weather.
Cut off dead flower buds as soon as you see them. The plant still needs at least some of its leaves, though, so even if they are diseased, it may be better to leave the foliage in place for the summer so that what leaf surface is left can carry out photosynthesis, but do cut and destroy them at the end of the season. Applying fresh mulch annually can be helpful: it helps prevent disease spores that overwintered in the soil from migrating back up from the soil to the leaves. Ensure good aeration and good drainage at all times, even if that means you have to transplant your peony elsewhere. If the situation is repeated each spring, either apply a fungicide every two weeks … or give up on peonies.
There you go! A quick tour of nine reasons peonies fail to bloom. But don’t let the text above scare you off peonies! Yes, there can be problems, but most gardeners have no difficulties at all with their peonies and they come back to bloom massively year after year. You’ll probably find peonies among the easiest perennials you can grow!