Scientific: Senna artemisioides subsp. artemisioides (Synonyms: Cassia artemisioides, Cassia artemisiifolia, Cassia artemisioides var. eremophila, Cassia glaucescens)
Common: feathery senna (formerly called feathery cassia)
Family: Fabaceae (Leguminosae)
Origin: Senna artemisioides is native to the entire Australian continent; whereas, the subspecies are localized therein. The subspecies artemisioides occurs throughout the continent, but is mostly found in central Australia.
Pronounciation: SIN-na ar-te-mi-see-OYE-deez ar-te-mi-see-OYE-deez
Hardiness zones
Sunset 8, 9, 12-16, 18-23
USDA 9-11
Landscape Use: Accent, large informal hedge, good background or screen planting for dry landscapes, avoid use as formal hedge.
Form & Character: Lacey, open shrub, rounded to globose, wispy desert effect, Australian.
Growth Habit: Large evergreen, woody, broadleaf (narrow leaflets) perennial shrub, vigorously upright and billowing to 15 feet with nearly equal spread, wood brittle.
Foliage/Texture: Gray, pinnately compound, 10 narrow, linear leaflets per leaf; fine texture.
Flowers & Fruits: Sulfur yellow pea shaped flower, fragrant like a strong men's musk cologne during early spring on old wood. Flower buds are initiated in August but remain latent until early spring. Fruits are an ugly green then brown bean pod, spring and early summer.
Seasonal Color: Brilliant sulfur yellow in early spring
Temperature: Cold tolerant to 22oF.
Light: Full sun only.
Soil: Feathery senna must have a well-drained soil to sustain landscape performance.
Watering: Deep infrequent irrigations. Overwatering will promote excessive growth.
Pruning: Prune as necessary only after flowering in late April to early May because fruit pods are unsightly and should be removed. Severe renewal pruning after flowering will rejuvenate, but make sure to leave at least some foliage when doing this otherwise this shrub will not recover. Frequent shearing of feathery senna will negatively impact spring floral displays as this plant sets flower buds in August for flowering the following February.
Propagation: Seed, hot water soak or acid scarify. Feathery senna readily reseeds in the urban landscape.
Disease and Pests: Root rot in poorly drained soils.
Additional comments: This is a large shrub so plan to use it in spaces large enough to accommodate its mature size. Around the Phoenix and Tucson area, this plant is so often misplaced, planted in inappropriately small spaces, and poorly maintained in the landscape that its true winter/spring accent in the landscape is compromised by 'Hort clods' in favor of "bowling balls and beer kegs". Generally looks deceptively sparse in a nursery container.
