Cosmos: Airy, Effortless Color
Cosmos bipinnatus
Cosmos are the easiest cut flower you will ever grow. Scatter seeds on bare soil in spring and you get 4-foot wands of pink, white, and magenta blooms by July. Drought-tolerant, pollinator-friendly, reseeds itself.
Specifications
- Sun
- Full sun
- Water
- Low
- Hardiness zones
- Annual
- Height
- 2–6 ft
- Bloom time
- Mid-summer to frost
Care & growing tips
Direct-sow after last frost in poor to average soil — rich soil causes floppy growth. Pinch seedlings when 12 inches tall for bushier plants. Stake tall varieties in windy sites. Deadhead or cut for bouquets to prolong bloom.
Companion plants
03Place cosmos in your real yard
Upload a photo and Arden visualizes full garden designs featuring cosmos alongside companion plants.
Frequently Asked Questions
01 Why are my cosmos all leaves and no flowers?
Too-rich soil or overfeeding — cosmos evolved on lean soil and respond to fertility with leggy foliage at the expense of blooms. Stop fertilizing, water only during drought, and next year plant in poor soil. Pinch tall stems to force branching and flowering.
02 Do cosmos reseed themselves?
Generously. Let some flowers go to seed in fall, don't mulch heavily that area, and you'll have volunteer seedlings next spring. They often hybridize into unexpected colors over time.
03 How tall do cosmos get and do they need staking?
Sensation series reach 4–6 feet and need staking or support in windy spots. Sonata and dwarf series stay 2–3 feet and rarely flop. Pinching seedlings at 12 inches makes all cosmos bushier and less likely to topple.