Cornflower: sowing, flowering time & uses

Katja
Katja
Katja
Katja

I study landscape ecology and through my studies have discovered a love for plants. Plants are not only beautiful, but also have countless fascinating survival strategies. To bring a bit of nature into my home as well, I nurture my houseplants and herbs on every possible windowsill.

Favourite fruit: rhubarb and all kinds of berries
Favourite vegetables: onions and garlic

Cornflowers not only provide food for many insects, but they are also popular in the kitchen and can be used to treat a wide variety of ailments. Find out more about this valuable plant and how to go about sowing and planting cornflowers in your own garden.

Blue cornflowers
In classic cornflower blue, the cornflower usually blossoms at the edge of grain fields [Photo: HeiSpa/ Shutterstock.com]

Cornflowers (Cyanus segetum) are known for their brilliant cornflower blue flowers, but they can also bloom in other colours. Read on to discover some of the most beautiful cornflower varieties and get helpful tips on cornflower care, sowing cornflower seeds and more.

Cornflower: flowering time, origin and properties

Most people are familiar with cornflowers’ brilliant blue blooms. They are often found together with poppies in parks or in flower borders along grain fields. The showy yet odourless flowers appear from May to September. Cornflower blossoms are also a favourite among pollinators. Unfortunately, due to intensive farming, the cornflower, also known as bachelor’s button, is now classified as an endangered species that is rarely found in the wild. Because of this, they are protected under the Wildlife and Countryside Act 1981.

A bee rests on the cornflower blossom
The cornflower attracts bees and other insects [Photo: guentermanaus/ Shutterstock.com]

Cornflowers are annuals that originate from the Mediterranean region. With the help of man, they have spread further into Central, Eastern and Western Europe. They belong to the daisy family known as Asteraceae, but were formerly a member of the knapweed family, Centaurea. Cornflower leaves are covered with fluffy hairs and come in various different shapes. Whilst upper cornflower leaves are usually full-margined and lanceolate, the lower leaves are serrated and divided. Cornflowers grow upright and can reach up to 90cm tall. There are plenty of different varieties available to choose from. Since cornflowers contain things like flavonoids, tannins and bitter substances, they used to be used as a medicinal plant. Today they are sometimes still used in cooking as a garnish.

Are cornflowers perennial? No, cornflowers are annuals, meaning they do not come back again the next year. However, in suitable locations, cornflowers reproduce by self-seeding and new plants emerge the following spring.

Chicory flowers
The flowers may be remotely similar, but the habitus of cornflower and chicory is not at all [Photo: Hana Stepanikova/ Shutterstock.com]

Confusing cornflowers: other members of the knapweed family look quite similar to cornflowers. Common chicory (Cichorium intybus), for example, also looks a bit like cornflowers. However, if you look at a chicory plant up close, you will notice it has small, differently shaped flowers.

Beautiful cornflower varieties

Garden varieties of cornflowers have impressive, diversely coloured blossoms. Here are a few of our favourite cornflower varieties:

  • Cyanus segetum ‘Blue Ball’: this variety reaches up to 80cm high and has fuller-looking, double flowers that come in a classic cornflower blue. However, double varieties like ‘Blue Ball’ are not as bee-friendly.
Blue double cornflower
The flowers of some varieties are more double [Photo: brackish_nz/ Shutterstock.com]
  • Cyanus segetum ‘Classic Romantic’: get multiple colours in one flower with the ‘Classic Romantic’ variety. The flowers are pink and white. Their growth height is 60 – 90cm.
Centaurea cyanus 'classic romantic' pink and purple flowers
This is what the variety ‘Classic Romantic’ can look like [Photo: spacetree/ Shutterstock.com]
  • Cyanus segetum ‘Red Lola’: ‘Red Lola’ is a bright pink cornflower variety which can grow up to 80cm tall.
Centaurea cyanus, pink cornflower blossoms
There are also cornflowers in pink [Photo: simona pavan/ Shutterstock.com]
  • Cyanus segetum ‘Black Ball’: the dark, red purple blooms of ‘Black Ball’ cornflowers appear almost black. At about 60cm tall, this variety is smaller than most other cornflower varieties.
Centaurea cyanus 'black ball' flowers
This cornflower is actually red, but looks almost black [Photo: Edita Medeina/ Shutterstock.com]
  • Cyanus segetum ‘Blue Boy’: ‘Blue Boy’ cornflowers bloom in a vibrant blue and have full flowers. They grow 50 – 70cm tall.
Centaurea cyanus 'blue boy' flowers
Whether classic in blue or also in red, pink or white, with the cornflower there is something for everyone

Sowing and planting cornflowers

Cornflowers are beautiful, low-maintenance garden plants. The easiest way to grow your own is by sowing cornflower seeds.

