Rudbeckia (a.k.a. black-eyed susan)

Rudbeckias, also known as black-eyed susans and sometimes coneflowers (which is why it’s always best to use correct species names) are the star of my garden right now. I grow two species: R. subtomentosa and R. triloba. You could consider them as variations on a black-eyed-susan theme.

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R. submentosa, or sweet black-eyed susan, is a tough (you might say assertive) perennial that grows up to about 6′ high and blooms from July through first frost. Individual flowers are large–about 4″–and there are gazillions of them. This plant is completely pest- and disease free and the deer and rabbits mostly leave it alone. Like all native prairie flowers, it is a magnet for pollinators, although Rudbeckias do not seem to attract butterflies except for the occasional hairstreak.

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R. triloba, or brown-eyed susan, can only be described as adorable. The flowers are fairly small, about 2″ across, and a brilliant Crayola yellow-orange. This plant is smaller overall than R. submentosum, reaching about 3-4′. It does not spread underground like R. submentosum and is not truly perennial. Individual plants seem to last 3-4 years, but it self-seeds in my garden, so I always have seedlings. It is also pest- and disease-free, but it tends to be eaten by deer and rabbits. (I spread the plants around so the critters don’t find all of them.)

Members of this genus may be perennials, annuals, biennials, or triennials. The common black-eyed susan (R. hirta) is a biennial. In my experience, they take two years to bloom from seed or after being moved, as is true for most prairie plants. they need time to develop large root systems.

All Rudbeckias are native to North America., The genus belongs to the aster family (Asteraceae), and all species have flowers that botanists call composites. (Sometimes the family name Compositae is used instead.) That’s because all the plants in this family have flower heads made up of many tiny individual flowers. The brightly colored petals are actually rays, and the actual flowers make up the center disk. In all composite flowers, the individual flowers actually bloom in rows from the outside of the disk inward. You can often see pollinators working their way around the circle going from tiny flower to flower. Here’s a picture that clearly shows a flower head with the outer circle of flowers in bloom:

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The Asteraceae is a huge plant family that includes many native perennials (asters, echinacea, sunflowers), many familiar, though nonnative, garden plants (yarrow, marigolds, daisies), and many important food plants (artichokes, lettuce, sunflower seeds and oil). The many native perennials in this huge, happy family help bring variety, beauty, and sustainability to the garden. Plant some for yourself, and enjoy them for many years to come.

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2 thoughts on “Rudbeckia (a.k.a. black-eyed susan)

  1. Pingback: September All-Stars – Part 1 | The Garden Diaries

  2. Pingback: In a Vase on Monday: 6/30/14 | small house/BIG GARDEN

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