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Cosmos

Cosmos bipinnatus

Flower

Cosmos are airy, fast-growing annuals with ferny foliage and jewel-toned flowers that bloom prolifically through summer and autumn. They are outstanding lacewing and parasitic wasp attractors and produce far more beneficial insect activity per square foot than most garden flowers.

Growing Conditions

Sunlight

Full Sun

Water Needs

Low

Soil

Well-draining loam; pH 6.0–8.0; thrives in poor to average soil

Spacing

12–24 inches

Days to Maturity

50–60 days from direct sow to flower

Growing Zones

1
2
3
4
5
6
7
8
9
10
11
12
13

Thrives in USDA Zones 3–11

Companion Planting

Good Companions

Keep Away From

No known antagonists

When to Plant

  • Direct Sow

    After last frost; can direct sow in autumn in mild climates

  • Harvest

    Cut stems frequently to extend flowering; self-seeds freely

Organic Growing Tips

  • Sow in poor soil — rich soil produces enormous plants with few flowers.

  • Allow to self-seed freely around the garden; cosmos creates a self-sustaining beneficial insect habitat.

  • Tall varieties can provide light, dappled shade for lettuce and spinach during hot spells.

  • Cut regularly for bouquets — constant cutting stimulates more flower production through autumn.

Common Pests

  • Aphids
  • Powdery Mildew

All pest management in Garden uses safe, organic, non-toxic methods only. No synthetic pesticides, ever.