Black-Eyed Susan Planting Methods and Care Tips
Black-Eyed Susan (scientific name: Rudbeckia laciniata L.): also known as black-eyed Susan, yellow daisy, yellow chrysanthemum, false sunflower, etc. It belongs to the order Asterales, family Asteraceae, and is a perennial herb. The stems are hairless or slightly covered with short stiff hairs. The leaves are alternate, hairless or sparsely covered with short hairs. The capitulum is borne singly at the tip of the branch, with a long peduncle. The involucre is hemispherical; the receptacle is spherical; the ray florets are golden yellow; the ligules are oblanceolate; the disc florets are yellow or yellow-green. The achenes are hairless, slightly 4-angled. The flowering period is from July to October.
Black-Eyed Susan planting methods and care management
Plug tray seedling raising
Transplanting: 3 to 4 weeks after germination, transplant into 6 to 8 cm pots; after 5 to 6 weeks, transplant into 10 to 17 cm pots or 3 to 5 liter containers. Two transplantings are beneficial to plant quality. For plants used for cut flowers, a spacing of 25 to 30 cm × 30 to 35 cm is suitable.
Substrate: A well-drained, breathable growing medium is required. The clay content in the substrate is 20% to 30%. Apply 1 to 1.5 kg of completely balanced fertilizer and no more than 2 kg of slow-release fertilizer (3 to 6 months) per cubic meter of substrate. The substrate is required to contain iron chelate and trace nutrients, with a pH of 5.8 to 6.2.
Light: Long-day conditions (14 to 16 hours) are conducive to flower bud differentiation. Maintaining a high light level is beneficial for thick stems and improved plant quality. In winter and early spring, both potted and cut flower products require supplemental lighting, and lighting can be interrupted at night. A period of short-day conditions can control plant growth. After transplanting, placing plants under short-day conditions (10 hours) for 7 to 10 days during weeks 2 to 5 can promote a compact plant shape. After that, switch to long-day conditions (14 to 16 hours).
Temperature: The optimum temperature for growth is 18°C to 25°C. Black-Eyed Susan requires a warm climate for growth. Temperatures below 16°C will extend the cultivation time by more than three weeks and cause the leaves to turn red. It is not frost-tolerant.
Fertilization: The fertilizer requirement is moderate. Apply 100 ppm to 150 ppm of a balanced nitrogen and potassium fertilizer (N:K2O ratio of 1:1.5) weekly, and avoid high ammonium and high nitrogen levels. To prevent magnesium and iron deficiency, spray 1 to 2 times with magnesium sulfate at a concentration of 0.05%, and 1 to 2 times with iron chelate, respectively.
Watering: Because Black-Eyed Susan plants are slender, watering should be appropriately moderated during the growing period to suppress excessive growth and prevent lodging. It prefers a low-humidity, ventilated, and breathable growing environment. Avoid overwatering and excessive dryness; excessive dryness can cause necrosis of the leaf margins. When grown in a cool greenhouse, watering from above the plants is strictly prohibited, and humidity must not be too high in the later stage, to prevent the breeding of Botrytis cinerea.
Staking: When the plants grow to more than 1 m, stakes should be set up promptly for tying to prevent the stems from being broken by the wind. To promote the growth of side branches and prolong the flowering period, promptly cut off the spent flowers after the first bloom fades.