Complete Guide to Peony Varieties and Classification

Peonies are among the most beloved perennial flowers, prized for their spectacular blooms, longevity, and rich fragrance. Understanding peony classification helps gardeners select the right varieties for their climate, garden design, and blooming preferences. This florist guide covers the major types, varieties, and classification systems used for these magnificent plants.

Botanical Classification

The Genus Paeonia

All peonies belong to the genus Paeonia, which contains approximately 40 species distributed across temperate regions of the Northern Hemisphere. Botanists divide this genus into three distinct sections based on growth habits and evolutionary relationships.

The first section, Paeonia, encompasses all herbaceous peonies that die back to ground level each winter. These plants are the most familiar to gardeners and include the classic garden varieties that emerge fresh each spring from their underground crowns. Most herbaceous peonies are native to temperate regions of Europe, Asia, and western North America, where they have adapted to cold winters and warm summers.

Section Moutan contains the tree peonies, which are actually woody shrubs rather than trees despite their common name. These remarkable plants maintain their branching structure throughout the year and can grow into substantial shrubs reaching 3 to 7 feet in height. Tree peonies are primarily native to mountainous regions of China, with some species extending into Tibet and Bhutan, where they grow in well-drained soils at considerable elevations.

The third section, Onaepia, represents a fascinating group of hybrid plants created by crossing herbaceous and tree peonies. Also known as intersectional peonies or Itoh hybrids, these plants combine characteristics of both parent types. This relatively new group emerged from successful hybridization work that began in the 1940s, though widespread availability only developed in recent decades.

Major Peony Types

Herbaceous Peonies

Herbaceous peonies form the backbone of most peony collections, deriving primarily from Paeonia lactiflora, the Chinese peony that has been cultivated for over a thousand years. These plants completely disappear underground during winter dormancy, then emerge with remarkable vigor each spring to produce their spectacular display of flowers and attractive foliage.

The growth cycle of herbaceous peonies follows a predictable pattern perfectly adapted to temperate climates. In early spring, distinctive red or pink shoots push through the soil, rapidly developing into sturdy stems that can reach heights ranging from 18 inches to 4 feet depending on the variety. The deeply divided foliage provides an attractive backdrop for the flowers, which typically appear in late spring to early summer, generally during May and June in most temperate regions.

Most herbaceous peonies demonstrate remarkable cold hardiness, thriving in USDA zones 3 through 8, with some varieties surviving even colder conditions. This cold tolerance, combined with their longevity, makes them exceptional garden investments. A well-planted herbaceous peony can continue blooming for 50 years or more with minimal intervention, often improving with age as the root system becomes more established.

Beyond the dominant P. lactiflora, several other herbaceous species contribute to garden diversity. Paeonia officinalis, the European peony, offers earlier blooming and more compact growth, making it valuable for extending the season and fitting into smaller garden spaces. The fernleaf peony, P. tenuifolia, brings unique feathery foliage and deep red flowers to the garden, while P. mlokosewitschii, affectionately known as "Molly the Witch," produces rare single yellow flowers that are highly prized by collectors.

Tree Peonies

Tree peonies represent the aristocrats of the peony world, producing some of the largest and most spectacular flowers in the genus. Despite their common name, these plants are deciduous shrubs that develop permanent woody frameworks, distinguishing them clearly from their herbaceous relatives that disappear each winter.

The most striking feature of tree peonies is their early flowering habit, which typically occurs in April and May, several weeks before most herbaceous varieties begin blooming. This early season display provides gardens with magnificent color when few other plants are at their peak. The flowers themselves often surpass herbaceous peonies in size, with blooms reaching up to 10 inches across in some varieties, creating an almost overwhelming display of petals and color.

Tree peonies generally show good cold hardiness in zones 4 through 8, though their early flowering habit can make them vulnerable to late spring frosts in some regions. Gardeners in areas prone to late freezes often position tree peonies in locations that receive morning shade to delay bud break, or provide temporary protection during critical periods.

