A Detailed Guide to the Ornamental Value and Cultivation Methods of Black-Eyed Susan

[Latin name]: Rudbeckia laciniata

[Family and genus]: Asteraceae, Rudbeckia

[Alias]: Cutleaf Coneflower

[Place of origin]: Canada and the United States

Morphological characteristics

It is a perennial herbaceous flowering plant. It is generally grown as a 1-2 year plant, with rough branches and leaves, and the ground plant can reach 1-2 m in height; in pot culture it is dwarfed to 20-30 cm, and it is much branched, with relatively wide and thick leaves; the basal leaves are pinnately divided into 5-7 lobes, and the stem leaves are 3-5 lobed, with relatively dense serrated edges. The capitulum grows on the main stem, and the ray florets are in a single whorl, some oblanceolate and drooping, and some with upturned petals. The petals are about 3 cm long, and the flower spread is 3-7 cm. The flower colors include: orange-red, deep red, pink, water red and other colors. The flowering period runs from May to October, and lasts longer in the south. In addition, there is also the double-flowered Rudbeckia.

Growth habits

Rudbeckia likes a well-ventilated, sunny environment. It has strong adaptability, is cold-resistant and drought-tolerant. It is not demanding about soil, but dislikes waterlogging. It grows well in well-drained, loose sandy soil. Although it is a herbaceous plant, it also has the characteristics of a woody plant; the stems are hard and not easy to lodge, and it also has disease-resistant and insect-resistant characteristics. Therefore, it is very easy to cultivate, and at the same time it is not strongly sensitive to sunlight; whether cultivated in a sunny area or in an environment with weaker sunlight, the bright effect of the flowers is not affected. It can be propagated by division in spring and autumn, or by seed.

Main varieties

Rudbeckia laciniata is a perennial herb, 60~250 cm tall, branched, hairless or slightly covered with short coarse hairs. The leaves are relatively wide; the basal leaves are pinnately 5-7 lobed, and the stem leaves are 3-5 lobed. One to several capitula are borne on long peduncles; the involucral bracts are sparse, leaf-like, about 10 cm in diameter; the ray florets number 6-10, oblanceolate and drooping, 25-38 cm long, golden yellow; the disc florets are yellow-green; the flowering period is July-September. Native to Canada and the United States.

Rudbeckia hirta 'Rose' is a cold-resistant perennial herb, 30-90 cm tall, slightly branched in the lower part, and the whole plant is covered with coarse hairs. The leaves are alternate; the lower leaves are nearly spatulate, with winged petioles; the upper leaves are oblong to lanceolate, entire, and sessile. The capitulum is solitary at the top of the stem, about 8-10 cm in diameter; the ray florets number 14, golden yellow, 25-5 cm long, darker at the base; the disc florets change from purple-black to dark brown; the flowering period is July-October.

Ornamental uses

Rudbeckia has a relatively large plant type. During the full flowering period, the flowers are abundant and colorful, like a brocade of blooms, dazzling to the eye. It also has a long ornamental flowering period and a short leaf-drop period, and can form a brilliant sea-of-flowers landscape lasting as long as half a year. Therefore, it is suitable for landscaping in places such as parks, institutions, schools, and courtyards. It can also be used as flowerbed and flower border material, and is also a fine choice for cut flowers and vase arrangements. In addition, it can also be planted along lawn edges in a naturalistic style.

Cultivation and propagation

It can be propagated by sowing or division, but division is usually used more often, especially for double-flowered varieties. Sowing can be done in spring or autumn, but autumn sowing is better. After sowing, seedlings emerge in about 2 weeks, can be transplanted in about 3 weeks, and bloom the following year. Division propagation is best done in early spring. After digging out the underground perennial roots, divide them, ensuring that each division has more than 3 buds. Both sown seedlings and divided plants should be planted in soil with base fertilizer applied and good drainage and loose texture. After planting, water thoroughly, provide appropriate shade depending on light intensity, and remove the shade after the plants are established. Because Rudbeckia plants are slender, watering should be appropriately controlled during the growing period to inhibit tall growth and avoid lodging, and 1-2 applications of liquid fertilizer should be given at the same time. When the plants grow to more than 1 m, supports should be set up promptly for tying to prevent the stems from being broken by the wind. In order to promote side branch growth and extend the flowering period, the spent flowers should be cut off promptly after the first flowering ends.