Blue cornflower is a pretty garden flower with heads of bright blue-violet flowers on tall, slender stems. The flowers are thistle-like and it is part of the thistle branch of the daisy family.
Each flower is made up of dozens of tiny tube-like florets, the flower having a rounded and slightly shaggy shape, held airily over narrow grey/ green leaves. Not many flowers give such a piercing blue colour. Cornflower is aptly named because it was a common weed of cornfields and cultivated ground, but it has disappeared from cornfields in modern times. The seed was harvested, along with barley or wheat, and as it declined, the seed source dried up, too. If it is seen outside a garden now, it is likely to be a garden escape, because it produces large quantities of seeds and these can be carried in mud and on footwear.
If it was once a cornfield weed and can manage as a garden escape, it naturally follows that it is a very easy flower to raise and grow. It is a hardy annual, meaning it can live its life outdoors - even through winter weather and it is an annual because it completes its life cycle of seed to seed in a single growing year.
It can be sown in late summer or early autumn to flower beginning in late spring, or it can be sown in spring to flower in mid-summer. Seeds are widely available and, to the standard blue kinds, white, pink and purple forms, often sold as mixed colours, have been added. The seeds can be sown when the plants are to flower. Cornflower is often sold as part of wildflower mixes, as it is a reliable, undemanding flower. Cornflower likes an open sunny position in light, well-drained soil. Very rich, fertile soil makes leafy, soft plants that do not flower as well.
Young plants grown over winter must have freely drained soil or the roots may rot. Weed competition results in scrawny plants and weeds should be removed when small to avoid disturbance of the cornflower roots. If the young plants, themselves, are too crowded, excess seedlings can be carefully removed.
Apart from forms in a variety of colours, the plant breeders have selected forms with shorter stems. The basic type can be 90 centimetres tall and has a tendency to flop over, the slender stems originally being supported in the cornfield by the upright stems of wheat or barley.
Some of the selected varieties are very short, just 20 centimetres, but, while they stay upright, they lack some of the elegance of the original flower.
Cornflowers make a good cut-flower, lasting a few days in water and offering a breath of summer indoors.