Growing cosmos from seeds

In this article, we'll tell you everything about growing cosmos from seeds, when to plant it according to the Lunar Calendar, how to care for the seedlings, and much more. But first, let's figure out what this plant is.

Cosmos is a herbaceous flowering annual or perennial in the Asteraceae family. It is also known as "Mexican aster" or "cosmos," which comes from the Greek word for "decoration." Currently, the flower is popular among gardeners and decorates flowerbeds, mixed borders, and hedges. Low-growing varieties look beautiful on windowsills. The most convenient way to grow cosmos is from seed. All varieties are propagated this way. This is easy for a novice gardener; you can sow the seeds directly into the ground or in seedling pots. Cosmos grown the first way will bloom in early summer, while those grown the second way will bloom later.

Growing cosmos from seeds

The flower can be propagated by seeds directly in the open ground or by growing seedlings. Planting directly into the soil occurs in the spring, after the soil has warmed up, in early May. For this method, select simple, common, early-blooming varieties, such as 'Sensation.' The second method involves sowing the seeds in late autumn, just before frost sets in, then covering them with snow.

The flower can reproduce by self-seeding. However, if different varieties are grown nearby, they may cross-pollinate, resulting in a different flower color the following season. Double hybrids may also fail to retain the characteristic traits of their species.

Growing from seed using seedlings will result in earlier flowering. Selected hybrids are used for this purpose. Sow in March or April.

Sowing dates by region

When to sow cosmos for seedlings depends on the climatic conditions in different regions.

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Selecting cosmos seeds for sowing

The seeds of your favorite variety can be purchased or collected after flowering in the garden. This is usually in early fall. To prevent them from spilling onto the ground, wrap the largest inflorescences in gauze. Wait until the seeds darken, then pick them and dry them in a well-ventilated area. Then collect them and store them in a cloth bag or box. The seeds can be sown within 3-4 years.

Technology of growing seedlings from seeds

The seedling method is used for earlier flowering or pre-determined landscape ideas:

• Loose, light soil is preferable for seedlings. This can be store-bought or homemade – fertile soil mixed with sand in a 1:1 ratio, with some humus and compost added.
• At home, the soil is disinfected in the oven for half an hour, then loosened and moistened.
• The seeds don't require stratification; they have a good germination rate. They are simply disinfected in a weak solution of potassium permanganate.
• The soil is compacted and the seeds are scattered at a distance of 9-10 cm in prepared boxes, 2-3 seeds are placed in separate cups, do not sprinkle, only spray, put glass on top or cover with film.
• Choose a sunny location - a southern or southwestern windowsill.
• The required temperature for germination is +18…+20 °C.
• Ventilate regularly and humidify as needed.
• After germination, after 1-2 weeks, remove the film and lower the temperature to 16-18°C to prevent the seedlings from stretching. The room should be sunny; if there is insufficient light, use photo lamps. If the seedlings emerge too densely, thin them out to 10-15 cm apart or transplant them.

Caring for seedlings

Water the seedlings moderately with soft, settled water. After 2-2.5 weeks, feed them with a complete potting mix for flowering plants. After the first pair of leaves appears, transplant the seedlings into individual containers. When 7-8 leaves have formed, remove the upper portion of the stem. This procedure is necessary to promote the growth of lateral shoots and increase the number of buds.

Two weeks before planting in the flowerbed, the future flowers are hardened off. They are kept outdoors or on a balcony, initially for 10-15 minutes, gradually increasing the time. With this method, cosmos blooms in June.

Seedlings are transplanted into open ground in mid-May, once the danger of night frosts has passed. Small planting holes are prepared 2-3 days in advance in a sunny location. Space the plants 30 cm apart for dwarf hybrids and 40-50 cm apart for taller hybrids. Water the day before and transfer the plants in the evening. Place each one, cover with soil, press lightly, and water. To encourage vigorous flowering, pinch off the tops of the cosmos when the plants reach 50 cm.

This growing method has advantages for landscape design: each flower is placed in its own spot. Tall varieties require support.

The soil should be slightly acidic, well-drained, and moderately fertile; otherwise, the cosmos will grow tall and not bloom profusely. With this method, the plant blooms in early summer.

Preparing and sowing seeds in open ground

Cosmos seeds are small and elongated. There are 200 seeds per gram. Choose a sunny location with fertile, well-drained soil, protected from cold winds. A fence is ideal, and the plant can be used as a hedge. Prepare the soil before planting: loosen compacted soil with sand and wood chips, then loosen and fertilize with organic fertilizer, then moisten.

Plant 3-4 seedlings at a distance of 3-4 cm. Plant them 10 mm deep in the soil. Seedlings should appear in 2-3 weeks. Outdoor temperatures should be between 12 and 15 °C. Thin them out when the seedlings reach 5 cm. Cosmos grown this way will bloom in July-August.

There are two methods for sowing: nest sowing or continuous sowing. Make shallow holes (no more than 1 cm) in a leveled bed and plant 3-4 seeds at intervals of 30 cm. Cover the seedlings with a thin layer of soil. Alternatively, scatter the seeds without making holes. Then moisten with a spray bottle. After germination, thin the seedlings. Leave strong, sturdy shoots and remove weak ones.