Cosmos Cosmos bipinnatus
Cosmos (Cosmos bipinnatus) is an annual flowering plant in the Asteraceae family. It grows 80 cm–1.5 m (31 in–4.9 ft) tall and 40–60 cm (16–24 in) wide, wants full sun and low water, and is hardy to about 2 °C (36 °F). Space plants about 40 cm (16 in) apart.
Plan Cosmos in your garden →
Free. Draw your beds, then watch it grow through the year in 2D and 3D.
Cosmos at a glance
| Type | Annual flowering plant |
|---|---|
| Family | Asteraceae |
| Mature height | 80 cm–1.5 m (31 in–4.9 ft) |
| Mature spread | 40–60 cm (16–24 in) |
| Spacing | 40 cm (16 in) centre to centre |
| Sun | Full sun, at least 6 h of direct sun a day |
| Water | Low; drought tolerance moderate, waterlogging tolerance none |
| Cold hardiness | About 2 °C (36 °F) once established (roughly USDA zone 10) |
| Heat stress | Likely above about 35 °C (95 °F) |
| Flowering | about 8–11 weeks after planting, for 11–17 weeks |
| Days to maturity | About 80 days from planting |
| Wind tolerance | Low |
| Pollinator value | High |
| Edible | Not grown as food |
| Common in gardens of | 🇺🇸 United States, 🇲🇽 Mexico, 🇧🇷 Brazil, 🇯🇵 Japan, 🇦🇺 Australia, 🇹🇭 Thailand, 🇮🇳 India |
Is Cosmos toxic?
- People: not known to be toxic
- Cats: not known to be toxic
- Dogs: not known to be toxic
Cosmos is listed as non-toxic to cats and dogs.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Cosmos
Good neighbours
- good With Zucchini (courgette): Pollinator-attracting flowers can increase insect visits for insect-pollinated crops nearby. Evidence C
See Cosmos in a botanical garden
It grows in these sample gardens, which you can walk through in 3D:
- Longwood Gardens (14 plants)
- Monet’s gardens at Giverny (70 plants)
- Riverside botanical garden (20 plants)
Questions about Cosmos
- How far apart should I plant Cosmos?
- About 40 cm (16 in) apart, centre to centre. A mature plant spreads 40–60 cm (16–24 in).
- Does Cosmos need full sun?
- Full sun: at least 6 hours of direct sun a day.
- How much water does Cosmos need?
- Low water. Drought tolerance is moderate and waterlogging tolerance none.
- How cold-hardy is Cosmos?
- It tolerates about 2 °C (36 °F) once established, roughly USDA zone 10. As an annual it is usually planted out after the last frost.
- When does Cosmos flower?
- About 8–11 weeks after planting, for 11–17 weeks.
- Is Cosmos poisonous to cats and dogs?
- For cats it is not known to be toxic; for dogs not known to be toxic; for people not known to be toxic. Cosmos is listed as non-toxic to cats and dogs.
- What grows well with Cosmos?
- Pollinator-attracting flowers can increase insect visits for insect-pollinated crops nearby.
Sources and evidence
Evidence grade C (C: plausible, mixed evidence).
- ASPCA Toxic and Non-Toxic Plant List, ASPCA
- FAO Irrigation and Drainage Paper 56 — Crop Evapotranspiration, FAO
- RHS Plant Finder, Royal Horticultural Society
- University extension gardening guides (general), Various land-grant university extensions
Notes and assumptions
- Typical garden-cultivar values; varieties differ.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
Related plants
- Lettuce Lactuca sativa
- Sunflower Helianthus annuus
- French marigold Tagetes patula
- Zinnia Zinnia elegans
- Purple coneflower Echinacea purpurea
- Black-eyed Susan Rudbeckia hirta
- French tarragon Artemisia dracunculus
- German chamomile Matricaria chamomilla