What Is a Peony Bloom Date? (and Why It Matters)
What Is a Peony Bloom Date?
This is one of the most common questions we hear—from online customers and visitors to the farm alike.
What exactly is a peony bloom date?
The answer is simple, and once you understand it, bloom dates can be a powerful tool for choosing the peony (or peonies!) that are best for your garden.
Understanding Peony Bloom Dates
Peony bloom date ratings—sometimes called peony bloom weeks—are a more precise way to describe when a peony variety will bloom. They go beyond the general labels of early, mid-season, or late by assigning each variety a specific place within the peony bloom season.
Peonies bloom over a seven- to eight-week period, and each variety is generally consistent in its timing from year to year. While weather can influence bloom times—and different varieties respond differently to changing conditions—extensive, reliable research helps gardeners accurately predict when their peonies will bloom.
The Bloom Date Project
For many years, catalogs and garden centers relied on broad terms like “early,” “mid-season,” and “late,” which led to inconsistencies between varieties. To address this, the American Peony Society collected bloom data from numerous locations over long periods of time. The result is the Bloom Date Project, which established a standardized “common bloom period classification system.”
How Bloom Week System Works
In this system, the peony ‘Red Charm’ serves as the reference point and is classified as Week 4, Day 0.
Varieties that bloom before Red Charm fall into Weeks 1–3
Varieties that bloom with Red Charm are classified as Week 4
Varieties that bloom after Red Charm make up Weeks 5–7, with a few extending into Week 8
Each peony’s bloom date is measured in relation to when Red Charm blooms.
Why Bloom Dates Matter
Bloom dates are especially helpful when designing a peony garden.
One approach is to extend the bloom season by selecting varieties that span all eight weeks. This means fewer peonies blooming at any one time, but a longer overall season of flowers.
Another approach is to choose varieties—or even just one—that all bloom at the same time. The result is a spectacular, short-lived burst of peonies that’s absolutely stunning, then gone until the following year.
There’s no right or wrong choice. Bloom date ratings simply give gardeners the information they need to design a garden that fits their vision.
Final Tip
When browsing peonies, look for the bloom date rating or bloom week—it’s one of the best tools for choosing the perfect varieties for your garden.