- Name: Silver Cassia - Other Common Names: Silver Leaf Cassia / Silvery Cassia / Senna - Scientific Name: Cassia Artemisioides / Senna Artemisioides - Color: Yellow - Plant Seeds: Outdoors After Frost / Indoors Weeks Before Last Frost - Bloom Time: All Season (Repeat Bloomer) - Hardiness Zone: 8 - 11 - Plant Height: 48 - 60” - Plant Spacing: 36 - 48” - Light Requirements: Sun - Part Shade - Soil & Water Preferences: Average - Dry - Quantity: 25 Seeds - Other: This Cassia Is An Evergreen Shrub With Silvery Blue-Green Sprays Of Foliage. It Has Fragrant Flowers That Attract Bees, Birds, & Butterflies. This Australian Native Grows Quickly And Is Tolerant Of All Soil Types And Drought.