Cornflowers are a pretty annual wildflower that was once commonly seen growing natively throughout Britain's rural meadows. Unfortunately, as with many species of wildflowers, the cornflower is now rarely seen in the wild. It has become almost extinct in rural landscapes thanks to modern agricultural methods.
Fortunately, the plant is easy to grow at home and is hardy to a wide variety of temperatures, so most people are able to grow this attractive, easy-care flower in their own garden.
Bachelor’s Button Overview
|Scientific Name||Centaurea cyanus|
|Type||Annual flowering plant|
|Common Names||Cornflower, Bachelor’s button, Bluebottles, Witch bells, Ragged robin|
|Height||Up to 3 feet tall|
|Pests||Mealybugs and aphids|
Centaurea cyanus ‘Black Magic’
This cornflower features striking flowers in an unusual deep purple-maroon color. They look especially stunning in cut flower bouquets. Growing to heights of between 2 and 3 feet, this dramatic wildflower makes a statement in any garden. The flowers are also edible and can be used for decoration in salads or desserts.
Centaurea montana - Mountain Blue
This is the perennial cornflower, which grows to 2 feet in height with a similar spread. It has a shorter blooming period than the annual cornflower, typically flowering in early spring until early summer. Its flowers are purple-blue, though other cultivars exist with a range of flower colors. It is hardy from USDA growing zones 3 through 8.
Centaurea montana ‘Gold Bullion’
This is a cultivar of the perennial mountain cornflower, which has stunning unusual colored flowers and foliage. The leaves of the plant are a golden yellow, while the flowers are a contrasting pale purple with dark red centers. It grows between 1 and 2 feet in height.
Centaurea montana ‘Amethyst Dream’
This dramatic perennial cornflower has deep purple flowers that bloom in the middle of summer. It grows to around 20 inches tall.
Centaurea montana ‘Black Sprite’
Another perennial cornflower, this variety features unusual flowers in dark purple and black. The blooms are star-shaped, growing atop of stems that reach up to 35 inches in height.
Centaurea cyanus ‘Dwarf Blue Midget’
This dwarf version of cornflower grows to between 6 and 12 inches tall, making it ideal for growing in containers or flowerbeds. It features blue flowers that bloom from June to September.
Centaurea cyanus ‘Florence Mix’
This is another dwarf version of cornflower, reaching a maximum height of 12 inches. It blooms from June to August in a variety of colors, including pink, white, and blue.
Centaurea cyanus ‘Blue Boy’
This compact variety also tops out at 12 inches tall. It features double flowers that resemble thistles in intense shades of blue. It blooms in August and September and is especially attractive to bees and butterflies (Gardeners World).
Caring for Your Bachelor’s Button
Cornflowers can adapt to both dry and moist conditions, becoming drought-tolerant once established. If you get fairly regular rainfall throughout spring and summer, you may find that your cornflowers grow well without you having to water them at all. On the other hand, periods of prolonged dry weather will mean that you need to intervene and give your cornflowers a few substantial drinks.
Though cornflowers are drought-tolerant, they will flower more profusely if their soil is kept moist during the growing season. They don’t do well in soggy soil, so be sure to only water once the top layer of soil has dried out to prevent overwatering. The type of soil the cornflowers are planted in will affect how often they need to be watered.
Cornflowers need well-draining soil and can grow in poor quality soil lacking in nutrients, but grow best in soil that is high in organic matter. Before planting, work compost into clay or sandy soil to help create a balanced environment that will be both well-draining but also have some capacity to retain moisture.
Though cornflowers are drought-tolerant, they prefer moist soil, and the addition of organic matter into the soil will help to achieve this without making it boggy. A moist soil will help to contribute to a more prolific bloom and a longer flowering period. Cornflowers are not bothered between alkaline, neutral, or acidic soils and will grow well in either.
Cornflowers need full sun and will not tolerate full shade just like other wildflowers like foxgloves, hydrangeas. Plant cornflowers ideally in south-facing aspects where they can benefit from sunlight all day. You should aim to ensure they receive 6 to 8 hours of light each day, though if they are planted in partial shade, position them so that they have full sun in the morning and are shaded in the middle of the afternoon. This will give the plant some relief from the heat at the hottest point of the day, though they usually tolerate heat well in all but the most extreme circumstances. Too much shade will cause the plants to flop over, so watch out for this sign that your cornflowers need more sun.
Cornflowers are very hardy plants and are suitable for planting in USDA growing zones 2 through 11. The plant is not frost tender and performs as a reliable annual. It is tolerant of both cold and hot temperatures, making it a great plant to grow in a wide variety of climates. There are some varieties of cornflower which grow as perennials, though these are not the common cornflower.
If you’re a lazy gardener, you can leave your cornflowers to their own devices, and they will do just fine without pruning. However, if you like to get involved with your plants, then there are pruning methods you can use to get the best out of your plants.
To encourage a bushier growth, you should pinch back cornflower stems late in winter or early spring. This will result in a more dense looking plant, and it will also help to promote stronger flowering. To pinch back your cornflowers, sift through them using scissors or your fingertips, removing the top part of the stem and the top set of leaves. Make the cut at the point where the next set of leaves are joined to the stem.
Deadheading is also a pruning method you can implement with your cornflowers. Rather than just removing the spent flower itself, remove the stem. The flower is attached to back to the next set of leaves. Deadhead your cornflowers throughout the blooming period whenever you spot a spent flower; this will lead to more blooms and an extended flowering period.
Deadheading will also prevent the plants from self-seeding, so if you did want to encourage this, you would need to leave a few spent flowers untouched. The seeds that develop from these flowers also make an important source of food for wild birds.
Cornflowers grow best from seed. You can sow them outside directly into the ground soil, or sow them indoors for transplanting outdoors later on. Cornflower seeds can be sown outside anytime during spring and summer, so long as the final frost has passed. Seeds sown between March and May will produce flowers in August and September, while those sown in August and September will flower early in the season the following year.
In mild climates, you can sow cornflower seeds outdoors during winter. To sow the seeds, spread them thinly on moist soil and cover them with a thin layer of soil. The soil should be kept moist for the seeds to germinate. Once seedlings have appeared and reached a size that is big enough to handle without causing damage, you can thin out the seedlings so that there is a gap of between 5 and 10 inches separating each plant. This will ensure there is enough space for the cornflowers to grow.
Remove any weeds that appear amongst the cornflowers as these will inhibit your plant's growth. Growing cornflowers from seed are very easy, with success rates high. They grow quickly and should reach their full size in just 3 or 4 months. Cornflowers are also prolific reseeders, and you may find that you have more of these plants growing in your garden each year without having planted any seeds yourself.
If you wish to prevent the plant from self-seeding, then you simply need to deadhead the spent flowers, as this will ensure they don’t have the opportunity to turn to seed. If you’d like to encourage self-seeding, then leave spent flowers to develop into seed, which will disperse themselves in the wind, via birds, or as they drop to the ground.
Cornflowers produce pretty flowers in deep blue, blooming for several months from early spring to mid-summer. The flowering period can be extended to late summer if the flowers are deadheaded. Cultivars of the plant can produce flowers in shades of lavender, pink, and white, and they make excellent cut flowers. They are also commonly used for making dried flower displays. The flowers are particularly attractive to birds and butterflies.
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