Several weeks ago I mentioned that the National Garden Bureau picks one vegetable and one flower every year to be showcased.
Honors are bestowed on these horticultural notables "because they are easy to grow from seed, widely adaptable, genetically diverse and versatile." This year's flower is Rudbeckia, also known as black-eyed Susans, coneflowers or gloriosa daisies.
Rudbeckia started out as a wildflower native to the North American plains and prairies. Native Americans used rudbeckia as a medicinal plant. Rudbeckia traveled to England in the 1600s with a British plant collector and charmed its way into English gardens, then came back to America as an ornamental in the 1800s. Today the native Rudbeckias grace our prairies, fields and roadsides, and ornamental varieties cheerfully adorn our gardens.
Members of the aster family, there are 25 species of rudbeckia. This includes perennials, biennials and annuals range in size, form and color. They generally bloom from the middle of the summer into fall.
What's not to like about these sunny flowers that vary from gold to orange to lemon to bronze? They're easy to grow. Give them a sunny spot in the garden and moist well-drained soil and they'll be happy. However, they will tolerate a variety of soil types, drier soil conditions and even light shade. While they have few pest problems, be aware that excess fertility can lead to weak growth with droopy stems.
Perennial rudbeckias will bloom the first year if started from young transplants early in the season. Annuals take 10 to 12 weeks to bloom. Once flowering starts you can keep the plants blooming for longer by "deadheading" or removing the spent flowers. Do this by regularly pinching or snipping off the flower stems at their bases.
Birds (especially finches and chickadees) like eating the seeds, so you may want to leave the flowers on the plant and let the seeds develop. Keep in mind, though, that this will reduce the amount of flowering and also may lead to some self-sowing. Baby seedling plants that result should be moved to give the plants space to grow. Rudbeckia flowers also are attractive to bees and butterflies.
Perennial rudbeckias do not die out in the center like some perennials and don't need regular division. If plants become crowded, they can be divided in early spring when new growth is beginning. If the plants are crowded or if sprinkler irrigation is excessive, mildew can become a problem. Good air circulation and sensible watering will limit this threat.
The National Garden Bureau points out that rudbeckia naturalizes easily and looks good with native grasses like switchgrass (Panicum virgatum), little bluegrass (Andropogon scoparius) or Indian grass (Sorghastrum nutans), and tall ornamental grasses like maiden grass (Miscanthus sinensis) and fountain grass (Pennisetum alopecuroides). Rudbeckia is great in combination with purple and blue perennials that bloom at the same time like Russian sage (Perovskia atriplicifolia) and fall-blooming asters (Aster novi-belgii or Aster novae-angliae).
Rudbeckias add natural grace to the native plant garden and the following cultivated varieties are great choices for the home garden:
-- "Goldsturm" (Rudbeckia fulgida var. sullivantii) -- 2 to 3 feet tall plants produce abundant pale gold flowers.
-- "Cherokee Sunset" (Rudbeckia x hirta hybrida) -- 30-inch tall plants produce 2- to 4-inch flowers in a mix of semi-double and double flowers in autumn shades of yellow, orange, bronze and mahogany.
-- "Indian Summer" (Rudbeckia hirta) -- 3-foot-tall plants with 5- to 9-inch golden-yellow flowers.
-- "Becky" (Rudbeckia hirta var. pulcherrima) -- dwarf 10 to 12-inch-tall plants produce 3-inch orange, yellow and cinnamon bicolor flowers.
One thing last thing you might want to know about rudbeckia is that it makes a super cut flower, lasting up to three weeks in a vase.
* Marianne C. Ophardt is a horticulturist for the Washington State University Extension Office in Benton County.