Black-Eyed Susan, Gloriosa Daisy
Scientific Name: Rudbeckia hirta L.
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Rudbeckia hirta 'Becky Mix', 12 inches tall (30 cm)
Recommended Temperature Zone:|
sunset: All zones
Frost Tolerance: Hardy in Phoenix
Heat Tolerance: Partial sun in summer in Phoenix, keep well watered
Sun Exposure: Full sun
Origin: Northern America
Growth Habits: Biennial, sometimes grown as annual, 3 feet tall (1 m)
Watering Needs: Fairly drought tolerant, but they perform best with regular watering
Rudbeckia hirta, the black-eyed Susan, is a biennial forb about 3 feet tall (1 m) with yellow ray flowers and dark brown spherical centers. After germination, the seedling grows into a rosette with oblong leaves. Sometimes flower stalks will appear in the first summer, but typically black-eyed Susan blooms from June to September of the second year. After flowering and seed maturation, the plants die.
Black-eyed Susan is naturalized in most of the states east of Kansas and the bordering areas of Canada. It is adapted throughout the Northeast on soils with a drainage classification range from well-drained to somewhat poorly drained. It will perform acceptably on droughty soils during years with average or above rainfall, but best growth is achieved on sandy, well drained sites. It is winter hardy in areas where low temperatures are between -30 ° and -20 °F.
The Black-Eyed Susan blooms from July to October. Flowering is more profuse when the faded blossoms are removed. The flowers are useful for cutting.
The seed is very small (1,746,000 per pound) and black, about 2 mm long and 0.5 mm in diameter. Rudbeckia seed may be planted directly in place, but seeds started indoors germinate more quickly. The seed should be barely covered. They germinate in 5 to 10 days at 70 to 75° F (21 to 24° C).