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Cosmos bipinnatus (Garden Cosmos / Mexican Aster)
The ultimate carefree summer flower β airy, feathery, and impossible to fail with. Native to Mexico, cosmos produces 3- to 5-inch daisy-like flowers in pink, white, red, crimson, and maroon on tall, wiry stems that sway beautifully in the breeze. It thrives on neglect, loves poor soil, blooms non-stop until frost, and self-seeds year after year. A pollinator magnet and a cutting garden favourite.
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easy
Full Sun (6β8 hours; afternoon shade tolerated in extreme heat)
Low β water regularly until seedlings establish, then reduce to once a week; overwatering leads to fewer flowers; drought-tolerant once mature
60β90 days from seed to first bloom; flowers continuously until first frost
Direct sow seeds outdoors after last frost, scattering them ΒΌ inch deep on the soil surface in a sunny spot. Germination occurs in as little as 7β10 days once soil reaches 65Β°F. Thin seedlings to 12β18 inches apart when they reach 3 inches tall. Cosmos prefer soil that is not too rich β rich soil encourages leafy foliage at the expense of blooms, so avoid compost or fertilizer. Deadhead spent flowers regularly to keep blooms coming. If spring-sown cosmos have gone to seed by midsummer, cut the plant back to 12β18 inches to encourage a fresh flush of blooms in late summer and fall.
Germination (7β10 days)
Seeds sprout quickly in warm soil; keep surface moist until shoots emerge
Seedling (2β3 weeks)
Delicate, feathery fern-like true leaves appear; thin to proper spacing
Vegetative (3β4 weeks)
Wiry stems grow rapidly, reaching 2β4 feet; plant focuses on leafy growth before flowering
Budding (1β2 weeks)
Round buds form at stem tips; pinch early buds to encourage more branching if desired
Full Bloom (Ongoing)
Daisy-like flowers open in waves; deadhead to keep blooming non-stop until frost
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Community Interest
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