Cornflower

How to recognise it

Growth habit

Annual, 30–80 cm, with slender, branched, grey-green and slightly woolly stems.

Leaves

Narrow, linear to lance-shaped, 5–10 cm, grey-green and slightly felted; the lower leaves sometimes have a few lobes.

Flowers

Heads of 2–3 cm with bright blue, funnel-shaped outer florets and purplish-blue tubular florets in the centre; June to August.

Bracts

The bracts beneath the head are green with a silvery-white to brown, finely toothed fringe.

Seed

A smooth, oblong nutlet of 3–4 mm with a short tuft of bristles.

Look-alikes

Perennial cornflower is a garden perennial with broader leaves and larger, more loosely frilled heads. Chicory also has blue flowers, but with flat strap-shaped florets and no funnels.

Flowering: June–August · Pruning: July and September

Why grow it?

• Rich in nectar: bees, bumblebees, hoverflies and butterflies visit the flowers all summer.
• The bracts beneath the flower head also produce nectar outside the flower, which attracts ants and small beneficial wasps.
• Finches such as the goldfinch eat the ripe seed in late summer.
• Ideal for quickly bringing a patch of bare soil into flower, together with other cornfield flowers.
• A lovely cut flower; the blue petals are edible and are used to decorate salads and cakes.

Cornflower: where does it grow best?

• In the wild: cereal fields, field margins, verges and fallow ground, mainly on sand and loam.
• In the garden: full sun is essential; in shade it flops over and flowers poorly.
• Poor to moderately fertile, free-draining soil; on rich soil it grows tall and floppy.
• It needs bare, loosened soil to germinate; in dense turf it will not establish.

Goes well with

• Common poppy: The classic cornfield duo: red next to blue.
• Corncockle: Purplish-pink flowers among the cornflowers; another rare cornfield flower.
• Scented mayweed: Small white flowers with a yellow centre that make the colours glow.
• Corn marigold: Golden-yellow flowers on the same poor, bare soil.

Cornflower: when and how to plant it?

1. Buy seed of native origin from a seed merchant or native plant nursery. Never dig up plants from the wild.
2. Sow in September–October for sturdy plants that flower early, or in March–April for later flowers.
3. Clear the soil of weeds and loosen it, scatter the seed thinly and rake it in lightly, about 1 cm deep.
4. Thin to 15–20 cm between plants, or sow in a mixture with other cornfield flowers.
5. Water until the seedlings are well up; after that only during long dry spells.
6. Lightly cultivate the soil every autumn: that way cornflowers keep coming back in your garden.

Care

Watering

Only during germination and long dry spells in spring.

Feeding

Not needed: on poor soil the stems stay sturdy.

Deadheading

Cut off faded heads regularly for a longer display; leave the last ones for seed.

Support

In a windy spot support the stems with a few twigs, or sow more densely so the plants hold each other up.

Self-seeding

Let some plants seed in late summer and loosen the soil in autumn: it will come back by itself.

Tip: Sow cornflowers in autumn: plants that come through the winter are sturdier and flower weeks earlier than a spring sowing.

Pruning and mowing

Pruning months: July and September.

When: Deadhead in July; clear the dead plants in September.

How:

• In July cut faded heads back to just above a side bud; new flowers will follow.
• From August let the last flowers set seed, for next year and for the birds.
• In September pull up or cut down the dry plants once the seed has dropped, and lightly loosen the soil.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

The only method. Sow in autumn or spring on bare soil. You can collect ripe seed yourself in August and store it dry until sowing.

Cornflower: how does it get through the winter?

Hardy to −15 °C: protect young plants.

• As an annual, the plant dies after setting seed.
• Autumn-sown seedlings overwinter as small grey rosettes and can take a fair amount of frost.
• Late seed heads still offer birds some food in autumn.

Diseases and pests

• Flopping: Caused by soil that is too rich or too much shade. Sow more densely or in a poorer, sunny spot.
• Powdery mildew: Greyish-white powder on the leaves in late summer, at the end of the season. Clear affected plants.
• Aphids: On the stem tips; ladybirds and hoverfly larvae usually deal with them.
• Disappears after a few years: There is no bare soil left for germination. Cultivate a patch of ground in autumn and sow again.

Through the year

• March: Sow on bare soil.
• April: Sow; thin out seedlings.
• May: Rapid growth; add support if needed.
• June: First flowers.
• July: Full flower; deadhead faded heads.
• August: Last flowers; let seed ripen and collect it.
• September: Clear dry plants, loosen the soil and sow.
• October: Sow for flowers next year.
• November: The small rosettes overwinter.

Did you know?

• In France the cornflower (Bleuet de France) has been the symbol of remembrance for war victims and veterans since the First World War, much as the poppy is in Britain.
• The cornflower is the national flower of Estonia.
• The species name cyanus comes from the Greek word for dark blue.