Today our crews reviewed one of the most popular perennials, black-eyed susans, or Rudbeckia sp. The main species are:
- Rudbeckia fulgida, black-eyed susan (‘Goldsturm’ is the most common cultivar)
- Rudbeckia triloba, black-eyed susan
- Rudbeckia laciniata, cutleaf coneflower
- Rudbeckia maxima, giant coneflower
- Rudbeckia hirta, black-eyed susan (This species is short-lived and often used as an annual because it does not come back reliably after winter.)
Tips for Growing Rudbeckia
All rudbeckias are native to North America, and some are native to the southeast, such as the giant coneflower. They are excellent for use in perennial borders, pollinator gardens, natural areas, and mass plantings. They do spread, so they tend to do best planted in large swaths and allowed to colonize. They bloom longer if deadheaded, but leaving the seedheads intact will attract the birds that feed on them. The spent seedheads can actually look quite attractive in the winter landscape if left in natural areas, though sometimes they are beaten down by the rain and can appear messy. The flowers can also be used as cut flowers in arrangements.
Rudbeckias grow best in full sun, with well-drained soil, thought once established they can be quite tolerant of drought or poor soils. In wet soils, they are prone to root rot. They do not require much care to look great, and are an excellent choice for beginner gardeners experimenting with perennials. As with most perennials, fall is the best time for planting, but mid-spring is the next best time. Planting in fall allows time for the root system to grow and establish before the heat and drought stress of summer. Most pest and disease problems can be avoided with proper plant spacing and adequate soil drainage.
- Typically with most Rudbeckia species, the leaves and stems grow from a basal rosette (single clump in the center of the plant), and the leaves are dark green and lance-shaped, usually with lobed edges. They may feel rough like sandpaper to the touch. The leaf shape can vary quite a bit in appearance from species to species.
- The flowers are quite similar in shape to Echinacea. They have a central disk which may be rounded or cone-shaped, usually dark brown in color, but may also be yellow or greenish in some species. The petals (ray florets, if you want to be technical) radiate out from the central cone and are usually reflexed, drooping downward away from the cone. The petals are yellow, ranging from bright clear yellow to deep golden. On R. hirta, the flowers may be reddish brown around the cone, fading to yellow near the petals tips. Some varieties have been bred that are completely red (ruddy, brownish red).
- In winter climates with freezing temperatures, the plants may die back completely to the ground, or there may be a small basal rosette of leaves remaining.