In the Garden:
Prairie Sun's 5-inch blooms have green centers surrounded by petals that fade from deep gold near the center to lemon yellow at the tips.
Beautiful Black-Eyed Susans
What's not to like about black-eyed Susans? They're hardy and reliable, with abundant golden yellow blooms that brighten the summer garden. Gathered by the armful, the cut flowers make a festive -- and long-lasting -- summer bouquet. But these aren't the reasons I first fell in love with black-eyed Susans: It was their name that caught my attention as a young child. I was sure they were named after me (but some silly person spelled Suzanne wrong).
The botanical name, Rudbeckia, is less colorful but more accurate when it comes to distinguishing among the many species and varieties of plants commonly called black-eyed Susans. Other common names include brown-eyed Susan, gloriosa daisy, and oxeye daisy.
There are about 25 species of rudbeckia, including annual, biennial, and perennial varieties. They're found across the country, with every region having at least one native species except the desert southwest. As a group, they are rated as hardy in USDA Hardiness Zones 3 through 10, although individual species and varieties may have more limited ranges. Rudbeckias, like many native flowers, attract birds and butterflies.
In general, rudbeckia flowers have yellow petals with dark centers. The plants prefer full sun, and although established plants are relatively drought tolerant, they thrive with regular watering. Rudbeckias are vigorous self-sowers and left on their own the offspring may overwhelm other garden plants.
Annual or Perennial?
The line between annual and perennial blurs with rudbeckias. Some types are short-lived perennials, but because they bloom the first year from seed they're grown as annuals. Others are true perennials. And because they reproduce readily from seed, even the short-lived types can form perennial stands when allow to self-sow.
Rudbeckia hirta and R fulgida are the two species most readily available to gardeners. Varieties of R. hirta tend to be short-lived and are often grown as annuals. Many of the most common rudbeckias fall into this category, including 'Prairie Sun' and 'Indian Summer'. Varieties of R. fulgida are true perennials.
Rudbeckia hirta Varieties
There seems to be some confusion about whether certain Rudbeckia hirta varieties are annuals, biennials, or short-lived perennials. Different sources classify varieties differently. However, most sources agree that the plants flower the first year if sown in early spring and readily self-sow. If your plants overwinter and rebloom, consider it a bonus. All the varieties described below make excellent cut flowers except the dwarf 'Toto'.
'Prairie Sun' -- This variety was a 2003 All-America Selection and a Gold Medal winner in the 2003 Fleuroselect trials across Europe. Instead of the usual brown eye, Prairie Sun's 5-inch blooms have green centers surrounded by petals that fade from deep gold toward the center to lemon yellow at the tips. This variety grows to a height of 30 inches. (For more information on All-America Selections, visit http://www.all-americaselections.org; on Fleuroselect, visit http://www.fleuroselect.com/)
'Indian Summer' -- The huge, sunflower-like blooms on this variety are bright yellow with dark brown centers. Larger than most R. hirta varieties, Indian Summer grows up to 36 inches tall. It was named the 2000 Fresh Cut Flower of the Year by the Association of Specialty Cut Flower Growers (http://www.ascfg.org/) and was a 1995 All-America Selection.
'Cherokee Sunset' -- A 2002 All-America Selection, Cherokee Sunset's 3- to 4 1/2-inch flowers may be yellow, orange, mahogany, and bronze, or a blend of colors. Grows to a height of 24 to 30 inches.
'Gloriosa' and 'Double Gloriosa' - These cultivars have very showy flowers up to 6" across, with yellow, gold, or reddish bronze rays. Plants grow to a height of about 24 inches.
'Toto' - The flowers on this dwarf variety have full, rounded petals. Toto grows to a height of about 12 inches, and its tidy, compact habit make it good for border edgings and container plantings.
Other Rudbeckia Species
Rudbeckia fulgida is native to Missouri, where it thrives in a variety of habitats. The species grows to a height of about 36" and has a long bloom period, flowering from mid-summer until fall. A popular cultivar is Goldsturm (R. fulgida var. sullivantii 'Goldsturm'), which was named the 1999 Perennial Plant of the Year. Goldsturm is smaller than the species, growing to a height of 18 to 30 inches, and is notable for its abundant flowers. (For more information on the Perennial Plant Association, visit http://www.perennialplant.org) Another R. fulgida variety, Viette's Little Suzy, is smaller still, reaching only 10 to 15 inches in height.
Rudbeckia triloba, commonly called three-lobed or thin-leaved coneflower, is native to the prairies. More dainty in appearance than its cousins, the plant has an airy, open form and is completely covered with small yellow blooms with black button centers from July to October cousins. The tall (up to 48-inch) stems may need staking. Rated hardy in USDA Zones 5 through 7, R. triloba is considered a short-lived perennial, but it readily self-sows.
Rudbeckia laciniata is rated hardy in USDA Zones 3 to 9 and requires moister soils than other species. Athough it can grow up to 9 feet tall in the wild, it more commonly reaches a height of 3 to 4 feet. The daisy-like flowers have drooping petals and domed green centers. Native to much of the US, the plant's common names include cutleaf coneflower, green-headed coneflower, and tall coneflower.
Rudbeckia maxima has unique, waxy blue-green foliage instead of the usual coarse, hairy leaves of other rudbeckias. Flowers have droopy yellow petals surrounding a tall brown cone, and flower stalks can reach a height of 7 feet or more. One of its common names, swamp coneflower, alludes to its preference for damp soils. Another common name is cabbage leaf coneflower. Native to warm, moist Southern woodlands, it is hardy in USDA Zones 5 through 9.
Two rudbeckia varieties, Black Beauty and Green Wizard (R. occidentalis 'Black Beauty' and R. occidentalis 'Green Wizard') are unusual in that they lack the yellow petals of most rudbeckias. Instead, the black center cone is surrounded by the bright green sepals. They make a striking addition to both the garden and to cut flower arrangements.
Planted in full sun and reasonably moist soil, rudbeckias are remarkably carefree. Provide supplemental water the first season to help young plants get established. Rudbeckias are bothered by few insect and disease pests and need little or no supplemental fertilizing, especially if you amend the soil with compost before planting. Deadheading prolongs the bloom time, but be sure to leave some seedheads on the plants to attract birds and provide winter interest.
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