The classification of tree peonies reflects their geographic origins and breeding history. Chinese tree peonies, derived primarily from P. suffruticosa, represent the oldest cultivated forms with hundreds of named varieties developed over centuries of selection. Japanese tree peonies emerged from Chinese stock but were developed through different aesthetic preferences, often emphasizing cold hardiness and distinctive flower forms. Modern European and American tree peony breeding focuses on adapting these magnificent plants to local climates while developing new color combinations and improved garden performance.

Itoh Peonies

Itoh peonies, named after their Japanese breeder Toichi Itoh, represent one of the most significant achievements in modern peony breeding. These intersectional hybrids combine the best characteristics of both herbaceous and tree peonies through complex hybridization techniques that were once thought impossible.

The breakthrough in creating Itoh peonies came from overcoming the chromosomal barriers between herbaceous and tree peony species. While herbaceous peonies typically have 10 chromosomes and tree peonies have 5, successful hybridizers found ways to create fertile offspring that combined traits from both parents. The resulting plants exhibit the herbaceous growth habit of dying back each winter while maintaining the sturdy stems and extended flowering period characteristic of tree peonies.

One of the most remarkable features of Itoh peonies is their extended blooming period, often lasting several weeks longer than either parent type. The flowers frequently display colors unavailable in herbaceous peonies, particularly clear yellows and unusual color combinations that change as the flowers mature. Popular varieties like 'Bartzella' produce pure yellow blooms with red flares, while 'Julia Rose' offers flowers that progress through multiple color phases during their lifespan.

Itoh peonies typically grow 2 to 3 feet tall and demonstrate good cold hardiness in zones 4 through 8. Their sturdy stems rarely require staking despite supporting large flowers, and their foliage often provides attractive fall color before dying back for winter. While these hybrids command premium prices due to their complex breeding and limited propagation, they represent excellent long-term garden investments.

Flower Form Classification

Single Peonies

Single peonies showcase the elegant simplicity that characterizes wild peony species, featuring a single row of five to ten broad petals surrounding a prominent center of golden stamens. This flower form offers several advantages in garden situations, particularly for gardeners who appreciate understated beauty and wildlife-friendly plants.

The exposed stamens of single peonies provide excellent access for pollinators, making these varieties particularly valuable in ecological gardens. Bees and other beneficial insects readily visit single peony flowers, and the pollen-rich centers support diverse pollinator populations. Additionally, single flowers typically prove more weather-resistant than complex double forms, maintaining their appearance through wind and rain that might damage more elaborate flower forms.

Outstanding single varieties include 'Krinkled White', which produces pristine white flowers with distinctively textured petals, and 'Sea Shell', renowned for its perfect pink blooms and reliable performance. 'Flame' offers brilliant red single flowers that create stunning focal points in the garden. These varieties often bloom reliably year after year with minimal maintenance, making them excellent choices for low-maintenance landscapes.

Japanese and Anemone Forms

Japanese form peonies, also called anemone form, present a distinctive flower structure that combines the simplicity of singles with added complexity in the center. These flowers feature a single row of broad outer petals, called guard petals, surrounding a center filled with modified stamens known as staminodes. These staminodes often display different colors than the outer petals, creating striking two-toned effects.

The unique structure of Japanese form peonies provides exceptional garden value through their distinctive texture and extended interest. The staminodes may appear as narrow, petaloid structures or more elaborate formations, depending on the specific variety. This flower form originated in Japanese breeding programs but has gained worldwide appreciation for its sophisticated appearance.

Excellent Japanese form varieties include 'Do Tell', which combines pink guard petals with cream-colored staminodes for a particularly elegant effect. 'Bowl of Beauty' offers rose-pink outer petals with cream centers, while 'Nippon Beauty' provides deep red guard petals with golden staminodes. These varieties excel as cut flowers due to their unique appearance and good vase life.

Semi-Double and Double Forms

Semi-double peonies occupy the middle ground between singles and full doubles, featuring multiple rows of petals while retaining some visible stamens in the center. This flower form provides fuller appearance than singles while avoiding the potential structural problems of very heavy double flowers. Semi-double varieties often combine the best aspects of both flower types, offering substantial blooms without requiring extensive support.

