Rudbeckia

Fundamental Facts

HARDINESS: Zones 3 to 10
PREFERRED SOIL pH: Neutral to slightly acid
PREFERRED SOIL TYPE: Average to moist, well-drained
PREFERRED LIGHT: Sun
ATTRIBUTES: Prolific yellow daisies on robust plants; for meadows, beds
FAVORITES: 'Goldsturm', 'Gold-quelle'; R. laciniata; R. triloba
QUIRKS: Sometimes short-lived, but renews itself by self-seeding readily
GOOD NEIGHBORS: Joe Pye weed, ornamental grasses, purple cone-flower, Russian sage
SEASON OF INTEREST: Early summer to fall
WHERE IT GROWS BEST: In sun and moist, well-drained soil
POTENTIAL PROBLEMS: Powdery mildew in late summer; aphids
RENEWING PLANTS: Individual plants last 2-3 years; divide when flowering diminishes
CRITTER RESISTANCE: Good except for deer (occasionally)
SOURCE: Bedding plants, division
DIMENSIONS: 2-3 ft (0.6-1 m) tall or more, 2-3 ft (0.6-1 m) wide; varies by species

Rudbeckia in the Landscape

Best known as black-eyed Susans, rudbeckias reward minimal effort with a 3-month outpouring of flowers that few other perennials can match. Turn rudbeckias loose in a sunny meadow, where they'll supply a splash of bright yellow all summer, or plant a mass alongside a wooden fence for a casual, colorful display.

Rudbeckias appearance is neat enough to be included in a perennial border, preferably in a spot where it can grow tall and full. Unlike some daisy relatives, rudbeckias have sturdy stems. No matter how many flowers they generate, the plants never flop or need staking. The stiff stems make rudbeckias ideal for arrangements, especially if you cut stems early in the morning, before they've been stressed by sun.

Selecting Susans

Rudbeckias are native to the North American Midwest and South, and some of the best cultivars are crosses of species that have stood the test of time.The 2 ft (0.6 m) tall 'Goldsturm' cultivar, which is propagated by division, is one of the best for longevity and all-around garden performance.

There are numerous other rudbeckias to try from either plants or seed. Cudeaf coneflowers (Rudbeckia laciniata) make a stunning show in late summer, producing a riot of yellow flowers with green centers atop 6 ft (1.8 m) tall plants. For double flowers, go for the shaggy, many-petaled 'Goldquelle'. Three-lobed coneflower (R. triloba) can tolerate some shade and spews out dozens of button-sized, black-eyed yellow daisies on 3 ft (1 m) tall plants.

When they are pleased with their site, rudbeckias develop into vigorous clumps. But they also have a talent for adapting their growth pattern to the climate in which they are grown. In hot, humid climates, plants may flourish for only two years or so. during which time they shed seeds that sprout in either fall or early spring. So, even if a parent perishes unexpectedly, you should find plenty of adoptable volunteers that are easily dug and moved to where you want them to grow and flower.

Growing Rudbeckia

Grow rudbeckias in well-drained, moderately fertile soil to get them off to a strong start. Set out plants in early spring, or in the fall in Zones 7 to 9. If the site is naturally moist, you'll need to water less. If you want to increase your stock, dig and divide mature plants in the spring, replanting them at the same depth at which they previously grew.

Late in the season you may see whitish patches of powdery mildew on the leaves. By this time the flowers are on the wane, and it's fine to cut the plants back to 6 in (15.2 cm) from the ground to nip this unsightly, but never fatal, fungal disease in the bud. While most pests shun rudbeckias, you may spot sap-sucking aphids on tender new growth. Knock them off with a strong stream of water, or apply insecticidal soap according to label directions. If food is scarce, deer may browse the plants. Tuck bars of deodorant-formula bath soap among plantings to repel them, or apply a commercial repellent according to package directions.