How to Grow Cornflower in Your Garden

What is the Centaurea Cyanus?

The Centaurea cyanus flower is also known to go by the names of Cornflower or Bachelor’s button.

It is a member of the Asteraceae / Compositae (Aster, Sunflower, and Daisy) family. As a Centaurea plant genus member it is closely related to plants such as knapweeds and Centaury.

Centaurea cyanus, the cornflower, has naturally blue flowers and is natively found on farmlands and alogside roads.
Native Coneflowers have an intense blue color. Photograph by Swallowtail Garden Seeds; CC.

It is a flower that has a bulb similar to a daisy. It grows well and in abundance during the late spring and summer seasons.

The flowers have bold and attractive colors of blue, with cultivars of pink, lavender, white, and maroon being available.

Centaurea cyanus a magnet for fluttering butterflies and bees when in bloom.

Cornflowers are a great plant to grow to attract birds and bees to your garden.
Cornflowers being pollinated by a bee. Image by David Wright under CC licence.

Centaurea Cyanus is a desirable flower to grow as they make great borders for garden beds, are very easy to grow, and are generally pest and disease-free.

Gardener’s HQ Guide to Growing Centaurea Cyanus

It is best to sow out Centaurea cyanus seeds in early autumn (fall) in warmer climates so that they can thrive the following year in late spring and summer.

Alternatively, they can be started indoors the same season, or sown directly after the last frost of spring for a later bloom.

Before you sow your seeds, one of the first things to remember is to leave plenty of space between each seed.

It is suggested to leave 8 to 12 inches between each plant as they will grow and take up the space that is left in-between them.

Be sure to sow seeds in triplicate, and then thin out straggly seedlings.

When planning to grow the Centaurea cyanus, make sure the soil that is being used is moist enough for your flowers but has good drainage. This will allow the coneflowers to sprout and not decay due to being saturated with too much wetness.

It is important that you plant your Centaurea cyanus in an area where they will get plenty of sunlight.

As they are wiry plants, they may need to have some sort of support in areas or situations where they are openly exposed.

When early spring arises, it may help to work fertilizer into the soil to allow Centaurea cyanus to grow both efficiently and abundantly.

Despite Centaurea cyanus being a flower known to tolerate conditions of dryness, they should be watered frequently to thrive.

Growing in bunches from 12 inches to 36 inches (30 to 90 cm) tall with a spread 6 to 12 inches (15 to 30 cm) wide, the Centaurea cyanus plant is easy to grow and makes an excellent choice for gardeners new and old looking for a colorful plant to naturalize garden beds.

Quick Growing and Care Guide and Facts

Scientific Name: Centaurea cyanus

Common Name (s): Cornflower, Bachelor’s buttons, Garden cornflower, Blue Bottle.

Growing Zone (USA / UK Hardiness): USDA Zones 2 to 11 / Europe/ H6 – hardy to about -20°C (-4°F).

Location in the Garden – Best used for: Beds, Borders, Wildlife garden, container gardening. Makes a great cut flower.

Plant Details

Life Cycle / Plant Type: Annual. Deciduous. Can grow as a perennial in warmer areas.

Native: Europe. Alongside roads and in fields.

Plant Height: 24 to 30 inches (60 to 75 cm). Upright habit. Long grey green stems. Fast growing.

Plant Spread: 16 to 24 inches feet (40 to 60 cm). Spacing at about 6 to 12 inches (15 to 30 cm) gives good results.

Blooms: Late spring and early summer. Autumn sowing in warmer areas for an early spring bloom. Showy.

Flower Details: Solitary flower atop long stem. Purplish blue, with white and pink cultivars common too. 1 to 1.25 inches (3 to 4 cm) diameter.

Leaf Foliage: Simple, slightly lobed, lanceshaped to about 1 to 1.5 inches (2.5 to 4 cm).

Fruit: No.

Growing Conditions and Location

Best Light Conditions: Full sunlight.

Suitable Soil Types: Average.

Soil pH: neutral to slightly alkaline (pH 6.6 to 7.8).

Soil Moisture: Medium, Good drainage. Tolerant to drought.

Sowing, planting, and Propagation: Sow seeds at the same time as the last expected frost. Or get a head start by sowing indoors about 7 or 8 weeks before the last expected of spring.

Seeds can be sown in the autumn in milder areas.

Use a moist soil and lightly cover seeds to about 0.4 inches (1 cm) when sowing. Germination typically takes a couple of weeks.

Care: Low maintenance flower. Deadhead to prevent seed set and self-seeding, and to prolong flowering. Provide support for taller varieties. Use a high phosphorus fertilizer if extra flowers are required for cutting.

Growing in pots and containers: Yes, as they are a little scraggly it is best to grow them alongside other plants. Start indoors before last frost, slowly harden outdoors. Ensure pot has good drainage. Keep soil fairly dry, watering slightly more when weather is hot. Mulching can also help to protect plants from the sun.

Cultivars and Varieties: Numerous cultivars are available. These tend to have pale pastel colors as opposed to the native purplish-blue.

These are some of the more well-known Cornflower varieties (flower colors in brackets): Blue Boy (double blue flowers); Classic Romantic – single and double flowers (Pale pink / red); Black Bell (dark crimson); Purple haze (pale semi-double flowers, white or lilac with a purple center).

Cornflowers are available in many varieties, with multiple colors including pale pink.
Pink Cornflower Variety. Photograph by chipmunk_1; CC.

Miscellaneous: Attracts birds and butterflies to the garden. Birds love the seed so do not deadhead if you wish to attract our avian friends to your garden. Bees and wasps are attracted to the flowers when in bloom. Subject to powdery mildew.

The Prussian Royal family hid their children in a cornfield when Napoleon invaded the country, and thus are seen as a symbol for hope.

Flowers have culinary use in salads and as garnishing. Often used as part of tinctures.

Family: Asteraceae (Daisy).

Closely Related Species: Centaurea macrocephala (Giant Knapweed); Centaurea montana (Mountain Cornflower).

Further Reading and References: Burke Herbarium Image Collection; Texas Cooperative Extension; and UMass Extension Guide to Cut Flowers.

Common Cornflower Questions

How tall are Centaurea Cyanus?

They typically reach a couple of feet in height (about 60 to 75 cm).

When do Centaurea Cyanus bloom?

Natively from the end of Spring through to the middle of summer. Garden grown cornflowers can have a prolonged blooming period, and can bloom earlier when grown as a perennial in warmer climates.

How do you Care for Cornflowers?

Easy to look after, supply a little water when the soil is in danger of drying out, deadhead following blooming. Plants do well in average soils but you may wish to use a balanced (phosphourous based) flower fertilizer once a month if growing in pots or containers.

Close up of Centaurea Cyanus flower.
Centaurea Cyanus flower closeup by Peter Corbett; CC.

What does cornflower symbolize?

It is thought that this plant represents hope for the future. Because of this the flower has many traditional ties to central European countries politically.

I hope that you enjoyed this guide on how to grow Centaurea Cyanus. You may also enjoy the following growing guides: How to grow Aster plants and Tahoka Daisy in your garden.