Peony Plant Growth Stages | Life Cycle

Peonies, about 30 flower species belonging to the Paeonia genus, are surprisingly easy to grow considering just how beautiful they are in the landscape. That’s not even to mention that the peony is one of the best-cut flowers for bouquets and vase arrangements.

One of my favorite things about peony plants is that they’re perennial, so the flowers will return year after year. But those show-stopping blooms are just a fraction of the plant’s life cycle. I take a closer look at the various peony growth stages below.

Conditions for Growing Peony

As a cool-climate gardener, I’m all too familiar with the frustration that goes along with finding perennials that will survive particularly harsh winters. So it probably comes as no surprise that I have 30+ peony plants in my back garden.

The common peony (P. officinalis and P. lactiflora) and its close relatives are generally hardy in USDA zones 3 to 9. Hardiness can vary, though, so I always recommend double-checking individual varieties before adding them to your garden.

Most peonies bloom in the spring or early summer. Some varieties flower and die back within a matter of days. Others continue putting out new flowers for a couple of weeks.

Peonies are full-sun plants that need at least 6 hours of bright light per day. Tree peonies (P. suffruticosa) have more delicate petals that fare best in dappled light.

While peonies will adapt to many different soil types, you’ll see optimal health and flower production with soil that is well-draining, high in organic matter, and loamy in composition. 

Peonies prefer a soil pH of 6.5 to 7.0. Clemson University recommends amending the soil as needed prior to planting is recommended for the best results.

Whilst not essential to successful growing, fertilizer can be added to enhance the size and quantity of blooms and is also especially useful if your peonies are showing symptoms of a nutritional deficiency (and a soil test has confirmed it). Otherwise, a light application in the spring plus plenty of dug-in compost will maintain the soil quality without overfeeding.

Growth Stages Of Peony

A single peony plant can live for 100 years with proper care, the right environment, and a bit of luck. The average peony takes up to 120 days to germinate, and at least 3 years to flower after planting but will then produce new blooms each year. After flowering the seed pods for taking up to another 120 days during fall until they are fully mature.

1. Seed Germination 

Peony seeds are black, brown, or red and relatively round. The seeds feature two layers of dormancy — a tough outer coating and a dormant embryo — that ensure germination only occurs when growing conditions are perfect.

When left to its own devices, a peony seed’s dormancy will be naturally broken by changing temperatures and moisture levels in the soil. But it’s often necessary to force germination (a process called striation) when starting peony seeds indoors.

According to The American Peony Society, there are several steps required to trigger germination in peony seeds. Skipping or changing the order of these steps is likely to halt or delay germination and sprouting.

  • Step One — Soak seeds in clean water for up to 48 hours. The moisture will penetrate the outer coating and break down germination inhibitors inside the seed.
  • Step Two — Expose seeds to consistently warm temperatures between 70 and 80°F for up to 90 days or until root growth begins.
  • Step Three — Place seeds in a cool location with temperatures between 34 and 50°F. This weakens stem and leaf growth inhibitors and is the final step in breaking peony seed dormancy. It may take up to 60 to 90 days for the first leaf to emerge, at which point the plant is fully sprouted.

In total, peony seed germination can take up to 120 days or more from start to finish. Seeds that are planted in the garden without forced striation (or that self-sow from existing peonies) may take more than a full year to exit dormancy and sprout.

2. Seedlings

Once a peony seed has sprouted its first leaf, it’s safely left dormancy and can be treated like any other seedling. 

Seedlings should be moved to a warm location of about 70 to 75°F as soon as the first leaf appears. Note that relocating a peony sprout kept in a cool location prior to this leaf emerging can prevent further growth.

In most plant species, the first leaf or leaves to appear are called cotyledons. Cotyledons are simple leaves that develop inside the seed before breaking through the soil’s surface. 

Rest assured, peony seedlings do have cotyledons. But these proto-leaves don’t leave the seed. Peony cotyledons stay below the soil’s surface, providing energy to the young plant but never taking on the role of photosynthesis.

The initial shoot that emerges from a peony seed is called a plumule. In some plants, the plumule is the only stem or leaf tissue that will develop in the first year. 

3. Root Development

Peonies have thick, tuberous root systems that develop close to the soil’s surface. Even if your peony only produces one or two shoots in its first season, there is likely plenty of activity happening underground.

A healthy root system sets the stage for future stem, leaf, and flower production. It’s also essential to winter dormancy, regardless of whether the plant is 1 or 99 years old.

4. Vegetative Growth

Herbaceous and Itoh’s peonies produce brand-new vegetative growth every year in the spring and summer. This growth begins as small shoots piercing through the soil — the number of shoots per plant depends on many factors, including age, cultivar, and overall health. 

After the shoots grow to a few inches tall, the leaves will begin to unfurl. Peony leaves are deeply lobed, almost giving them the appearance of spreading fingers. 

