Cosmea 'Cosimo Red-White' Cosmos bipinnatus 'Cosimo Red-white' (Cosimo Series)

Water

Garden cosmos should be watered regularly, aiming for at least an inch of water per week, either from rainfall or manual watering. Water deeply once a week to encourage strong root growth, rather than light waterings daily. During particularly hot or dry periods, you may need to water them more frequently. If you're using a container, check the soil moisture more often, as pots can dry out faster than garden soil. It's best to water early in the morning to reduce evaporation and allow foliage to dry out over the day, minimising the risk of fungal diseases.

Light

Garden cosmos thrives in full sun, where it can receive at least 6 to 8 hours of direct sunlight daily. The ideal spot would be an open area without shade from trees or buildings to ensure ample light and promote the most vigorous growth and flowering.

Temperature

Garden cosmos are quite tolerant of a range of temperatures, but they grow best when daytime temperatures are between 75°F and 90°F. They can survive minimum temperatures down to about 25°F but will start to suffer damage if it gets colder. For optimal growth, keep them in conditions that avoid the extremes of very hot or freezing temperatures.

Pruning

Pruning garden cosmos by deadheading, or removing spent flowers, encourages more blooms and extends the flowering season. You can also cut them back by one-third in midsummer if the plants are getting leggy. Pruning should be done regularly throughout the flowering season, usually every few weeks, to keep the plants looking tidy and encourage more blooms. The best time for pruning is when the flowers start to wilt and before they set seed.

Cleaning

As needed

Soil

The best soil mix for Cosmos (Cosmo Series) is well-draining, fertile, loamy soil with a pH of 6.0 to 8.5. You can prepare a mix using equal parts of garden soil, compost, and perlite or sand to ensure proper drainage and fertility.

Repotting

Cosmos (Cosmo Series) are typically grown as annuals and therefore do not require repotting. If started in containers, transplant them to the garden or larger pots when seedlings are large enough to handle.

Humidity & Misting

Cosmos (Cosmo Series) are not particularly humidity-sensitive and do well in average garden conditions. They do not require high humidity levels, making them ideal for a variety of outdoor environments.

Suitable locations

• Indoor

  Provide bright light and well-draining soil for Cosmos indoors.

• Outdoor

  Plant Cosmos in full sun, well-draining soil, after last frost.

• Hardiness zone

  Cosmos (Cosmo Series) are suited for USDA zones 2-11.

Life cycle

The life of Cosmos bipinnatus, commonly known as Cosmos, begins with seed germination, which occurs in warm soil after the last frost when temperatures are around 75°F (24°C). Seedlings emerge and grow into young plants with feathery foliage, which typically occurs within 7-21 days post sowing. As the plants mature, they develop long slender stems and finely cut leaves, reaching a flowering stage in about 7 weeks, where they display their characteristic red-and-white bicolored blooms. Cosmos flowers attract a variety of pollinators, and if left to their own devices, the flowers eventually fade to form seed heads, which contain seeds for the next generation. The plants continue to produce flowers throughout the growing season until the first frost. At the end of the growing season, cosmos plants die back, completing their life cycle as annuals.

Propogation

• Propogation time

  Spring-Summer

• Cosmos, particularly the Cosmos bipinnatus 'Cosimo Red-white', is most commonly propagated by seed. The best time to sow Cosmos seeds is after the last frost when the soil has warmed, usually between late March and May in the Northern hemisphere. To propagate, evenly distribute the seeds on top of well-drained soil and lightly cover them with about 1/8 inch (approximately 3 millimeters) of additional soil. Keep the soil moist but not waterlogged until germination, which typically occurs within 7 to 10 days. Once the seedlings have developed a few sets of true leaves and are sturdy enough to handle, they can be thinned or transplanted to give them adequate space to grow. Cosmos thrives in full to partial sunlight and prefers well-draining soil.