Garden Cosmos
Cosmos bipinnatus
Airy, feathery foliage topped with cheerful daisy blooms in shades of white and pink that bees and butterflies adore.
A frost-tender warm-season annual in USDA zones 9-11; sow after the last low-desert frost for summer-to-fall bloom, and it reliably reseeds in mild winters.
AMWUA Notes
A fast, easy warm-season annual that delivers big pollinator-friendly color from a single spring sowing.
Care Guide
Water weekly while growing and blooming; cosmos is fairly drought tolerant but flowers best with steady moisture and dislikes soggy soil.
Deadhead spent daisies regularly to prolong bloom and keep the plant from going to seed too soon; pinch young tips once to encourage bushier plants.
Avoid rich soil and nitrogen fertilizer, which produce lush foliage and few flowers; lean soil yields the best bloom.
Occasional aphids on new growth; otherwise clean and easy.
A warm-season annual in the low desert; sow after frost for a summer-fall show, and let it reseed to return the following year.
Soil, Feeding & Propagation
Lean, well-drained soils; tolerates poor ground; rich soil yields foliage at the expense of flowers.
Needs well-drained soil.
None — thrives in lean desert soil without fertilizer.
Seed; direct-sow after frost (warm-season) as it resents transplanting, and it reseeds to return.
1–1.5 ft
Minimal; a shallow-rooted annual that resents transplanting and reseeds gently.
Placement Tips
- •Mass at the back or middle of a bed where the tall, airy stems create a soft, colorful haze.
- •Sow directly in place — cosmos resents transplanting and germinates readily from seed.
- •Let a few flowers set seed to reseed the patch for next season.
- •Full sun; a great cut flower and pollinator draw near a vegetable or butterfly garden.
Features
Best Uses
Ecological Value
Attracts
Companion Plants
Quick Stats
Design Styles
Include in Your Project
Love Garden Cosmos? Our landscape team sources from wholesale nurseries and can incorporate it into your design.
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Use this care guide to maintain your Garden Cosmos. Questions about your landscape? Reach out anytime.
Data from 2024 AMWUA “Landscape Plants for the Arizona Desert” guide.
Garden Cosmos — common questions
Answers for low-desert Phoenix conditions, drawn from this plant’s growing data.
How much water does Garden Cosmos need in Phoenix?
Garden Cosmos is a moderate-water annual once established. Water weekly while growing and blooming; cosmos is fairly drought tolerant but flowers best with steady moisture and dislikes soggy soil. A fast, easy warm-season annual that delivers big pollinator-friendly color from a single spring sowing.
How big does Garden Cosmos get?
Expect roughly 3 ft tall and 3 ft wide at maturity, with a fast growth rate. Allow about 1–1.5 ft of spacing when planting. Minimal; a shallow-rooted annual that resents transplanting and reseeds gently.
Can you plant Garden Cosmos near a pool?
Yes. Garden Cosmos is considered pool-friendly, meaning it stays clean enough around water features and hardscape. Litter is rated low.
Can Garden Cosmos handle Arizona heat and winter frost?
Garden Cosmos is hardy in USDA 9-11 and wants full sun. A frost-tender warm-season annual in USDA zones 9-11; sow after the last low-desert frost for summer-to-fall bloom, and it reliably reseeds in mild winters. A warm-season annual in the low desert; sow after frost for a summer-fall show, and let it reseed to return the following year.
Does Garden Cosmos have thorns?
No. Garden Cosmos is thornless, so it is safe alongside walkways, patios and play areas.
Is Garden Cosmos safe around pets?
Garden Cosmos is listed as pet-friendly in this guide. If your dog is a determined chewer, check any new plant with your vet before planting.
When does Garden Cosmos bloom in Arizona?
Garden Cosmos blooms in summer-fall, with white-pink flowers. The bloom draws bees, butterflies.
How much maintenance does Garden Cosmos need?
Garden Cosmos is low-maintenance. Leaf, flower and pod litter is rated low. Deadhead spent daisies regularly to prolong bloom and keep the plant from going to seed too soon; pinch young tips once to encourage bushier plants.
What kind of soil does Garden Cosmos need?
Lean, well-drained soils; tolerates poor ground; rich soil yields foliage at the expense of flowers. It needs no supplemental feeding. Avoid rich soil and nitrogen fertilizer, which produce lush foliage and few flowers; lean soil yields the best bloom.
Is Garden Cosmos native to Arizona?
No. Garden Cosmos is not an Arizona native; it originates from the Mexico, but it is grown successfully in low-desert landscapes here.