The Centaurea genus includes a number of annual and perennial species that are commonly known as cornflowers or bachelor's buttons. Centaurea montana is a popular perennial species, closely related to traditional cornflower (which is an annual plant), and often referred to as mountain cornflower, perennial cornflower, perennial bachelor's button, or mountain bluet.
Native to Europe, the mountain cornflower is a clump-forming plant with gray-green lance-shaped leaves. The flower's buds resembling tiny pineapples and open into charming flowers that have long blue petals with a lacy texture and reddish-purple centers. There are also cultivars available with white petals or a purple so deep that it is almost black.
Mountain cornflower is usually planted in spring, though potted nursery specimens can be planted any time of year in the proper USDA hardiness zone. A small potted specimen may take a full year or two to become established, but then will colonize nicely and may live for 15 years or more.
|Botanical Name||Centaurea montana|
|Common Names||Mountain cornflower, perennial cornflower, perennial bachelor's button|
|Plant Type||Herbaceous perennial|
|Mature Size||1–2 ft. tall, 12–18 in. wide|
|Sun Exposure||Full sun|
|Soil Type||Dry to medium moisture, well-drained soil|
|Soil pH||Neutral to acidic, alkaline|
|Bloom Time||Late spring, early summer|
|Hardiness Zones||3–8 (USDA)|
Mountain Cornflower Care
Mountain cornflower is an easy-to-care-for varietal and will do well in almost any well-draining soil when planted in a sunny location. Little care is required, though you may need to remove volunteer seedlings or divide the plant every few years to prevent it from spreading too vigorously.
No doubt, the outstanding feature of this plant is its delicate flowers. They display a fine texture that can either be appreciated in its own right or set off against flowers of different colors or coarser texture to create a striking contrast. Deadhead the blooms after flowering to encourage reblooming in late summer, although the second blooming typically won't be as vigorous as the first. Some gardeners like to prune them back quite hard mid-summer to rejuvenate the entire clump with new foliage.
In regions where perennial cornflowers tend to become naturalized plants, they can be grown with various types of native plants to form a wildflower garden. Because of their drought-resistance, perennial cornflowers are useful in large rock gardens or as edging plants. They are also a good choice for butterfly gardens.
Plant your mountain cornflower in a spot that boasts full sun (for at least six to eight hours a day) in order to guarantee optimal flowering. Locations that have too much shade can cause reduced blooming and make the plant floppy and unsightly.
Mountain cornflower needs well-drained soil in order to thrive, and it can tolerate dry soils quite well—in fact, it does not grow well in especially rich soils. When it comes to the pH balance of its soil, mountain cornflower isn't picky and can tolerate a range of levels, from 6.1 to 7.8.
Once established, mountain cornflower is a drought-tolerant plant, and you should take care not to over-water it. However, young plants will need adequate water (several times a week) to become established, and your watering cadence should increase slightly with especially hot temperatures. When watering the plant, aim your stream of water at the roots so you don't damage the delicate stems.
Temperature and Humidity
Mountain cornflower is, as its name suggests, native to the meadows and woodland areas of central and southern Europe. Given that, it does well in virtually all climate variations through its hardiness range but is an especially vigorous grower in cooler northern climates.
This is one of those plants that seems to dislike rich soil. It needs virtually no feeding—not even soil amendment with organic material. A single spring feeding is occasionally useful for plants growing in hot climates and in very poor soil, but even then it's not totally necessary.
Varieties of Mountain Cornflower
There are several different types of mountain cornflower, most of which can be differentiated by their variety of colors. They include:
- 'Amethyst Dream': A varietal with lacy royal blue petals around a darker purple center.
- 'Amethyst in Snow': A unique spreading varietal that makes a good ground cover and features fringe-like white petals surrounding a purplish center.
- 'Alba': A mountain cornflower version with pure white flower petals surrounding pinkish centers.
- 'Black Sprite': A varietal with star-burst-shaped flowers of dark purple around similarly dark centers.
- 'Carnea': A varietal that features bright pink blossoms.
Propagating Mountain Cornflower
Mountain cornflower will readily self-seed in your garden and any resulting growth can easily be transferred to other locations. More commonly, the entire perennial cornflower clump is divided every two to three years, with the clump pieces transplanted elsewhere.
Common Pests and Diseases
There are few serious insect or disease problems with mountain cornflower, although non-fatal fungal rust or mildew infections sometimes occur. To avoid such issues, make sure you plant the blooms with enough distance in-between them and other plants to aid in air circulation.