Extension Educator, Horticulture
No flowers scream summer like black-eyed Susans. They are cheerful sunny daisies with dark eyes. However they can be a confusing lot since many different plants have the same common name. And to confuse things further some are really green-eyed Susans and brown-eyed Susans. Here is definitely one time where you should know the botanic name. You may think, "ugh! another botanic name," but this is the only way you can be fairly sure you get the plant with the characteristics you want.
Black-eyed Susans are in the genera Rudbeckia. Take a look at the daisy type flower and it's easy to see they are a member of the sunflower family, Asteraceae. There are about 25 different species and they may be annual, biennial or perennial. Many reseed themselves. These sun lovers are native to different parts of North America including the moist woodlands of the southeast or the prairies of the Midwest and Great Plains.
Black-eyed Susans are known for their long bloom period and survivability. Most start blooming with yellow to yellow-orange flowers in summer and continue until fall. The flower heads remain attractive even after the petals fall and the seeds provide food for birds. With the variety of sizes they look good in naturalized areas and flower gardens.
Some notable perennial black-eyed Susans include:
'Goldsturm' (Rudbeckia fulgida var. sullivantii 'Goldsturm') – This one is easily found in garden centers, and although it is common, it is well worth growing. Its large 3-4 inch yellow orange flowers appear July through October and cover the uniform compact 2-3 foot tall plants.
'Goldquelle' alias 'Gold Fountain' (Rudbeckia laciniata 'Goldquelle') - has bright yellow flowers with double the petals. The 3 1/2 inch flowers appear mid July through September on 30 inch tall plants.
'Herbstonne' alias 'Autumn Sun' (Rudbeckia nitida 'Herbstonne') - is taller at 6 to 6 1/2 feet tall. It is quite nice as a background plant and does a good job of not flopping over. The flowers are bright yellow with green centers that appear later from August through October.
Great coneflower (Rudbeckia maxima) is not as common but a stately plant worth seeking. It has large wonderful blue green leaves almost cabbage like with bright yellow cone type flowers. This plant has conflicting information as to its winter hardiness. Although it is often listed as zone 6 the Chicago Botanic Garden has successfully grown it in their trial gardens. I believe it may be short lived due to water requirements. The Champaign County Master Gardeners have a nice clump on the east side of the Idea Garden in Urbana. It is native to the moist pine woods of Arkansas, Louisiana and Texas. It is sometimes called the swamp coneflower and supposedly likes wet feet. I had it in just such an area and it lived only a few years. A plant well worth growing but you may have to kill a few before you find the right spot where it is happy.
'Summer Sun' is a nice annual that reseeds itself to act as a perennial.