Sulphur Cosmos Cosmos sulphureus

Klondike cosmos is a fast growing annual with golden-yellow or orange flowers in the Asteraceae (daisy) family.  It can grow up to 6 feet tall providing sticking color from summer until the first frost. The ‘Cosmic’ series will give you lots of 2-inch double and semi-double bright, non-fading blooms in shades of orange, red, and yellow, and will get 12 to 18 inches tall on well-branched plants.

Plant cosmos in a location that receives at least a half-day of direct sunlight in moist to dry, porous soils. Sow the seeds outdoors after the danger of frost is past and when the soil has warmed to at least 65 degrees. Rake seeds into a loose soil; planting seeds too deeply will hinder germination. Keep the soil moist for 5 to 10 days after seeding. Seeds will germinate in 7 to 21 days. Cosmos needs only basic care to provide an abundance of colorful blooms all summer. Taller varieties may need staking if subjected to high winds and frequent storms.

When the spring-planted cosmos appears to have an abundance of dried seed, do not remove the plants. Encourage re-bloom by cutting the plants back to 12 to 18 inches high. They will be back in bloom in a month and the seed that is cut off will fall to the ground, germinate in the hot soil, and increase the density of your plant population and the eventual bloom display.

Use in the background as a bedding plant or in a cut flower garden.

Quick ID Hints:

• dimorphic involucral bracts in two rows
• opposite, pinnatifid leaves
• small heads 1-2" with orange ray flowers

Insects, Diseases, and Other Plant Problems:  Aphids and Japanese beetles are occasional bests.  Bacterial wilt and canker are occasional diseases.  It reseeds easily and can become weedy.

More information on Cosmos.