Double peonies represent the ultimate expression of floral abundance, featuring multiple layers of petals that completely obscure the reproductive parts of the flower. These varieties create the classic "peony" appearance that many gardeners expect, with rounded, densely petaled flowers that can reach enormous proportions. The most elaborate double varieties may contain over 100 petals in a single flower.

Classic double varieties like 'Sarah Bernhardt' produce soft pink flowers with exceptional fragrance and reliable performance, while 'Festiva Maxima' offers pure white blooms with occasional red flecks that add character. 'Karl Rosenfield' provides deep red double flowers that create dramatic garden focal points. However, gardeners should be aware that the largest double varieties may require staking to prevent stems from bending under the weight of heavy flowers, particularly during rainy periods.

Bomb Type Peonies

Bomb type peonies present a distinctive flower structure featuring broad outer petals that surround a raised, densely packed center of smaller petals. This formation creates a rounded, compact appearance that differs from both traditional doubles and Japanese forms. The outer petals typically lie flat or slightly cupped, while the center petals form a distinctive mounded structure that gives bomb peonies their characteristic appearance.

This flower form provides exceptional garden impact due to its unique structure and typically excellent substance. Bomb type peonies often display good weather resistance and maintain their form well throughout their blooming period. The raised center creates interesting shadows and depth that enhance the visual appeal of individual flowers.

Notable bomb varieties include 'Red Charm', an early-blooming variety that produces deep red flowers with excellent garden performance, and 'Monsieur Jules Elie', a classic pink bomb that has been garden favorite for over a century. These varieties work particularly well in formal garden settings where their structured appearance complements architectural elements.

Color Classifications

Traditional White Peonies

White peonies provide garden elegance and versatility that few other flowers can match, serving as both stunning focal points and harmonious companions to other garden plants. Pure white varieties like 'Duchesse de Nemours' and 'Festiva Maxima' offer clean, crisp coloration that brightens shaded areas and provides cooling contrast during hot summer weather.

The range within white peonies extends from pure snow white through various cream and ivory tones. 'Shirley Temple' produces soft pink buds that open to cream-colored flowers, gradually fading to pure white as they mature. 'Moon of Nippon' offers pristine white flowers with subtle ivory undertones that add warmth to the coloration. These color variations allow gardeners to create sophisticated monochromatic plantings with subtle tonal differences.

White peonies prove particularly valuable in evening gardens, where their pale flowers seem to glow in twilight conditions. They also photograph beautifully and serve as essential components in bridal bouquets and formal floral arrangements. Many white varieties also offer exceptional fragrance, adding sensory appeal to their visual beauty.

Pink Peony Variations

Pink peonies encompass the largest color group within the genus, ranging from the palest blush tones through vibrant coral shades to deep rose and magenta hues. This extensive color range allows gardeners to create sophisticated gradations and harmonious combinations within their peony plantings.

Light pink varieties like 'Sarah Bernhardt' provide soft, romantic coloration that complements pastel garden schemes and creates gentle focal points without overwhelming surrounding plants. These pale pinks work particularly well in cottage garden settings and informal landscapes where subtle color transitions create pleasing effects.

Deep pink varieties such as 'Dr. Alexander Fleming' and 'Big Ben' offer more dramatic impact, creating bold statements in the garden while maintaining the classic peony appeal. These deeper tones provide excellent contrast against dark foliage and work well in more formal garden settings where stronger colors are desired.

Coral pink peonies represent some of the most exciting modern developments in peony breeding. Varieties like 'Coral Charm' and 'Coral Sunset' offer warm, salmon-pink tones that change subtly as the flowers age, providing extended color interest throughout their blooming period. These coral tones bridge the gap between traditional pinks and yellows, offering unique coloration that complements both warm and cool garden color schemes.

Red Peony Spectrum

Red peonies provide the most dramatic color impact in the peony palette, ranging from bright scarlet through deep crimson to rich burgundy tones. These varieties create powerful focal points in the garden and work particularly well as specimen plants or in locations where bold color statements are desired.

