Cosmos Planting Methods and Key Technical Points

Cosmos (scientific name: Cosmos bipinnata  Cav.), also known as garden cosmos and autumn cosmos. It is an annual or perennial herb, 1-2 m tall. The roots are spindle-shaped, with many fibrous roots, or adventitious roots near the base of the stem. The stem is hairless or slightly pubescent. The leaves are bipinnately parted, with linear or filiform-linear lobes. The flower heads are solitary, 3-6 cm in diameter. The outer phyllaries are lanceolate or linear-lanceolate, nearly leathery, pale green, with dark purple stripes.

Planting Methods

1. Growing habits: It likes sunlight and a cool climate. It is not cold-tolerant, and it also fears intense heat. It is a short-day plant that flowers under short-day conditions in autumn, but it requires sufficient light. It is vigorous and not fussy about soil, and can tolerate poor soil. It is commonly seen growing on thin soil along roadsides, but loose soil rich in humus is preferable.

2. If base fertilizer is applied at the planting site, no further fertilizing is needed during the growing period, to prevent excessive vegetative growth and poor flowering. Cosmos originally mostly bloomed after autumn, but current hybrids can bloom from June-July to September-October. The seeds are capable of self-sowing; after maturing they can scatter and open, and germinate and grow on their own in the nursery the following year.

3. ·Propagation management: Propagate by sowing or cuttings. Sow in early to mid-March; the suitable temperature is 20°C. If the temperature is suitable, seedlings can emerge 6-7 days after direct sowing. After emergence, thin the seedlings appropriately. No special management is needed during the growing period.

4. Cosmos can also reproduce by self-sowing. Softwood cuttings can be used during the growing period, and the survival rate is also high. That is, cut healthy shoot tips of about 15 cm and insert them into sandy loam soil, shade appropriately and keep moist, and roots will form in 5-6 days. Cosmos plants are tall, so when planted in windy spots, supports should be set up to prevent lodging and breakage. They are generally grown as dwarfed plants, that is, pinch out the growing tips when the seedlings are 20-30 cm tall, and then repeatedly remove the new terminal buds several times afterward; the plants will then be dwarfed, while also increasing the number of flowers and enhancing ornamental value. The planting bed is suitable for a light application of base fertilizer.

5. Because the seeds tend to fall off after maturing, harvest the flower heads whose achenes have slightly turned black in the early morning when humidity is higher, to prevent the achenes from scattering in a radial pattern and falling at a touch during the hot, dry midday. ·Pest and disease control: Leaf spot and powdery mildew are likely to occur in hot, humid seasons, and can be sprayed with a 500-fold dilution of 50% thiophanate-methyl wettable powder. Aphids and scarab beetles can be killed by spraying with a 2500-fold dilution of 10% deltamethrin EC.