Introduction

While other trees are preparing for winter, butterfly bush is just waking up. This sprawling, semi-evergreen shrub, reaching a height of 8 to 10 feet with an equal spread, produces blossoms in fall that resemble golden butterflies. Bright yellow flowers appear at a time of year when little else is in bloom. This plant has a place in any sunny landscape.

General Information

Scientific name: Cassia bicapsularis

Pronunciation: KASS-ee-uh bye-kap-soo-LAIR-iss

Common name(s): Butterfly bush

Family: Leguminosae

USDA hardiness zones: 9A through 11 (Fig. 2)

Origin: not native to North America

Invasive potential: little invasive potential

Uses: specimen; container or planter; deck or patio; highway median

Availability: not native to North America

Description

Height: 8 to 12 feet

Spread: 8 to 10 feet

Crown uniformity: irregular

Crown shape: vase, round

Crown density: open

Growth rate: moderate

Texture: fine

Foliage

Leaf arrangement: alternate (Fig. 3)

Leaf type: even-pinnately compound

Leaf margin: entire

Leaf shape: obovate, ovate

Leaf venation: pinnate

Leaf type and persistence: semi-evergreen

Leaf blade length: less than 2 inches

Leaf color: green

Fall color: no color change

Fall characteristic: not showy

Flower

Flower color: yellow

Flower characteristics: very showy

Fruit

Fruit shape: pod or pod-like

Fruit length: 1 to 3 inches, 3 to 6 inches

Fruit covering: dry or hard

Fruit color: brown

Fruit characteristics: does not attract wildlife; not showy; fruit/leaves not a litter problem

Trunk and Branches

Trunk/bark/branches: branches droop; not showy; typically multi-trunked; thorns

Pruning requirement: needed for strong structure

Breakage: susceptible to breakage

Current year twig color: brown, green

Current year twig thickness: medium

Wood specific gravity: unknown

Culture

Light requirement: full sun, partial sun, or partial shade

Soil tolerances: clay; sand; loam; slightly alkaline; acidic; well-drained

Drought tolerance: moderate

Aerosol salt tolerance: moderate

Other

Roots: not a problem

Winter interest: no

Outstanding tree: no

Ozone sensitivity: unknown

Verticillium wilt susceptibility: unknown

Pest resistance: resistant to pests/diseases

Use and Management

When knocked down by frost, the stems should be cut off at ground level and vigorous sprouts will emerge in spring. Butterfly bush benefits from frequent pinching of the young shoot tips during the growing season up to the beginning of September; this encourages branching and increases the number of flowers. Appropriate training can produce a very small specimen tree which looks nice growing in a low ground cover. Trees often fall over and will require staking to hold them upright. For this reason, it is easiest to place it in a shrub border among other shrubs that will help hold it erect. Well worth the effort to stake a specimen tree, if needed, since the tree is simply stunning in flower.

Tolerant of many soil conditions, butterfly bush needs full sun for best growth and flowering, and needs little care once established. Plant it and forget about it, except for occasional watering during drought. A good plant for highway median or roadside specimen or cluster planting.

Propagation is by seed or cuttings.

Pests

Foliage and flower buds are often eaten by caterpillars in the fall, but these can be easily picked off by hand. Cassia is otherwise seldom plagued by insect pests or diseases. Damaged or stressed cassia can be infested with trunk borers.

Diseases

No diseases are of major concern.