True red varieties like 'Red Charm' and 'Kansas' offer bright, clear coloration that maintains its intensity throughout the blooming period. These varieties work well in contemporary garden designs and provide excellent contrast against green foliage or pale companion plants. Their vibrant color also makes them outstanding choices for cut flower arrangements where maximum impact is desired.

Deep red and burgundy varieties such as 'Karl Rosenfield' and 'Old Faithful' provide richer, more sophisticated coloration that works well in formal garden settings. These darker reds often develop more complex color depths as the flowers mature, creating subtle color variations within individual blooms. 'Chocolate Soldier' represents the darkest end of the red spectrum, offering deep burgundy flowers with almost black undertones.

Specialty Color Developments

Yellow peonies represent one of the most exciting developments in modern peony breeding, though this color remains relatively rare and primarily confined to tree peonies and Itoh hybrids. The absence of yellow pigments in herbaceous peony genetics has made yellow coloration one of the holy grails of peony breeding, achieved only through complex hybridization programs.

Tree peony varieties like 'High Noon' and 'Souvenir de Maxime Cornu' produce clear yellow flowers that represent centuries of Chinese breeding work. These varieties offer pure yellow coloration often enhanced by red or purple flares at the petal bases, creating striking color combinations unavailable in herbaceous types.

Itoh hybrids have revolutionized yellow peony availability, with varieties like 'Bartzella' and 'Garden Treasure' bringing reliable yellow coloration to herbaceous-type plants. These hybrids often feature flowers that change color as they mature, starting with deep yellow tones and gradually fading to cream or white, providing extended color interest throughout their blooming period.

Unusual color developments continue to emerge from modern breeding programs, with varieties displaying lavender tones, multi-colored effects, and bi-colored patterns. 'First Arrival' offers subtle lavender coloration, while many Itoh varieties feature complex color changes throughout their flowering period, creating dynamic displays that evolve daily.

Seasonal Bloom Classification

Early Season Performance

Early season peonies extend the garden's flowering period by beginning their display when few other perennials have reached their peak. Tree peonies typically lead this early parade, with many varieties blooming in April or early May depending on local climate conditions. Their early flowering provides gardens with spectacular color during the spring transition period.

Among herbaceous types, early varieties include most forms of Paeonia officinalis and certain species like P. tenuifolia and P. mlokosewitschii. These early bloomers often finish their display before the main peony season begins, making them valuable for extending the overall flowering period. 'Early Scout' represents one of the most reliable early herbaceous varieties, consistently blooming ahead of the main season.

Early season varieties often benefit from protection against late spring frosts, which can damage developing buds and flowers. Gardeners in areas prone to late freezes should consider positioning early varieties in locations that receive morning shade or provide temporary protection during critical periods.

Mid-Season Abundance

Mid-season represents peak peony time in most temperate gardens, typically occurring during late May through early June depending on local climate conditions. This period showcases the greatest diversity of varieties and colors, with most P. lactiflora cultivars reaching their peak during this timeframe.

Classic mid-season varieties include many of the most popular garden peonies such as 'Sarah Bernhardt', 'Festiva Maxima', and 'Karl Rosenfield'. These varieties have proven their garden worth over decades of cultivation and represent the standard by which other peonies are often measured. Their reliable performance during the optimal growing period makes them excellent choices for beginning peony growers.

The abundance of mid-season varieties allows gardeners to create spectacular mass displays by selecting multiple varieties that bloom simultaneously. This approach works particularly well in large landscape settings where maximum impact is desired during the peak season.

Late Season Extension

Late season peonies provide valuable extension of the peony flowering period, often continuing into mid or late June when most varieties have finished their display. These varieties often demonstrate increased heat tolerance, allowing them to perform well even as summer temperatures begin to climb.

'Kansas' represents one of the most reliable late season performers, producing deep red flowers well after most varieties have faded. 'Pillow Talk' offers soft pink late season color, while many single varieties naturally tend toward later blooming habits. These late varieties prove particularly valuable in warmer climates where early season varieties may be shortened by rapidly rising temperatures.

