How to grow cornflowers
Advice on growing and caring for cornflowers, in our Grow Guide.
Plant Size: Height: 100 Spread: 30 |
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 along with corn poppy, corn marigold and corncockle. As a result of pesticide use, it's now rarely seen in the wild. But due to its popularity with pollinators, it's sold in wildflower mixes for wildlife gardens.
The original species is beloved for its deep cornflower blue blooms, 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.
How to grow cornflowers
Grow cornflower plants 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. 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.
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.
How to plant cornflowers
Ideally, sow cornflower seeds directly where plants are to flower from March to May, 0.5-1cm deep. Sow in drills, or you can simply scatter the seed and then rake lightly to cover with soil. Thin the resulting seedlings to 10-15cm apart. Making several sowings throughout spring will ensure a succession of flowers during the summer.
If ground or weather conditions do not permit outdoor sowing, you could sow cornflowers in pots in general-purpose, peat-free potting compost mixed with a third by volume of coarse grit. Place under cover in an unheated greenhouse or polythene tunnel and harden cornflower seedlings off before planting out in late spring, spaced 15cm apart. Shorter-growing varieties are best for pots as taller ones tend to flop without support. Cornflowers can also be sown in pots from August to October and planted out in autumn or grown on, overwintered in pots and planted out the following spring.
How to care for cornflowers
Cornflowers bloom for around 10-12 weeks, which isn’t as long as many summer-flowering bedding plants. 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
Cornflower plants are annuals and 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, or in the autumn.
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
Where to buy cornflowers
Frequently asked questions
Do cornflowers come back every year?
Cornflowers are annuals, so they do not come back every year. Instead, they complete their life cycle within one growing season. But plants may self-sow their seed, which will bloom the next year. Cornflower plants are not invasive and any unwanted seedlings can easily be pulled out.
What is cornflower tea good for?Cornflower blooms are edible – the petals make lovely garnishes to salads and other dishes, and they are widely used in teas to add colour. Cornflower tea is said to aid digestion and promote calm. But you should avoid if you are pregnant, breast-feeding or allergic to other members of the Asteraceae family, and check with a qualified healthcare professional before eating or drinking cornflower, especially if you have a medical condition or take medication.
