How to Grow Rudbeckia
Commemorating Olaf Rudbeck (16601740) Swedish professor of botany and counselor of Linnaeus (Compositae). Cone flower. A genus of about 40 herbaceous plants, mostly perennial and hardy, natives of North America, related to Echinacea. The flowers are showy, daisy-like, often with drooping petals and conspicuous conical centers. Most of them are excellent herbaceous border plants and are valuable for late summer effect in the garden.
Species cultivated R. bicolor, 1-2 feet, half-hardy annual, yellow, ray petals yellow, sometimes with purplish bases, disk purplish, conical, July; var. superba, flowers 2 inches across, petals brown on the under-sides; cultivars include ‘Golden Flame’, golden-yellow; ‘Kelvedon Star’, 3 feet, golden-yellow with mahogany red zone; ‘My Joy’ (Mon Plaisir’), dwarf habit, flowers golden-yellow. R. fulgida deamii (syn. R. deamii), 2-3 feet, a somewhat hairy plant of erect habit; flowers deep yellow, inches across with purple‑black centres, freely produced, July to September; var. speciosa (syns. R. speciosa, R. newmanii), 2 feet, black-eyed Susan, similar but of laxer habit, an old favourite;’Goldsturm’, 2 feet, an excellent larger-flowered form of stiffer habit and less hairy, August-September, a good garden plant. `Goldquelle’, 2-3 feet, a newer hybrid of erect growth with lemon-yellow flowers three or more inches across, August-September. ‘Herbstsonne’ (R. laciniata x R. nitida), 6-8 feet, a tall, erect-growing plant with large, deeply-cut leaves and golden-yellow flowers with green cones, September. R. hirta hybrida, 2 feet, usually grown from seed as an annual or biennial, a bristly-hairy plant, striking flowers in shades of gold, orange and mahogany, summer. R. laciniata ‘Golden Glow’, 6 feet, deeply-lobed green leaves and fully double yellow flowers, 3 inches across, August to September. R. maxima, 4-6 feet, a rather rare and very ornamental species with large handsome glaucous leaves and rich yellow flowers with dark centres, August-September, Texas. R. purpurea see Echinacea purpurea, R. tetra ‘Gloriosa’, Gloriosa daisy, 2-3 feet, half hardy annual, flowers to 7 inches across, colours various including yellow, mahogany-red, bronze, and bicolors ; double-flowered forms are also offered.
Cultivation Most rudbeckias are easy to grow. A sunny or semi-shaded site with good but well-drained loamy soil is preferable though the plants grow well on chalk. Some of the taller species and their varieties prefer moister soils and are particularly useful when grown in groups among shrubs or in the wild garden where they provide an early autumn display. Hybrids or cultivars have now largely replaced many of the species in general cultivation. The perennial sorts do best if they are divided and replanted every third or fourth year. R. hirta is best treated as an annual and succeeds in a sunny position in well-drained soil. Seeds of the half-hardy annual kinds should be sown under glass in gentle heat in early spring. After they have been hardened off the seedlings should be planted out 9 inches apart in late May or early June, where they are to flower. R. maxima is rather slow to become established and requires a moist soil. Propagation of the perennials is easily effected by seed or by division in the spring.