Cornflower (Centaurea cyanus) is an easily grown hardy annual wildflower that is quick to grow and blooms in summer, bearing masses of pretty, ruffled flowers on slender wiry stems. While not native to the UK, it was introduced from the Mediterranean thousands of years ago and is considered 'naturalised'.
It used to be a common sight in arable fields – indeed its common name came about because it was once considered a weed of cornfields, along with corn poppy, corn marigold and corncockle. Thanks to pesticides, it's now rarely seen in the wild but, due to its popularity with pollinators, it's sold in wildflower mixes for wildlife gardens. Cornflower blooms are edible, too, and the petals make lovely garnishes to salads and other dishes.
The original species of cornflower is beloved for its deep blue flowers, but there's now a wide choice of named varieties in different shades of blue, as well as pink, maroon, and white. Cornflowers are upright in habit, with plant height ranging from 30cm up to 120cm. The taller varieties make good cut flowers and cornflowers are an easy-to-grow addition to a cutting garden patch. Blooms are produced for up to three months in summer and, being annual, cornflower completes its life cycle within one growing season. Plants may self-sow their seed to bloom the following year, though cornflower is not invasive, and any unwanted seedlings are easily pulled out.
Cornflowers are easy for children to grow, either on their own or mixed with other cornfield annuals. Sow seed directly onto the soil, lightly rake over and wait for them to flower within around 10 weeks.
How to grow cornflowers
Grow cornflowers in sun and well-drained soil, sowing seed directly into weed-free ground or into pots, in spring. Thin out the resulting seedlings. After that, little care is needed apart from deadheading to encourage more blooms.
Where to grow cornflowers
Grow cornflowers as a gap-filler in any bare spots in borders, as part of a seed mix to create an annual flowering meadow, or in pots. Well-drained soil is best, and sun for at least half the day. Cornflowers do best in soil with low fertility so there's no need to add fertilizer or organic matter.
Cornflowers in pots need a general-purpose , peat-free potting compost mixed with a third by volume of coarse grit. Shorter-growing varieties are best for pots as taller ones tend to flop without support. Be aware that cornflowers bloom for around 10-12 weeks, which isn’t as long as many summer-flowering bedding plants.
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How to plant cornflowers
Ideally, sow seeds directly where plants are to flower. Otherwise sow in seed trays and harden them off before planting out in spring, spaced 15cm apart.
How to care for cornflowers
Remove faded flower heads to encourage more blooms to form. Once flowering is over, you can pull up and compost the plants, or leave them to self seed and provide food for birds such as goldfinches.
How to propagate cornflowers
Cornflowers usually self-seed readily, but if you want to save the seed, collect it from the faded flowers. Store the seed in an envelope and sow from early spring to early summer, 0.5-1cm deep, either in drills, or simply by scattering the seed and lightly raking to cover with soil. Thin the resulting seedlings to 10-15cm apart. Making several sowings throughout spring will ensure a succession of flowers through summer.
If ground or weather conditions do not permit outdoor sowing, an alternative is to sow in modular trays or small pots under cover in an unheated greenhouse or polythene tunnel.
Pests and diseases
Cornflowers are generally trouble-free to grow.
Advice on buying cornflowers
- Cornflower seeds are widely available: as separate colours in individual named varieties, in a mixture of colours or as part of a cornfield annual wildflower seed mixture
- Make sure you choose the right flower colour and height for your display, as these can vary depending on variety