How to Grow Potted Cosmos? A Detailed Guide to the Latest Care Methods

Cosmos is also known as autumn english, large cosmos, etc. It is an annual or perennial herbaceous plant of the genus Cosmos in the Asteraceae family. The plant is tall, the leaf shape is elegant, and the flower colors are rich. It is suitable for arranging flower borders, and for mass planting on grassland edges, around tree clumps, and along roadsides for beautification and greening. Double-flowered varieties can be used as cut flower materials and are suitable as background material for flower borders. Now let us take a look together at how to grow potted cosmos!

Growth Habits of Cosmos

Cosmos originated in Mexico in the Americas and is widely cultivated in China. It also often grows spontaneously along roadsides, field ridges, and stream banks, with large areas naturalized in Yunnan and western Sichuan. It is a light-loving plant, likes light, tolerates poor soil, dislikes fertilizer, and dislikes excessively fertile soil. It dislikes heat and waterlogging, is not adapted to high summer temperatures, is not cold-tolerant, and needs loose, fertile, and well-drained loam. Cultivated varieties include white cosmos, large-flowered cosmos, purple-red cosmos, etc. Horticultural varieties are divided into two major systems, early-flowering and late-flowering, and are also divided into single and double flowers.

Propagation Methods of Cosmos

1. Sowing: For cosmos, sow seeds in an open-field seedbed in late March to early April. They can also germinate at a relatively low soil temperature of 15°C, but if sown very early, they will grow into huge plants 2 m tall and are prone to lodging due to typhoons or the weight of the plant. There are also early-flowering varieties that bloom 50 to 70 days after sowing, so sowing should be divided into early-flowering and autumn-flowering types.

2. Cuttings: Cutting propagation is carried out in May. Select thick top shoots and cut a section 8 cm to 10 cm long as a cutting. Insert 3 to 5 cuttings as a clump into a flowerpot. The pot should be buried in the soil, with 4 cm to 5 cm exposed above the ground. Water and shade it, and roots will form after half a month. After rooting, apply a thin fertilizer solution once every 15 days. When it grows to 15 cm, remove the terminal bud again to promote more branching. If fertilizer and water are controlled properly, flowers can be seen in about 45 days.

How to Grow Potted Cosmos?

1. Transplanting: Transplant cosmos seedlings when they have 4 to 5 true leaves, and pinch them. Thinning after direct sowing is also possible. If base fertilizer is applied to the planting site, no further fertilization is needed during the growing period. If the soil is too fertile, the branches and leaves tend to grow excessively and flowering decreases. Plants that bloom during the high-temperature period from July to August are not easy to set seed. Cosmos is a short-day plant. Spring-sown seedlings often have lush branches and leaves but fewer flowers, while summer-sown seedlings are short, neat, and bloom continuously.

2. Light: Cosmos is very robust, likes sunlight, tolerates drought, and has no strict requirements for soil, but it must not be waterlogged. If it is planted in fertile soil, it easily causes excessive growth of branches and leaves, affecting flower quality.

3. Fertilizing: Transplant cosmos when the seedlings are 5 cm tall, and plant them in place when they have 7 to 8 leaves. Thinning after direct sowing is also possible. If base fertilizer is applied to the planting site, no further fertilization is needed during the growing period. If the soil is too fertile, the branches and leaves tend to grow excessively and flowering decreases. Alternatively, during the growing period, apply diluted decomposed urine at 5 times the water once every 10 days.

4. Pinching: Cosmos is a short-day plant. Spring-sown seedlings often have lush leaves but fewer flowers, while summer-sown seedlings are short, neat, and bloom continuously. It grows rapidly and can be pinched multiple times to increase branching. Cosmos plants are tall, so when planted in windy places, supports should be set up to prevent lodging and breakage. Generally, dwarf plants are mostly cultivated, that is, remove the top when the seedlings are 20 to 30 cm tall, and then continuously remove the new terminal buds several times afterward. The plant can then be dwarfed, and the number of flowers will also increase.

5. Management: Cosmos has no strict requirements for fertilizer and water. During the growing period, apply diluted decomposed urine at 5 times the water once every 10 days. Tall and medium varieties need supports before flowering to prevent lodging from wind damage. It grows rapidly and can be pinched multiple times to increase branching. Red spider mites are likely to occur in hot weather, so control should be carried out early. If sown from late July to early August, it can bloom after 50 to 60 days. The plants are short and neat, and can be used for National Day.