How to grow potted cosmos? A full analysis of care methods
Cosmos, also known as autumn English and large cosmos, is an annual or perennial herbaceous plant of the genus Cosmos in the Asteraceae family. It has a tall plant form, elegant leaves, and rich flower colors, and is suitable for flower borders. It is planted in patches along grassland edges, around tree clusters, and beside roads for beautification and greening. Double-flowered varieties can be used as cut flowers and are suitable as background material for flower borders. Now let us take a look at how to grow potted cosmos!
Growth habits of cosmos
Cosmos is native to Mexico in the Americas and is widely cultivated in China. It also often grows spontaneously beside roads, on field ridges, and along 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, dislikes waterlogging, is not suited to high summer temperatures, and is not cold-tolerant. It needs loose, fertile loam with good drainage. Cultivated varieties include white-flowered cosmos, large-flowered cosmos, and purple-red flowered cosmos. Horticultural varieties are divided into two major systems, early-flowering and late-flowering, and are also divided into single and double flowers.
Propagation methods for cosmos
1. Sowing: Sow cosmos seeds in an open-field seedbed in late March to early April. They can also germinate when the soil temperature is as low as 15°C. However, 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 50-70 days after sowing, so sowing should be divided into early-flowering and autumn-flowering sowings.
2. Cuttings: Cuttings are propagated in May. Select thick, strong terminal shoots and cut a section 8 cm to 10 cm long as a cutting. Insert 3 to 5 cuttings as a clump into a flower pot. 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 encourage more branching. If fertilizer and water are controlled properly, flowers can be seen in about 45 days.
How do you grow potted cosmos?
1. Transplanting: Transplant cosmos seedlings when they have 4-5 true leaves, and pinch off the growing tips. 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 do not set seed easily. Cosmos is a short-day plant. Spring-sown seedlings often have luxuriant branches and leaves but fewer flowers, while summer-sown seedlings are short, neat, and bloom continuously.
2. Light: Cosmos is vigorous, likes sunlight, tolerates drought, and has no strict soil requirements, but it cannot tolerate waterlogging. If it is planted in fertile soil, it easily causes excessive growth of branches and leaves and affects flower quality.
3. Fertilizing: Transplant cosmos when the seedlings are 5 cm tall, and plant them in place when they have 7-8 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 fermented urine diluted with 5 times water once every 10 days.
4. Pinching: Cosmos is a short-day plant. Spring-sown seedlings often have luxuriant leaves but few flowers, while summer-sown seedlings are short, neat, and bloom continuously. It grows rapidly, so it can be pinched multiple times to increase branching. Cosmos plants are tall, and when planted in windy places, supports should be set up to prevent lodging and breakage. Generally, dwarf plants are mostly grown, that is, remove the top when the seedlings are 20-30 cm tall, and then continue removing the new terminal buds several times in succession. The plant will 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 fermented urine diluted with 5 times water once every 10 days. Tall and medium-height varieties need supports before flowering to prevent lodging from wind damage. It grows rapidly, so it can be pinched multiple times to increase branching. Red spider mites are likely to occur in hot weather and should be controlled early. If sown from late July to early August, it can bloom after 50-60 days, and the plants will be short and neat, for use on National Day.