Cosmos

Cosmos bipinnatus

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verifiedReviewed by the GreenScout Team

Cosmos are airy, daisy-like flowers with delicate feathery foliage that grow quickly and bloom prolifically throughout summer and fall. They attract butterflies and pollinators, making them excellent for cottage gardens and meadow plantings. These heat and drought-tolerant annuals thrive in poor soil and require minimal maintenance once established.

Common Problems

Select the problem your Cosmos is experiencing to get a treatment guide.

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Leggy Growthchevron_right

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Wiltingchevron_right

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Yellow Leaveschevron_right

Care Guide

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Light

Full sun; requires 6+ hours of direct sunlight for optimal blooming

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Water

Drought-tolerant once established; water moderately and allow soil to dry between waterings

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Soil

Poor to moderately fertile, well-draining soil; overly rich soil encourages foliage over flowers

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Fertiliser

Minimal fertilization needed; apply low-nitrogen fertilizer once or twice during growing season

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Temperature

Warm-season plant; thrives in 70–85°F; tolerates heat well

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Humidity

Low to moderate humidity; prefers dry conditions and benefits from good air circulation

Toxicity

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Non-toxic to cats, dogs, and children

Common Diseases

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Common Pests

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Seasonal Care

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Resume regular watering and feeding as growth picks up.

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Peak growing season. Water and feed regularly.

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Reduce watering as growth slows. Stop heavy feeding.

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Minimal watering and feeding. Protect from frost if needed.

Frequently Asked Questions

Why does my Cosmos flop over or get leggy?

Rich soil encourages excessive height and weak stems — Cosmos actually prefers poor to moderately fertile soil, since overly fertile conditions promote leggy growth over sturdy blooms.

How much care does established Cosmos need?

Very little — these heat and drought-tolerant annuals thrive in poor soil and require minimal maintenance once established, blooming prolifically through summer and fall.