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Growing Cosmos

Growing Cosmos

Sonata Mix



Cosmos is a long-blooming annual plant ideal for garden beds, containers, and mixed plantings. Varieties are available in single and double-flowered forms in a range of heights. It is a great plant for dry, low-fertility soils, and it thrives in heat and drought. Its flowers are very attractive to butterflies, and can be used as a fresh cut flower. It may reseed in gardens if not deadheaded, but not aggressively.

How To Grow

Direct sow outside after the danger of frost has passed. Seed can also be started inside 4 to 6 weeks before outdoor planting time. Sow seed ¼ inch deep and maintain at 68 to 70 degrees. Expect germination in 5 to 14 days.


Plant in full sun or very lightly-shaded sites. Plants are both drought and heat-tolerant once established, and grow best in well-drained soils. Low to moderate feeders, and over-fertilization can lead to stretching and floppy stems. Can cut back plants by up to half their height if they become too tall. 

Fertilizer Recommendations

Cosmos is a moderate feeder and benefits from occasional fertilization. Use low rates of ALGOplus Flowering Plant 4-6-7 liquid fertilizer, Neptune Fish & Seaweed Fertilizer 2-3-1, or Osmocote slow-release 14-14-14.

Common Problems

Cosmos is generally free of serious pest and disease problems. Aphids, plant bugs, and thrips may feed on plants. Powdery mildew is an occasional problem.

Alternative Products

Other good annuals for sunny, dry locations include Denver Daisy Rudbeckia (07663), Queen Mixed Cleome (05462), and Zinnia.

Product Recommendations

Insect pests can be controlled with Captain Jack's Deadbug Brew. Powdery mildew can be treated with 70% neem oil.

Cosmos Facts

Cosmos is native to central Mexico.



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