Late season varieties often benefit from afternoon shade in warmer climates, which helps extend their flowering period and maintain flower quality during hot weather. Strategic placement can significantly improve the performance of these valuable season extenders.

Fragrance Characteristics

Highly Fragrant Varieties

Peony fragrance represents one of the genus's most appealing characteristics, with the classic "peony scent" being immediately recognizable to most gardeners. This distinctive fragrance combines sweet floral notes with subtle complexity that varies among different varieties and even changes throughout the day.

'Sarah Bernhardt' exemplifies the classic peony fragrance, producing intensely sweet scent that can perfume entire garden areas during peak bloom. 'Festiva Maxima' offers similarly powerful fragrance with slightly different undertones, while 'Eden's Perfume' was specifically bred and selected for exceptional fragrance quality. These highly fragrant varieties work particularly well near seating areas, pathways, or windows where their scent can be fully appreciated.

The intensity of peony fragrance often correlates with temperature and humidity conditions, with warm, humid evenings typically producing the strongest scent. Many gardeners position fragrant varieties strategically to take advantage of prevailing breezes that carry the fragrance throughout their garden spaces.

Fragrance Variations and Considerations

Tree peonies often produce different fragrance profiles than their herbaceous relatives, sometimes featuring spicy or exotic undertones rather than the classic sweet peony scent. These variations add another dimension to garden fragrance planning and can provide interesting contrasts when different types are grown together.

Some modern peony varieties have been bred primarily for visual characteristics, sometimes resulting in reduced fragrance compared to older varieties. Single varieties also tend to produce less intense fragrance than double forms, though there are exceptions to this general pattern. Gardeners prioritizing fragrance should research specific varieties and, when possible, experience them in person before making selections.

Environmental factors significantly influence fragrance production, with plants grown in optimal conditions typically producing stronger scents than stressed plants. Adequate soil moisture, appropriate nutrition, and proper sunlight exposure all contribute to fragrance development, making good growing conditions important for gardeners who value this characteristic.

Climate Adaptation and Hardiness

Cold Hardy Selections

Cold hardiness represents one of the most important selection criteria for gardeners in northern climates, where winter temperatures regularly drop well below freezing. Most herbaceous peonies demonstrate excellent cold tolerance, with many varieties surviving temperatures as low as -40°F when properly established and protected by snow cover.

'Sarah Bernhardt' and 'Festiva Maxima' represent two of the most cold-hardy varieties available, consistently performing well in zones 2 and 3 where many other perennials struggle. Most varieties derived from P. lactiflora show similar cold tolerance, making them excellent choices for northern gardens. P. tenuifolia demonstrates exceptional cold hardiness and can survive in some of the coldest inhabited regions.

Success with cold-hardy peonies requires attention to planting depth and winter protection. Proper planting with crowns positioned 2 inches below soil surface provides essential protection, while mulching after ground freeze helps maintain consistent soil temperatures throughout winter.

Heat Tolerance Considerations

Heat tolerance becomes increasingly important as summers become more intense and gardeners in southern regions seek to grow peonies successfully. While most peonies prefer cool conditions, certain varieties demonstrate improved tolerance for heat and humidity when provided with appropriate growing conditions.

'Festiva Maxima' shows remarkable adaptability, performing well in both very cold and surprisingly warm conditions when given adequate moisture and some afternoon shade. 'Kansas' demonstrates good heat tolerance partly due to its late blooming habit, which allows it to complete flowering before peak summer heat arrives.

Early-blooming varieties often perform better in warm climates because they complete their flowering cycle before intense heat arrives. Single varieties also tend toward better heat tolerance than complex doubles, possibly due to their simpler flower structure and reduced energy requirements for flower development.

Success in warm climates often depends more on providing optimal growing conditions than selecting specific varieties. Afternoon shade, consistent soil moisture, and good air circulation can allow many varieties to succeed in warmer zones than their typical recommendations suggest.

Modern Registration and Recognition

American Peony Society Standards

The American Peony Society serves as the international registration authority for new peony varieties, maintaining comprehensive records and establishing classification standards used worldwide. Their registration system provides essential documentation for new varieties while preserving historical information about older cultivars.

