Cosmos (Cosmos bipinnatus)
A native of Mexico, also called Mexican Aster, Cosmos is a heat loving annual that provide abundant blooms all summer until frost. This airy plant produces tall, lanky stems with feathery leaves and colorful daisy-like flowers. The plants can grow up to 4-6 ft with dwarf varieties up to 1- 3 ft tall. The blooms come in assorted colors of white, pink, red, lavender and yellow, in single, semi-double and double forms making them an excellent cut flower.
Grow them in full sun in a well drained, dry, poor soil. They thrive on neglect; rich wet soil will produce floppy plants with many leaves and little flowers.
Start them from seeds indoors 6-8 weeks before the last frost date or sow directly outdoors after the last expected frost.
To start the seeds indoors: Sow seeds and cover lightly with soil. Germination should take 5-10 days at 70-85 degrees.
Plant seedlings outdoors 9-24″ apart. The taller varieties of Cosmos should be planted in the back of the flowerbed and may need staking. To keep tall varieties from falling over, plant them 9-12″ apart, so that they can interweave and support each other. For compact, bushier plants with more flowers pinch them back once or twice before flowers buds begin to show.
Deadhead spent flowers for continuous bloom and to prevent them from self-seeding. If you want Cosmos to self-seed next year; allow some of the seed heads to remain on the plant at the end of the season. You can also collect dry seed heads for next years planting.