Cornflower Centaurea cyanus
Cornflower (Centaurea cyanus) is an annual flowering plant in the Asteraceae family, native to Europe and the Mediterranean (now rare as an arable weed). It grows 30–90 cm (12–35 in) tall and 15–30 cm (6–12 in) wide, wants full sun and low water, and is hardy to about -15 °C (5 °F). Space plants about 20 cm (8 in) apart.
Plan Cornflower in your garden →
Free. Draw your beds, then watch it grow through the year in 2D and 3D.
Cornflower at a glance
| Type | Annual flowering plant |
|---|---|
| Family | Asteraceae |
| Mature height | 30–90 cm (12–35 in) |
| Mature spread | 15–30 cm (6–12 in) |
| Spacing | 20 cm (8 in) centre to centre |
| Sun | Full sun, at least 6 h of direct sun a day |
| Water | Low; drought tolerance moderate, waterlogging tolerance none |
| Soil pH | 6–7.5 |
| Cold hardiness | About -15 °C (5 °F) once established (roughly USDA zone 7) |
| Heat stress | Likely above about 30 °C (86 °F) |
| Flowering | about 10–14 weeks after planting, for 6–11 weeks |
| Days to maturity | About 100 days from planting |
| Wind tolerance | Low |
| Pollinator value | High |
| Edible | Yes: petals |
| Native to | Europe and the Mediterranean (now rare as an arable weed) |
| Common in gardens of | 🇩🇪 Germany, 🇬🇧 United Kingdom, 🇫🇷 France, 🇷🇺 Russia |
Is Cornflower toxic?
- People: not known to be toxic
- Cats: not known to be toxic
- Dogs: not known to be toxic
Not listed as toxic by ASPCA; the petals are used as an edible garnish.
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 Cornflower
No well-documented helpful pairing. Group it with plants that like full sun and low water.
See Cornflower in a botanical garden
It grows in this sample garden, which you can walk through in 3D:
- Kew: glasshouses and rock garden (18 plants)
Questions about Cornflower
- How far apart should I plant Cornflower?
- About 20 cm (8 in) apart, centre to centre. A mature plant spreads 15–30 cm (6–12 in).
- Does Cornflower need full sun?
- Full sun: at least 6 hours of direct sun a day.
- How much water does Cornflower need?
- Low water. Drought tolerance is moderate and waterlogging tolerance none.
- How cold-hardy is Cornflower?
- It tolerates about -15 °C (5 °F) once established, roughly USDA zone 7. As an annual it is usually planted out after the last frost.
- When does Cornflower flower?
- About 10–14 weeks after planting, for 6–11 weeks.
- Is Cornflower 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. Not listed as toxic by ASPCA; the petals are used as an edible garnish.
- What grows well with Cornflower?
- There is no well-documented companion pairing for Cornflower. Group it with plants that like the same sun (full sun) and water (low).
Sources and evidence
Evidence grade B (B: extension service or peer-reviewed).
- RHS Plant Finder, Royal Horticultural Society
- Missouri Botanical Garden Plant Finder, Missouri Botanical Garden
- Plants For A Future database, PFAF
- Plants of the World Online (taxonomy, native range), Royal Botanic Gardens, Kew
Notes and assumptions
- Typical garden-form values; cultivars and local conditions differ.
- Hardy annual sown in autumn or spring; the autumn sowing flowers earlier. Self-seeds freely.
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
- Cosmos Cosmos bipinnatus
- Purple coneflower Echinacea purpurea
- Black-eyed Susan Rudbeckia hirta
- French tarragon Artemisia dracunculus