The Society's classification system divides peonies into major categories including herbaceous hybrids, tree peony hybrids, and intersectional hybrids, with detailed subcategories for flower form, color, and other characteristics. This systematic approach ensures consistent identification and communication among growers, researchers, and gardeners worldwide.

Registration requirements include detailed descriptions of flower characteristics, plant habit, blooming period, and parentage when known. This documentation creates valuable databases for researchers and helps prevent confusion among similar varieties.

Award Systems and Recognition

The American Peony Society's award system recognizes exceptional varieties through several categories designed to highlight different aspects of peony excellence. The Gold Medal represents the highest honor, awarded to varieties that demonstrate outstanding garden performance over extended periods and wide geographic ranges.

The Award of Landscape Merit recognizes varieties that provide exceptional garden value through characteristics like reliable blooming, good plant habit, disease resistance, or extended flowering periods. These awards help gardeners identify varieties that will provide superior garden performance beyond just flower beauty.

Exhibition awards recognize varieties that produce exceptional individual flowers suitable for flower shows and competitions. While these varieties may require more intensive care than landscape merit winners, they represent the pinnacle of flower development within the genus.

Practical Selection Strategies

Beginning Gardener Recommendations

New peony growers achieve the greatest success by starting with proven, reliable varieties that demonstrate consistent performance across diverse conditions. 'Sarah Bernhardt', 'Karl Rosenfield', and 'Festiva Maxima' represent three excellent starting varieties that provide different colors while sharing reliable garden performance and relatively simple care requirements.

Single and semi-double flower forms often prove easier for beginners to manage successfully, requiring less staking support and showing better weather resistance than complex double varieties. Mid-season bloomers typically provide the most reliable performance, avoiding the potential frost damage that can affect early varieties and the heat stress that sometimes impacts late bloomers.

Established varieties with long garden histories often prove more forgiving than newer introductions, having demonstrated their adaptability through decades of cultivation under diverse conditions. These time-tested varieties also tend to be more readily available and less expensive than cutting-edge introductions.

Creating Extended Flowering Displays

Gardeners seeking to maximize their peony season should plan combinations that include early, mid-season, and late varieties to extend blooming from early May through late June. Tree peonies provide the earliest flowers, followed by early herbaceous varieties, then the main mid-season display, concluding with late varieties and Itoh hybrids that often continue blooming into July.

Itoh varieties offer particular value for season extension due to their prolonged individual flowering periods, often blooming for three to four weeks compared to the one to two weeks typical of herbaceous varieties. Strategic placement of these longer-blooming varieties can provide continuous color throughout the extended season.

The integration of different peony types creates opportunities for sophisticated seasonal progressions, with tree peonies providing dramatic early impact, herbaceous varieties contributing peak season abundance, and Itoh varieties extending the display with their unique colors and extended blooming periods.

Specialized Garden Applications

Cut flower gardens benefit from varieties selected specifically for their post-harvest performance, stem strength, and flower longevity. Double varieties typically provide the fullest flowers for arrangements, while fragrant varieties like 'Sarah Bernhardt' and 'Eden's Perfume' add sensory appeal to indoor displays. Strong-stemmed varieties such as 'Festiva Maxima' and 'Karl Rosenfield' reduce the need for artificial support in arrangements.

Low-maintenance landscapes favor single varieties and species selections that require minimal intervention while providing reliable performance. These varieties rarely need staking, show good disease resistance, and often demonstrate superior longevity compared to more complex cultivars. Their simpler flower forms also provide better wildlife value through accessible pollen and nectar resources.

Formal garden settings often benefit from the structured appearance of bomb-type varieties and uniform double forms that provide consistent visual impact. These varieties work well in geometric plantings and formal borders where regularity and predictability support the overall design concept.

Understanding these diverse classification systems and selection strategies enables gardeners to make informed choices that will provide decades of peony enjoyment. Whether seeking simple beauty, extended seasons, or specialized applications, the rich diversity within the peony genus offers options for virtually every garden situation and personal preference.