Genus Centaurea, commonly known as cornflower or bachelor’s button, is native to Europe. In the past, it often grew as a weed in cornfields with double 1 1/2-inch blooms that resemble miniature carnations hence its name. The cornflower plant is easy to grow by seed and makes a long-lasting cut flower, even retaining the blue color when dried.
Cornflowers are sometimes referred to by their nickname, “bachelor’s button” due to an old practice when men wore a cornflower in a buttonhole of their suit, indicating they are in love or they were ready for courting.
Cornflower is a member of the Asteracea or Compositae family, which is a large and widespread group of plants that includes sunflowers, daisies, and asters. The genus is Centaurea, which includes both annual and perennial varieties. Cornflowers readily grow from seed and will thrive when sown indoors in pots 4 weeks before a frost-free date, then transplanted, or outdoors directly in the garden.
Called ‘Bluet’ in England and ‘Bluebonnet’ in Scotland, in North America Cornflowers are sometimes called Ragged Robin, or Ragged Sailor because of the shaggy petals. They are one of the few true blue flowers that are also edible, imparting a sweet cucumber like taste. In the garden, they are visually stunning planted with brightly colored Nasturtiums, Marigold and California Poppies. In a vase, they blend well with Snapdragons, Sweet William and Love-in-a-Mist (or Nigella).
Cornflowers are often used as a boutonniere in weddings, and because of their popularity, have been bred to produce plants for a wider range of blossom colors, including white, pink, red-purple, deep burgundy (sometimes called black) and the crisp blue which is the only true natural color.
Cornflowers thrive in U.S. Department of Agriculture plant hardiness zones 2 through 11. They prefer to grow in an open, sunny location and can tolerate poor soil, yet prefer rich loamy garden soil that has been enriched with phosphorus, which gives an extra boost to fruit and flowering plants. Dig a little fertilizer into the soil at the start of the growing season, and again mid-summer.
Major Types
Standard Annual Cornflower
Annual cornflowers (Centuarea cyanus), also called bachelor’s buttons or blue bottle, are spring through summer bloomers. In addition to the traditional blue cornflower plant color, you can find them in violet, pink, lavender and white shades, says Fine Gardening. The flowers are 1 1/2 inches across with ragged petals.
Standard annual varieties grow 2 1/2 to 3 feet tall and spread 6 to 12 inches wide. They may topple over in the wind as they reach their full height, requiring you to stake them. Plant annual cornflowers in cutting gardens and cottage gardens or add them to meadow gardens for a wildflower look. Although considered an annual, these cornflowers tend to self-seed from year to year.
Dwarf Annual Cornflower
Smaller varieties of annual cornflowers are suitable for planting in flowerbeds and containers. ‘Dwarf Blue Midget’ (Centaurea cyanus ‘Dwarf Blue Midget’) sports flowers of true blue color. It grows only 6 to 12 inches tall, blooming from June through September. ‘Florence Mix’ (Centaurea cyanus ‘Florence’), another compact cornflower, tops out at 6 to 12 inches tall. In addition to blue flowers, ‘Florence Mix’ contains shades of near white, pure white and pink. It blooms from June through August.
The Perennial Cornflower
Perennial cornflower (Centaurea montana) is a showy, 2-foot wide and tall plant that blooms from May to June. According to the Missouri Botanical Garden, it displays single 2-inch fringed violet blue flowers with purple to reddish centers. Hardy in U.S. Department of Agriculture plant hardiness zones 3 through 8, perennial cornflower is also called mountain bluet. Spreading by underground stolons, perennial cornflower rapidly forms colonies. Its bright blue flowers make it a good addition to the cutting or cottage garden.
Cornflowers typically call up visions of sky blue flowers waving in a summer breeze. Although both annual cornflower (Centaurea cyanus) and perennial cornflower (Centaurea montana) typically sport bright blue blooms, they also appear in an array of pink, lavender, violet, purple or white. Cornflowers range in height from tall 3-foot varieties to dwarf cultivars only 6 inches high.
Types of Cornflowers
‘Blue Boy’
This classic variety boasts a vibrant, true blue color that perfectly captures the traditional image of a cornflower.
- Characteristics: Deep blue, single blooms.
‘Dwarf Blue Ball’
A compact variety ideal for borders or containers.
- Characteristics: Deep blue, semi-double blooms.
‘Red Boy’
A stunning variety with vibrant red flowers, adding a splash of color to any garden.
- Characteristics: Rich red, single blooms.
‘Double Click’
Features large, double blooms in a range of colors, including blue, pink, and white.
- Characteristics: Double blooms, various colors.
‘Blue Diadem’
Showy blooms with large, deep blue petals and a slightly darker center.
- Characteristics: Large, deep blue blooms.
‘Jubilee Gem’
Features large, deep blue double flowers with frosted white edges.
- Characteristics: Double blooms, deep blue with white edges.
‘White Dwarf’
A compact variety with pure white flowers, adding a touch of elegance.
- Characteristics: White, single blooms.
‘Pink Sensation’
Delicate pink blooms, perfect for a romantic garden setting.
- Characteristics: Soft pink, single blooms.
‘Black Ball’
A unique variety with deep maroon or almost black flowers.
- Characteristics: Deep maroon/black, single blooms.
‘Classic Mix’
A colorful mix featuring a variety of colors, including blue, pink, red, and white.
- Characteristics: Mixed colors, single blooms.
‘Double Click Rose’
Features large, double blooms in a beautiful shade of rose pink.
- Characteristics: Double blooms, rose pink.
‘Blue Ball’
A classic blue variety with semi-double blooms.
- Characteristics: Semi-double blooms, deep blue.
‘Amethyst’
Features soft, lavender-blue flowers with a delicate appearance.
- Characteristics: Lavender-blue, single blooms.
‘Dwarf Blue’
A compact variety with vibrant blue flowers, ideal for smaller gardens.
- Characteristics: Deep blue, single blooms.
‘Frosted Pearls’
Unique blooms with a mix of colors and textures, resembling frosted pearls.
- Characteristics: Mixed colors, unique texture.