Robin Trott, UMN Extension Educator
In a few weeks our ditches and roadsides will be full of those yellow daisies known as Black-eyed Susans or rudbeckia. A native wildflower and perennial favorite, rudbeckias are reliable plants that fill our gardens with brightly colored flowers from July through the first frost. They are easy to grow, adapt to a wide variety of soil conditions, have very few insect or disease problems, and bloom the first year when started from seed. However, they weren't always a staple of American gardens.
In the early 17th century, British plant collector, John Tradescant, collected roots from French settlers in the "New World". The plant was shared with other botanists and herbalists, and was soon popular in English Gardens. By the mid-1800's, it found its way into American gardens and was noted by an early garden writer as "the darling of the ladies who are partial to yellow." It was used medicinally by Native Americans to treat both people and horses. The roots and flowers were made into teas and compresses to treat a variety of ailments, including: snake bites, worms, earaches, indigestion, burns and sores.
There are 25 species of Rudbeckia including perennials, biennials and annuals. A member of the Aster family, Rudbeckia's flowers come in single- semi-double and full double forms, and range from lemon-yellow to gold, chestnut, mahogany and bronze as well as multi-colored blooms. If you have never planted Rudbeckia, I encourage you to try some this year. They were stellar performers in our garden last year, and many marginally hardy varieties made it through our snowy winter, and are beginning to bud out. Some varieties I have successfully grown are:
Rudbeckia fulgida is perennial to zone 3. 'Goldsturm' is a 2'-3' tall plant that is long-lived and reliably produces abundant blooms from midsummer to frost. It was voted the Perennial Plant of the year in 1999.
Rudbeckia triloba, the brown-eyed Susan, is hardy to zone 4. Plants are 2'-5' tall, and the flowers are yellow with black centers that fade to brown.
The largest group of rudbeckias is Rudbeckia hirta, or gloriosa daisies. These are short-lived perennials, and are grown as annuals in our northern climate. They readily self seed, and are some of the most colorful Rudbeckia available.
- 'Indian Summer' was an All-American Selections winner in 1995. It produces giant 5"-9" flowers on 3' tall plants. The golden petals are wider than the wild variety, and the flowers make long lasting cuts.
- 'Cherokee Sunset' is a semi-double and double flower, with 2-4" blossoms in shades of yellow, orange, bronze and mahogany. These 2' tall plants are spectacular in the garden and in mixed fall bouquets.
- 'Cherry Brandy' is a 24" single flowering variety. Its long-lasting 4" blooms are cherry red at the tips darkening to deep maroon at the center. This "Susan" has the typical "black eye".
- 'Autumn Colors' is an upright compact plant just 20 to 24 inches tall and 15 inches wide. The Single and Semi-double, 5-7" flowers are a vibrant mix of oranges with deep brown and orange markings.
Rudbeckia make excellent cut flowers, with a vase life up to 21 days. Harvest rudbeckia when the flowers are fully open, during the coolest part of the day, and place in clean, warm water. Re-cut stems under water, removing about one inch, to eliminate air bubbles and bacteria. Create your floral design and place bouquet in water containing floral preservative.
Rudbeckia are ethylene sensitive. Ethylene is an odorless, colorless gaseous plant hormone that exists in nature and is also created by man-made sources. It can be produced by ripening produce, propane heaters, auto exhaust, cigarette smoke, other flowers and fungi. For longest vase life, keep your floral bouquets away from ethylene producers.
Visit your local garden center, or consider purchasing seed next year for beautiful Rudbeckias in your home garden. Whichever you choose, you won't be disappointed.