How to Grow Corncockle: A Practical Guide from Seed to Flowers

Corncockle is a traditional cornfield wildflower with slender stems and lovely pink-purple flowers. It looks particularly good growing amongst cornflowers, poppies and other annual wildflowers, where the plants can weave naturally through one another.

It's also straightforward to grow from seed. Corncockle is an annual, so each plant completes its life cycle in one season, but if you allow some flowers to set seed you may find new plants appearing the following year.

Corncockle likes a sunny position and doesn't need particularly rich soil. In fact, it's perfectly suited to the sort of conditions you'd use for a cornfield wildflower display.

The flowers are useful for pollinating insects and work well in informal borders as well as dedicated wildlife areas.

One important thing to know is that corncockle seeds are poisonous if eaten, so don't grow it somewhere the seeds might accidentally be harvested with edible crops, and keep the seed away from children and pets.

Apart from that, it's a wonderfully uncomplicated wildflower. Sow it, give the young plants a little room and largely let them get on with it.

When to Sow

Corncockle can be sown in spring or autumn.

For spring sowing, March to May works well. I generally sow directly outside because the seeds are easy to handle and the plants don't need the extra attention of being raised under cover.

You can also sow from August to October. Autumn sowing follows the plant's natural cycle and often produces sturdy plants that get away quickly the following spring.

If you're creating a cornfield display, sowing Corncockle at the same time as cornflowers and poppies makes life considerably easier.

I will sow seeds on the same patch in both autumn and spring to give the best results and the longest flowering period.

How to Sow

Choose an open, sunny position and prepare the ground by removing weeds.

Rake the surface to produce reasonably fine soil. Wildflowers don't need luxurious ground, but young seedlings do need a chance to establish without immediately competing with a thick covering of weeds or grass.

Sow the seeds around 1cm deep, either in shallow drills or scattered more naturally through the area.

Cover lightly with soil, gently firm the surface and water if conditions are dry.

If you're growing Corncockle as part of a wildflower display, I don't sow the seeds in straight lines but scatter small groups through the planting and let the eventual display look a little more natural.

Keep the soil reasonably moist while the seeds germinate and the seedlings establish.

Thinning and Growing On

Once the seedlings appear, thin them if they're badly overcrowded.

Aim for around 15–20cm between plants. They don't need to be measured precisely, particularly in a wildflower area, but a little space helps plants branch and develop properly.

Keep weeds under control while the seedlings are small.

Once established, Corncockle grows quickly and needs very little attention. The plants produce slender upright stems and look particularly good growing amongst other annual wildflowers. They can become fairly tall, 

In an exposed garden, groups of plants tend to support one another. If you're growing just a few in a formal border, they may appreciate some support.

I generally prefer letting them lean naturally through neighbouring flowers rather than trying to keep every stem perfectly upright.

Watering and Feeding

Water young plants while they're establishing, particularly if spring conditions are dry.

Once established in the ground, Corncockle shouldn't need constant watering. Give plants a proper drink during prolonged dry periods and otherwise leave them to get on with it.

There's generally no need to feed Corncockle growing in the ground.

Rich soil and lots of fertiliser aren't necessary for a traditional cornfield annual and can encourage plants to make soft, lush growth.

If you're creating a wildflower area, keeping fertility relatively low also helps stop vigorous grasses and weeds from taking over.

This is another plant where doing less usually works perfectly well.

Flowering and Wildlife

Corncockle flowers during summer, producing attractive pink-purple blooms on tall, slender stems.

The flowers are visited by bees and other pollinating insects, making Corncockle a useful addition to a mixed wildlife planting.

I think it works best alongside other wildflowers rather than planted entirely on its own. Cornflowers, poppies and oxeye daisies can give you different flower shapes and flowering periods, providing more variety for visiting insects.

If you want to prolong flowering, you can remove some faded blooms.

For a more natural wildlife display, leave some flowers alone so they can produce seed.

You don't have to choose between a perfectly tidy garden and one that's useful for wildlife. Deadhead a few plants and leave a few others to complete their life cycle.

Saving Seed and Self-Seeding

Corncockle is an annual, so the original plants won't return the following spring.

However, plants can self-seed if you allow the seed pods to mature.

Leave some flowers on the plants towards the end of the season. Once the seed heads have ripened and dried, you can either allow the seeds to fall naturally or collect them for sowing elsewhere.

If you're collecting seed, store it somewhere cool and dry until you're ready to sow.

Remember that Corncockle seed is poisonous and must not be eaten. 

Self-sown seedlings may appear in slightly unexpected places the following year. That's part of the charm of a wildflower patch as far as I'm concerned.

If they appear somewhere you really don't want them, they're easy enough to remove while young.

Common Problems

Slugs and Snails

Slugs and snails can damage young seedlings, particularly during damp spring weather.

Keep an eye on new growth until the plants are established. Larger plants are generally much better able to cope with a little damage.

Poor Germination

Cold, waterlogged soil or very dry conditions can reduce germination.

Prepare the ground before sowing and keep spring sowings reasonably moist until seedlings are established.

Plants Becoming Tall and Floppy

Corncockle naturally produces tall, slender stems.

Plants grown together amongst other wildflowers usually support one another reasonably well. Very rich soil can encourage softer growth, so don't feed them unnecessarily.

Few Flowers

Too much shade can reduce flowering.

Corncockle performs best in an open, sunny position. Very rich soil can also produce plenty of growth without necessarily improving the flower display.

Aphids

Aphids may occasionally gather around tender shoots.

Small populations are rarely worth worrying about. In a wildlife garden, predators such as ladybirds and hoverfly larvae will often arrive to help.

Plants Disappearing After Summer

That's completely normal.

Corncockle is an annual, so the plants die after flowering and setting seed. Leave some seed heads to mature or collect seed yourself if you'd like to grow it again next year.

Corncockle is a lovely plant for giving a wildlife area that traditional cornfield feel. It doesn't need rich soil, complicated feeding or endless attention. Sow it alongside a few other annual wildflowers, leave some seed heads at the end of summer and let the planting become just a little bit untidy. That's often when a wildlife patch starts looking its best.