Where to plant cornflowers

Cornflowers like sunny spots on moderately fertile, loose and well-drained soil that is slightly calcareous. They can also cope with sandy soils.

Cornflowers in mixed culture: common poppies (Papaver rhoeas) and daisies (Leucanthemum) are excellent cornflower companion plants both visually and in terms of site requirements. Since cornflowers also attract beneficial insects, they are often included in seed mixtures for flower meadows.

Cornflower in a meadow with other wild flowers
Together with the poppy, the cornflower is often seen in wild meadows [Photo: ON-Photography Germany/ Shutterstock.com]

How to sow cornflowers

Cornflowers are not perennial, so you will need to reseed them each year, unless you leave them to self-seed. Sowing cornflower seeds is very simple:

  • Sow seeds between March and April
  • If sown later, the plants will be smaller
  • Sow in small groups of about 3 – 10 plants
  • Keep a planting distance of about 30cm
  • Cornflowers need light to germinate, so only cover the seeds with a light layer of soil
  • Cornflower seeds will germinate after about 14 days

Growing cornflowers in pots: it is easy to keep cornflowers in pots. However, since cornflowers grow deep roots, the pot needs to be at least 30cm tall. A drainage layer is absolutely necessary to ensure the water can drain away. You can make this from shards of clay, expanded clay or pebbles. As for soil, use a high-quality potting soil mixed with one-third sand. Our Plantura Organic Flower Compost is ideal as a base, as it has a high humus content and retains water very well. It is also entirely peat-free and, due to its natural ingredients, it is safe for pets and garden animals. Our compost also contains expanded clay, which benefits cornflowers by increasing permeability. Mixing a bit more expanded clay into the compost will help your cornflowers feel even more at home in your garden.

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Cornflower care

Since cornflowers are low-maintenance plants, there is not much more to do once they have germinated successfully in a suitable location.

Cornflowers usually do well in somewhat nutrient-poor conditions and do not require additional feeding. Fertilising can be useful in certain circumstances, such as when the cornflowers are very old or in very poor soil, pots, or recycled potting soil. In these cases, use an all-purpose fertiliser, such as our Plantura All Purpose Plant Food. Our fertiliser supports plant growth and promotes an active, healthy soil life. For cornflowers, a low dosage is sufficient.

By the way, overfertilisation manifests as a lack of flowering or limp leaves. Besides spider mites and aphids, overfertilising is the most common cause of damage to cornflowers.

Blue cornflower blossom
Here the sterile marginal flowers, which only have a presentation purpose, are easy to see [Photo: Daniel Alexander Schmitt/ Shutterstock.com]

Tip: the flower heads ofplants from the daisy family consist of many small individual flowers, which are often mistaken for petals. The outer floral ring is sterile; only the central tubular flowers are fertile.

Only water cornflowers during prolonged periods of drought or in midsummer. Avoid waterlogging and make sure that any excess water can drain away, especially if you have potted cornflowers.

Pruning is not necessary. However, removing any withered inflorescences will coax your cornflowers to bloom again.

Cornflower seeds
The seeds can be harvested from the flower head at the end of summer [Photo: guppyss/ Shutterstock.com]

Are cornflowers hardy? Cornflowers are not hardy. They are annual plants that do not come back the following year.

Propagating cornflowers

The best way to propagate cornflowers is by sowing cornflower seeds. You can collect the seeds from the flowers themselves. After flowering and successful fertilisation, the pappus forms. This looks furry and forms on the fruit. Cornflower seeds can be harvested from this point on and should be stored in a dry place until you sow them the next spring.

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Are cornflowers edible?

Cornflower blossoms are edible and work great as a garnish on dishes and salads. They are not poisonous and, in the past, were even used for healing. When preparing cornflowers, do not use the entire flower; it is better to pluck out the individual small flowers. Unlike the flowers, the calyx and the leaves are not spicy, but rather bitter.

Cornflower properties and uses

Previously, cornflowers were used to treat digestive problems, insect bites and chronic coughs because of their active ingredients such as mucilage and bitter substances. Today, cornflowers are not particularly important in medicine. To use cornflowers for medicinal purposes, you will need the dried seeds. A tincture made from cornflower blossoms and many other blue-flowering herbs is also said to help with restlessness. Cornflower tea is made from dried or fresh cornflower blossoms.

Cornflower seedling in a pot
After about two weeks the cornflower seedlings show themselves [Photo: Tamara Lopes/ Shutterstock.com]

Borage (Borago) is also a component of blue-flower tinctures. Find out everything you need to know about planting, caring for and harvesting borage in our linked article.

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