Young peony shoots in Spring
Vegetation begins to emerge as the soil warms in spring

Tree peonies are an exception to this growth habit. These varieties produce woody stem tissue that survives year to year. New shoots and leaves grow from these existing stems rather than emerging straight from the earth. On average, a tree peony can grow up to 6 inches per year.

After about 3 years of growth, most herbaceous and Itoh cultivars reach 2 to 3 feet tall and up to 4 feet wide. Tree peony cultivars may grow up to 5 feet tall and just as wide. Keep in mind, however, that it often takes up to 10 years for tree peonies to achieve their full size.

It’s very common for herbaceous varieties to flop over as they grow, especially in the case of cultivars with particularly large and heavy flower heads. I like to employ tomato cages to keep my peonies looking tidy.

Powdery mildew can appear at any point when there is active vegetative growth. This disease is incredibly common in peonies and, to some extent, unavoidable. There are a handful of peony plants in my own garden that develop symptoms late in the growing season no matter what cultural measures I take.

Fortunately, powdery mildew is unlikely to cause harm to peony plants. It largely just looks unsightly. Affected vegetative growth can be pruned back before natural die-back to prevent the spread of the disease.

5. Bud Formation

Shortly after the leaves open up, flower buds will appear at the top of each stem. If you look closely, you can actually spot the immature buds even earlier. The buds will gradually engorge until they are about the size of a golf ball. 

The final size and exact timing of bud formation are largely determined by your climate and the peony cultivar being grown. Many varieties are categorized as early-, mid-, or late-season bloomers, and their flowering habits differ respectively.

In my garden, the first buds tend to develop within 45 to 60 days of the earliest sign of shoot emergence. But, again, this can vary greatly from one garden to another.

It’s rare to see a budding peony without also spying on a trail of ants moving up and down the stem. Ants and peonies have a mutualistic relationship, meaning that they each benefit from the presence of the other.

Many gardeners believe that the ants are actually necessary for the buds to open but, according to the University of Missouri, this isn’t true. Instead, the ants simply protect the peonies from other insects while feeding on nectar secreted by the plants’ flower buds.

Ants on Peony bud
Flower bud ready to burst open and reveal lush petals

6. Flowering

The number of days between bud formation and flowering can also vary. Some peonies in my garden open almost immediately after the buds reach their full size. Meanwhile, I’ve also had peony buds appear ‘ready to burst’ for 14 days or longer before finally opening up.

Individual peony flowers only bloom for 7 to 10 days before fading away. I recommend pruning spent flower heads as soon as they start to die back unless you plan to collect seeds. This will produce a cleaner-looking plant and, in some cultivars, encourage the development of a few more flowers.

7. Pollination

Peonies are self-fertile, meaning that a flower can be pollinated with pollen from the same plant. This is the most common form of pollination in nature. Both wind and insects are largely responsible for peony pollination. 

Cross-pollination — i.e., taking pollen from one flower and depositing it in another — can improve genetic diversity in a peony population. Gardeners may need to employ isolation and manual fertilization if cross-pollination is desired.

Take note that hybrid peonies, including Itoh varieties, tend to be sterile. In other words, these plants will not produce viable seeds no matter how they are pollinated.

8. Seed Development

Peony seeds develop and mature in seed pods that take the place of a pollinated flower. Each pod can contain up to 50 seeds.

Any seeds that are to be collected should be left on the plant until the pods are dry and leathery. This usually happens in the fall, or at least 120 after flowering occurs.

Peony seed pod ready for harvest - Peony Plant Growth Stages
Peony seed pods opening

Types of Peony

While there are dozens of species in the Paeonia genus, there are three broad categories that most garden peonies fall into:

 Buckeye Belle Herbaceous Peonies

Herbaceous Peonies

These perennials produce new stem and leaf growth each spring only to die back to the ground after a hard frost. The root tissue remains dormant under the soil before sprouting again the following spring. The vast majority of peony cultivars grown in home gardens are categorized as herbaceous.

Rockii Chinese Tree Peony

Tree Peonies

These deciduous woody shrubs do not die back to the ground in the wintertime. They do, however, drop their leaves each autumn. Due to their unique growth habit, tree peonies tend to be several feet taller at maturity than other types.

Paeonia Itoh Hybrid ‘Lolliepop’ Peony

Itoh Peonies

Hybrid peonies are created by crossing a herbaceous peony with a tree peony. Like herbaceous varieties, Itoh peonies completely die back to the ground each winter. But the size, shape, and flowering habits of Itoh peonies more closely resemble tree peonies.

All types of peonies typically start to grow when temperatures reach 65 to 70°F in the spring. As a result, the peony growing and flowering seasons can vary by several weeks from one climate to another.

If you have enjoyed this article, here’s a link to Stages of Lavender Growth that may also interest you.

FAQ Peony Plant Growth Stages

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Ben's horticultural interest grew when graduating from Hertfordshire University in 1997. Having contributed to numerous publications including Better Homes & Gardens, Garden Design Magazine, and The English Garden. He is also the author of Propagating Houseplants Made Easy.