Paeonia 'Bartzella'
Bartzella Itoh Peony
Overview
Paeonia 'Bartzella' is an Itoh-group intersectional peony hybrid reaching 24-36 inches (60-90 cm) tall and 36-48 inches (90-120 cm) wide at maturity. The Itoh designation indicates a sterile hybrid between herbaceous peonies (typically P. lactiflora) and tree peonies (typically P. × suffruticosa or P. delavayi); the resulting plant combines the underground crown of herbaceous parents with deeply lobed, woody-textured foliage from tree peonies. Stems die back to a basal woody crown each winter. Compound leaves carry deeply lobed leaflets 2-4 inches (5-10 cm) long, glossy dark green from spring through late autumn, sometimes turning butterscotch-yellow before frost. Semi-double to double flowers measure 6-8 inches (15-20 cm) across, with 50-60 lemon-yellow petals surrounding a central red flare. Each plant produces 30-50 flowers at maturity (5-7 years), with multiple buds per stem extending bloom over 2-3 weeks. A lemon-spice fragrance is detectable within 12 inches (30 cm) of an open flower. Plants are sterile and produce no viable seed; propagation occurs by division of the crown.
Native Range
Itoh peonies are sterile garden hybrids first produced by Japanese horticulturist Toichi Itoh in the 1940s by crossing herbaceous Paeonia lactiflora with tree peony P. × suffruticosa cultivars. Wild ancestors of the herbaceous parent are native to East Asia (China, Tibet, Korea, Mongolia) in mountain meadows and forest margins at 5,500-13,000 feet (1,700-4,000 m) elevation. P. 'Bartzella' was registered by Roger Anderson of Wisconsin in 1986.Suggested Uses
Planted in mixed perennial borders, peony beds, and as a long-lived mid-border specimen, spaced 36-48 inches (90-120 cm) apart. Cut for the vase at the soft-bud or first-color stage for 7-10 day vase life. Container culture is possible in pots 15 gallons (57 L) or larger but flowers less profusely than in-ground plants and requires daily watering during summer.How to Identify
Appearance
Size & Dimensions
Height2' - 3'
Width/Spread3' - 4'
Colors
Bloom Information
Late May through mid-June in zones 4-7 with peak bloom over 10-14 days; flowering ends earlier in zones 8-9, typically by late May. Each stem carries 1-3 flowers, with later side buds extending the show 2-3 weeks beyond the first opening. Bloom volume increases from 5-10 flowers in year three to 30-50 flowers at year five and beyond. Cool spring weather extends individual flower life by 3-4 days.
Detailed Descriptions
Flower Description
Lemon-yellow double flowers with red central flareFoliage Description
Glossy dark greenGrowing Conditions
Sun Requirements
Requires 6-8 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Plant in fall (September-October) at 36-48 inches (90-120 cm) spacing with the topmost eyes 1-2 inches (2.5-5 cm) below the soil surface; deeper planting reduces flowering for several years. Water weekly through the first growing season; established plants tolerate 3-4 weeks without rain in zones 4-7. Plants are heavy feeders; apply 2-3 inches (5-8 cm) of compost in spring and a low-nitrogen balanced fertilizer after bloom. Botrytis blight occurs in cool, wet springs as gray fuzzy rot on buds and stems; cut and remove infected tissue at first appearance. Itoh peonies are not divided as often as herbaceous types; if division is needed, lift the crown in early September and cut sections with 3-5 eyes each. Mature plants live 50 years or more undisturbed.Pruning
Cut stems to 2 inches (5 cm) above the crown after the first hard frost or in early spring before new growth emerges; the woody crown is left intact. 'Bartzella' is sterile and does not produce seed, so deadheading is not needed for seed prevention; spent flowers may be cut for tidiness. Staking is not required at this cultivar's stem strength.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
fallearly spring
Container Growing
Minimum container size: 15 gallons