The Black-eyed Susans’ (Rudbeckia hirta) are biennial plants that produce nectar that attracts butterflies, bees and other insects which can be potential food for birds. It also provides shelter for several song and game birds. Black-eyed Susans usually are used in treatment of critical areas subject to erosion! This plant is incredibly winter hardy; it can tolerate temperatures as low as -30⁰F.
The black-eyed Susan grows to be about 3 feet tall (about 1 m) with bright yellow ray flowers that are 2 to 3 inches wide and have small, dark brown spherical centers. Don’t worry if your black-eyed Susan seeds do not produce flowers the first year! They typically bloom in the summer and fall of the second year. Unfortunately, the plants die after producing flowers and having their seeds mature. Fortunately, however, once established, new seedlings will be produced from the plant before it dies.
A few favorite Black Eyed Susan varieties
Formally known as Rudbeckia, Black Eyed Susans come in many varieties. Here are a few you may come across:
- Indian Summer (Rudbeckia hirta var. hirta)—These drought-tolerant annuals have a classic look and grow somewhere between three and four feet tall. Indian Summer petals are golden-yellow and can grow up to nine inches across.
- Gloriosa Daisy (Rudbeckia hirta)—These produce large flowers and can bloom in a number of colors, though yellow and orange are the most common. These perennials will usually grow somewhere between two and three feet tall.
- Clasping Coneflower (Rudbeckia amplexicaulis)—These annual, yellowish-orange flowers grow between one and two feet tall. They are notable for their delicate and somewhat cone-like shape, with oblong leaves that seem to clasp the stem. Clasping Coneflowers are also drought-tolerant and bloom in the spring and summer.
- Sweet Coneflower (Rudbeckia subtomentosa)—These perennials can grow up to five feet tall and have a long blooming period. They grow best in late summer or early fall.
When Do Black-Eyed Susans Bloom?
Black-eyed Susans bloom in different seasons depending on if the plant is annual or a perennial.
The annuals bloom throughout summer and die during winter. The cycle begins again in spring with the seeds germinating and continues to bloom in summer. The annuals include varieties like Clasping Sunflower (Rudbeckia amplexicaulis)
Other varieties are biennial meaning they germinate in spring but flower in the second year. But if you can plant the same seeds of this variety indoors about 6 weeks before the last frost date, you will be rewarded with flowers within the first year. This variety includes the familiar roadside black-eyed Susans (Rudbeckia hirta).
While it may flower in the first year, you cannot count on this plant to flower every year so enjoy it when it happens.
The perennials include Sweet Black-eyed Susans (Rudbeckia subtomentosa) available in seeds or the cultivars of Goldstrum (Rudbeckia fulgida ‘Goldstrum). These flowers will return every year to light up your fall garden.
To extend your flowering period, pinch off the spent blooms at the base of the stem. You can also cut back the stem of the black-eyed Susans after they flower.
This encourages a second surge of blooms later in the fall. Pinching, also known as deadheading which not only encourages more blooms but a sturdy compact plant.
How to Grow Black Eyed Susans
When to plant:
Although black-eyed Susans can often be purchased as bedding plants in the spring, they are very easy to grow from seed and you’ll have a much broader selection of cultivars to choose from. You can start the seeds indoors in early spring about 10 weeks before your climate’s last frost date or sow them directly in the garden in spring or summer. Perennial varieties can be sown from seed or transplanted in fall or early spring. For the best seed germination, plant when the soil temperature has warmed to about 70° F.
Where to plant:
Rudbeckia will thrive in just about any sunny location that has well-drained soil. They will tolerate drought better than they will soggy ground. If you live in a hot, humid climate, choose a spot in the garden where your plants will receive ample air circulation to avoid the development of powdery mildew.
Sowing directly in the garden:
Scatter seeds then gently press them into the soil or cover with a very light layer of soil. Water regularly to keep the seedbed moist. As seedlings grow, thin to 6 to 12 inches apart for dwarf varieties and annuals and 18 to 30 inches apart for perennials, depending on the mature size of the plant. Water thoroughly to keep the soil moist until your plants become established. Once they are well-rooted, they will be able to tolerate dry conditions.
Sowing seed indoors:
Sow seed indoors following the seed packet’s directions for planting depth, growing medium, and watering requirements. As soon as the seedlings emerge, provide plenty of light by placing them on a sunny windowsill or beneath fluorescent plant lights. Before planting your seedlings outdoors, be sure to accustom them to outdoor conditions by keeping them in a cold frame or another sheltered spot for a week.
How to Care for Black Eyed Susans
Once established, Black-eyed Susan plants bloom better if you water occasionally during dry spells. You can deadhead, or clip off old blooms, to encourage the plant to keep blooming. Or you can leave the seed heads over the winter for the birds and to provide some interest in the winter landscape.
In early spring, don’t be too quick to pull them up if it looks like nothing is happening. The growth comes from the base, so it takes time, especially after a hard winter. If you want to make more plants, cut off pieces from the edge of the plant with a garden spade in mid-spring and plant elsewhere in your garden. Or dig up the whole plant and divide into four pieces, says Horvath.