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Paeonia 'Bartzella'
Bartzella Peony
Hybrid of horticultural origin (Itoh intersectional hybrid)
Overview
'Bartzella' is an Itoh hybrid (intersectional) peony reaching 30-36 inches (76-91 cm) tall and 36-42 inches (91-106 cm) wide. Stems are herbaceous and die back to ground each fall, but are stiffer than typical Paeonia lactiflora stems and often need no staking. Compound leaves are 8-12 inches (20-30 cm) long with 9-12 deeply lobed leaflets each 3-5 inches (7.5-13 cm) long, dark green through the growing season, turning yellow-green to bronze before frost. Semi-double to double flowers, 6-8 inches (15-20 cm) across, are sulfur-yellow with red-purple flares at the petal bases; mature plants produce 30-50 flowers per season. Fragrance light to moderate, lemony. Flowers open over a 3-4 week period in late spring; individual flowers last 5-7 days. Hardy to zone 4 (-30°F / -34°C); cold tolerance is intermediate between herbaceous and tree peony parents. Stems do not retain woody structure over winter as in tree peonies; plants emerge from crown buds in spring. Slower to establish than Paeonia lactiflora: full flowering develops in 4-5 years rather than 2-3. Botrytis blight and powdery mildew develop in humid conditions with poor air circulation; cosmetic only on established plants.
Native Range
A horticultural hybrid (Itoh hybrid) developed by Roger Anderson in Wisconsin and registered in 1986; the cross is between herbaceous Paeonia lactiflora hybrids and tree peony Paeonia x suffruticosa or Paeonia delavayi hybrids. The parent species are native to East Asia (P. lactiflora from northern China, Mongolia, and Siberia; tree peonies from central and southwestern China).Suggested Uses
Planted in perennial borders, cottage gardens, and as cut-flower specimens, spaced 3-4 feet (90-120 cm) apart in zones 4-7. Used in mass plantings of 3-5 plants for a sustained yellow bloom period in late spring. Crown placement requires permanent siting; mature plants recover slowly from transplanting and may not flower for 2-3 years afterward.How to Identify
Appearance
Size & Dimensions
Height2'6" - 3'
Width/Spread3' - 3'6"
Reaches mature size in approximately 5 years
Bloom Information
Mid-May through mid-June in zones 4-7, with peak bloom in late May. Individual flowers last 5-7 days; total bloom period extends 3-4 weeks because new buds open sequentially. Bloom occurs 1-2 weeks later in zones 4-5 than in zones 6-7. Cool spring temperatures below 60°F (16°C) extend the bloom period by 5-7 days.Detailed Descriptions
Flower Description
sulfur yellow with red-purple flaresFoliage Description
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
Water deeply once a week during the first two growing seasons; established plants tolerate 1-2 weeks without rain. Set crown buds 1-2 inches (2.5-5 cm) below the soil surface; deeper planting reduces or eliminates flowering. Apply low-nitrogen fertilizer in early spring; high-nitrogen formulations produce leafy growth at the expense of flowers. Botrytis blight develops in cool wet springs; remove and destroy affected stems. Mature crowns flower for 50+ years without division. Container culture rarely succeeds; herbaceous peonies require a winter chill period and decline in pots smaller than 15 gallons (57 L).Pruning
Cut all stems to 2-3 inches (5-7.5 cm) above ground in late fall after first hard frost; remove and destroy debris to reduce overwintering Botrytis spores. Deadhead spent flowers at the petiole; cutting into the leaf stem reduces next-year flowering. Crown division is poorly tolerated; if needed, divide in early fall every 8-10 years rather than the 3-4 years typical of herbaceous peonies. Leave foliage intact through summer; early removal weakens crown buds and reduces next season's bloom.Pruning Schedule
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fallwinter