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© MP Zhou, some rights reserved (CC-BY-NC) · iNaturalist
At a Glance
Typeshrub
Habitupright-spreading
Foliageevergreen
Height48-120 inches (120-300 cm)
Width48-96 inches (120-240 cm)
Maturity3 years
Growing Zones
USDA Hardiness Zones
9 - 11These zones indicate the coldest temperatures this plant can typically survive.
What's my zone? →Frost Tolerancetender
Key Features
Maintenancelow
Overview
Senna bicapsularis is the butterfly bush senna (Christmas senna), growing 48-120 inches (120-300 cm) tall and 48-96 inches (120-240 cm) wide. Bright yellow 5-petaled flowers 1 inch (2.5 cm) in terminal and axillary racemes 4-8 inches (10-20 cm) from fall through winter — the cool-season bloom period gives the common name 'Christmas senna.' Blooms when few other shrubs flower, filling a seasonal gap. Butterfly-attracting: sulphur butterflies (Phoebis spp.) use Senna species as larval host plants. Medium green pinnately compound leaves with 3-4 pairs of oval leaflets 1-2 inches (2.5-5 cm). Cylindrical seed pods 3-5 inches (7-13 cm). In the legume family (Fabaceae). Native to the Caribbean, Central America, and northern South America. Classified as invasive in Hawaii, Florida, and parts of Australia and Africa, where it self-seeds aggressively into disturbed areas. All parts contain anthraquinones — a purgative toxic to dogs, cats, and humans if ingested. Drought-tolerant once established. Adapts to alkaline soils (pH to 8.0). Full sun (6+ hours). Fast-growing — 24-48 inches (60-120 cm) per year. Deer-resistant. Frost-tender: foliage damage at 30°F (-1°C). Growth rate is fast. Containers of 5+ gallons (20+ liters). Zones 9-11.
Native Range
Native to the Caribbean, Central America, and northern South America. Invasive in Hawaii, Florida, parts of Australia and Africa.Suggested Uses
Grown in the ground in zones 9-11 or in containers of 5+ gallons (20+ liters). Full sun. The cool-season bloom fills a gap when few other shrubs flower. Butterfly host plant. Invasiveness regulations vary by region. All parts toxic. Deer-resistant.How to Identify
Appearance
Size & Dimensions
Height4' - 10'
Width/Spread4' - 8'
Reaches mature size in approximately 3 years
Bloom Information
Fall through winter (October-January), lasting 8-10 weeks. Bright yellow flowers in racemes. Blooms during the cool season when few other shrubs flower. Cylindrical seed pods follow.Detailed Descriptions
Flower Description
Bright yellow, in terminal and axillary racemesFoliage Description
Medium green, pinnately compound with 3-4 pairs of oval leafletsGrowing Conditions
Sun Requirements
Requires 6-10 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
Full sun (6+ hours). Drought-tolerant once established. Adapts to alkaline soils. Invasive in some tropical regions — local regulations vary by state and country. Butterfly host plant. All parts toxic (anthraquinones). Fast-growing. Deer-resistant. Frost-tender at 30°F (-1°C). Zones 9-11.Pruning
Hard pruning by one-third to one-half in late winter after flowering maintains a compact form. The fast growth rate calls for annual pruning. Seed pods are removed to reduce self-seeding (invasive in some regions).Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
winter
Maintenance Level
lowContainer Growing
✓ Suitable for container growing
Minimum container size: 5 gallons