Black-eyed Susans provide color in summer gardens
Close your eyes and imagine a perennial border in the height of summer. What colors do you see? What flowers are blooming? Surely you see a sunny bunch of black-eyed Susans somewhere in that garden.
The black-eyed Susans in your imaginary garden are probably the most popular of rudbeckias, "Goldsturm." It was named Perennial of the Year back in 1999. Its deep yellow flowers bloom brilliantly over dark green foliage from July to September and grows best in full sun in rich, moisture-retentive soil.
Goldsturm may be one of the most widely grown rudbeckias, but there are many other varieties. From small to tall, there is a rudbeckia for your garden.
Beginning with the smallest, dwarf black-eyed Susan - Viette's Little Suzy - tops out at just 15 inches tall. It features golden yellow daisylike flowers that bloom from midsummer to fall. An added bonus: the foliage turns mahogany in fall. Place this charmer with Sedum Autumn Joy for a delightful combination. Add a small ornamental grass like dwarf fountain grass and disprove the saying "three's a crowd."
The native orange coneflower, or Rudbeckia fulgida var. fulgida, sports smaller flowers than Goldsturm, but blooms longer. Deadheading will keep it going into October, but leave some seed heads for the goldfinches - they love them!
There are many mid-sized rudbeckias. Goldquelle, commonly referred to as cut leaf coneflower, has double lemon-yellow flowers beginning in July over finely cut foliage. This clump former grows from 24 to 30 inches tall. Deadheading spent flowers may reward you with additional flowers in the fall. Plant this variety in full sun for stems strong enough to support the large, heavy flowers.
Sweet black-eyed Susan, or Rudbeckia subtomentosa, is a native prairie plant. Their brown-coned, yellow-petaled flowers reach 2- to 3-feet tall and bloom in July and August. This perennial commonly found in meadows brings butterflies, bees and beneficial insects into your garden. Plant this with another butterfly magnet, Aster Monch. The clear lavender-blue blooms of the aster contrast nicely with those of the rudbeckia and add color to the late summer garden when other perennials are winding down. Be sure to plant these in moist, well-drained organic soil.
And now to the big guys - those rudbeckias that contribute flowers at great heights in your garden beds and borders.
The flowers of great coneflower, botanically known as Rudbeckia maxima, may look similar to other rudbeckias, but the foliage has a completely different appearance. Worth growing for the foliage alone, its huge powder-blue basal leaves offer coarse texture in the garden.
While the paddle-like foliage tops out at 2 to 3 feet, its large, black-centered, deep golden flowers skyrocket to 6 feet in June. After the petals fall, attractive seed heads prolong its pleasing presence. This native plant prefers a site in full sun and moist, well-drained soil.
Named for the retired nurseryman who found it, Rudbeckia Henry Eilers is a spectacular variety. Five- to 6-foot stems ascend from basal foliage in June and burst into bloom in mid to late summer. Its unique flowers feature finely quilled, true yellow petals radiating from small brown centers. Partner it with Joe-Pye weed and ornamental grasses - gorgeous!
Another garden Goliath is Rudbeckia Herbstonne. Commonly called autumn sun coneflower, this towering rudbeckia forms a massive clump that grows 3- to 6-feet tall and 3- to 4-feet wide. The single, sulfur yellow flowers bloom from July to September attracting butterflies and providing a flowering backdrop for other perennials. Plant it in full sun in a site with good drainage and protection from strong winds. Staking may be necessary if it is planted in too much shade or in an open area.
The care of rudbeckias couldn't be much easier when they are planted in the proper place. Most prefer full sun, although some will tolerate light shade. They thrive when planted in a moist site, but are relatively drought tolerant. They spread by strong, fibrous roots and also self-sow creating lovely drifts.
Fertilization is rarely necessary and not recommended for taller varieties. Deadheading will prolong blooming and may generate a second flush of flowers later in the season, but leave some seed heads on plants for the birds to feast on.
Rudbeckias are also among the best perennials for cut flowers. They do, however, require proper conditioning. Cut stems and put them in water immediately. Next, place the bottom inch of each stem in boiling water for a few seconds and then immerse the entire stem in cool water for several hours. Following these steps will ensure a long vase-life for the sunny blooms.
Whether tall or small, rudbeckias are a mainstay in the summer perennial border. They are hardy, long-lived, bothered by few insects and diseases, and need little care. You can depend on them to provide bright, long-lasting color for weeks at a time when our gardens need it most.
•Diana Stoll is a horticulturist and the retail manager of The Planter's Palette, 28W571 Roosevelt Road, Winfield. Call (630) 293-1040 or visit planterspalette.com.