A Complete Guide to the Latest Cosmos Planting Methods
Cosmos is also known as large cosmos, autumn sage and so on. It is an annual or perennial herbaceous plant of the genus Cosmos in the aster family. It has a tall stature, elegant leaves and rich flower colors, and is suitable for flower borders. Planted in masses along grassland edges, around groves and beside roads, it gives a charming wild look to landscaping and greening, and it can also be planted beside hedges, by rockery, on cliff slopes, in tree beds or near homes. Now let us take a look together at how to plant cosmos!
Growth Habits of Cosmos
Cosmos is native to Mexico in the Americas, and is widely cultivated in China. It also often grows wild beside roads, on field ridges and along stream banks. There are large areas of naturalized plants in Yunnan and western Sichuan. It is a light-loving plant that likes sunshine and tolerates poor soil. It dislikes fertilizer, and soil that is too fertile, and it dislikes heat and waterlogging. It is not suited to high summer temperatures and is not cold-hardy. It needs loose, fertile loam with good drainage. The main varieties include white cosmos, large-flowered cosmos and purple-red cosmos. Horticultural varieties fall into two main systems, early-flowering and late-flowering, and there are also single- and double-flowered forms.
Propagation Methods of Cosmos
1. Sowing: In northern China, sowing is generally done from April to June, with flowering successively from June to August. From August to September the weather is hot with frequent overcast rain, so flowering is sparse, and after the autumn cool returns it continues to flower until frost. If sown from July to August, it will flower in October, and the plants will be short and uniform. In late March to early April, sow the seeds in an open-ground seedbed. They can germinate even at a low soil temperature of 15°C, but if sown very early they will grow into giant plants 2 m tall. There are also early-flowering varieties that bloom 50 to 70 days after sowing, so sowing must be divided into early-flowering and autumn-flowering batches.
2. Cuttings: Cutting propagation is carried out in May. Select thick, strong terminal shoots and cut segments 8 cm to 10 cm long as cuttings. Insert them in flower pots in clumps of 3 to 5 cuttings. The pots should be buried in the soil, with 4 cm to 5 cm left above the ground. Water and shade them, and they will root after half a month. After rooting, apply a dilute liquid fertilizer once every 15 days. When they reach 15 cm, pinch out the terminal buds again to encourage more branching. If water and fertilizer are controlled properly, flowers can be seen in about 45 days.
Planting Methods of Cosmos
1. Transplanting: Transplant when the seedlings have 4 to 5 true leaves, and pinch them. Thinning after direct sowing is also possible. If base fertilizer is applied at 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 flower during the high temperatures of July to August do not easily set seed.
2. Light: Cosmos is robust, likes sunlight and tolerates drought. It is not demanding about soil, but it must not become waterlogged. If planted in fertile soil, the branches and leaves tend to grow excessively, which affects the quality of flowering.
3. Fertilizing: Transplant when the seedlings are 5 cm tall, and plant out when they have 7 to 8 leaves. Thinning after direct sowing is also possible. If base fertilizer is applied at 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 decomposed urine diluted with 5 times water once every 10 days. In dry weather, water 2 to 3 times, and they will grow and flower well. Plants that flower during the high temperatures of July to August do not easily set seed. The seeds fall off easily once ripe, so collect them in the early morning.
4. Pinching: Cosmos grows rapidly and can be pinched several times to increase branching. Cosmos plants are tall, so when planted in windy spots, stakes should be set up to prevent lodging and breakage. Generally, short plants are produced by removing the growing tip when the seedlings are 20 to 30 cm tall, then repeatedly removing new terminal buds several more times. The plants will then be dwarfed, and the number of flowers will also increase. The planting bed should be given a little base fertilizer. For seed collection, pick the achenes when they turn slightly black, so that they do not scatter after ripening.
5. Seed collection: During the seedling stage, short-day treatment is needed for normal flowering, so the sowing time should be chosen appropriately. Direct sowing in the open ground is preferable, though raising seedlings is also possible. Cover the seeds with about 1 cm of soil after sowing. They emerge in about 5 to 10 days, and are transplanted when the seedlings have 4 to 5 true leaves. Plants that flower during the high temperatures of July to August do not easily set seed. The seeds fall off easily once ripe, so collect them in the early morning.
6. Management: It is not demanding about fertilizer and water. During the growing period, apply decomposed urine diluted with 5 times water once every 10 days. Tall and medium varieties need stakes before flowering to prevent lodging from wind damage. They grow rapidly and can be pinched several times to increase branching. Red spider mites easily occur in hot weather, so control them early. If sown from late July to early August, they will flower after 50 to 60 days, and the plants will be short and uniform, for use on National Day.