Also known as Rudbeckia Triloba, thin-leaved coneflower, or three-leaved coneflower, this is is a biennial or short-lived perennial plant up to 5′ tall. It branches frequently at the leaf axils and its appearance is rather bushy at maturity. Individual upper stems terminate in 1-2 flowerheads. Each flowerhead is about 1½-2″ across, consisting of 6-12 ray florets that surround a brown to black flattened cone of numerous disk florets. The petaloid rays of the flowerheads are bright yellow and oblong in shape.
The blooming period occurs from mid-summer to late summer for about 1-2 months. On robust plants, 6 or more flowerheads are often in bloom at the same time, creating a showy effect.
The preference is full to partial sun, moist to medium conditions, and fertile loamy soil, although soil with some gravel or clay is tolerated. This plant has moderate drought-tolerance; it may drop some of its lower leaves or wilt should this occur. The main reason brown-eyed Susan is considered a short-lived perennial is its tendency to exhaust itself with profuse flowering, leaving it unable to set buds for next season. In her book “The Well-Tended Perennial Garden,” pruning expert Tracy DiSabato-Aust advises drastically cutting back plants that tend to wear themselves out with flowering to prevent this issue and extend their lifespan.