Growing Cosmos

CosmosNative to Mexico, Cosmos (Cosmos bipinnatu) were first discovered by Spanish plant collectors and sent back to Europe in 1799. Cosmos were not introduced to the commercial seed trade until the late 1800′s and did not gain popularity until new early-blossoming varieties were developed in the early part of this century. Growing cosmos adds beauty to gardens, especially when planted in a random pattern or used as a border. Excellent in floral arrangements, too! Half-hardy annual, 4-5 feet tall.

Site Preparation:

Easy to grow, cosmos thrives in full sun and will flower more abundantly in poor soil than in rich. Requires little water and little attention. Excellent for xeriscaping (water-conserving landscape design).

Tip: Cosmos attracts beneficial insects and butterflies to the garden.

How to Plant:

Grow annuals from seed only. Sow outdoors 1/8 inch deep after last frost or indoors 4-5 weeks before last frost. Seeds will germinate in 3-10 days. Cosmos is not a heavy feeder. Too much fertilizer will cause plants to produce excessive leaf growth at the expense of flower production. Trim spent blooms on a regular basis to extend the flowering period. Remove plants, and discard in fall, after the first hard frost.

Insects and Disease:

Cosmos does not have serious problems with insects or diseases.

Seed Saving Instructions:

Cosmos is self-seeding. You can save the seed if you’re interested, but the flowers won’t always come true to type; fancy varieties often revert to the simple single-flower form.

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