Whenever I think of the old-fashioned gardens of grandmothers, aunts or neighbors, I think of cornflowers. I didn't learnlearned to call them by that name until much later in my life. In my youth, they were always bachelor bachelor's buttons.
No matter what name you know them by — cornflowers, bachelor's buttons, bluet, basket flower or the old-fashioned blue-bottle, they are great additions to a flower garden. They are all members of the genus Centaurea, a diverse group of many different species.
The name bachelor's button comes from the lasting quality of the flower when worn in the buttonhole of a suit or shirt. Decades ago, bachelors sported the flower when they went courting. Mountain bluet originates in France. Basket-flower blooms get their name from the ray-like outer petals that make the heads look as if they are set in a shallow basket.
Most Centaureas come from Europe, where they cover fields and waysides and have been part of gardens for centuries. Cornflowers grow wild in corn fields and bloom throughout the season.
The name Centaurea comes from the mythological Greek centaurs, warlike half man-half horse creatures. Chiron, the most peaceful of the centaurs, is said to have used the flower to heal wounds, including his own, after battle and is credited in myth with teaching humans about the healing powers of herbs.
Cornflowers weren't used as medicinals as were other herbs, perhaps in part because of confusion with centaury (Centaurium, now known as Erythraea centaurium), which has a similar name but a different flower color. Both were considered to be beneficial for eye ailments — understandable for cornflowers because of their blue color.
In the mid-1600s, herbalists John Gerard and Nicholas Culpepper included cornflower, or "blew-bottle," in their books on useful herbs. Culpepper claimed the dried leaves could be used as a remedy against the poison of the scorpion if they were mixed in water with plantain or comfrey.
Many different members of this genus grow in our area. Annual bachelor's buttons and basket flowers bloom in late spring and continue through summer. Mountain bluet, from the mountains of Europe, flowers from late spring to early summer. It is hardy to Zone 3 and produces fringed, violet-blue flowers with deep purple centers.
Another Centaurea genus is the well-known bedding plant dusty miller. Centaurea cineraria is grown for its grayish foliage, not its rather unattractive flowers. Although it is perennial, treat it as an annual because it doesn't look very good after winter.
Not all the Centaurea species are welcome. Several knapweeds, as they are known, are serious noxious weeds in our state. Knapweed comes from the rounded, knobby flower knap and is an older English form of "knob." They infest thousands of acres of land in Utah. They are also known as "hurt sickle" because the tough stems of the plants would dull or break a farmer's sickle back the days of hand-reaping.
The non-weedy kinds also do very well here in Utah because they prefer alkaline soil. Finally, a plant that prefers our Utah soil! Most are also drought and heat tolerant, so what more could we want or need in a flower. Don't overwater because if the plants are watered too frequently, the stems get floppy.
Centaureas produce single- and double-fringed blooms on plants from 10 to 30 inches tall, depending on the species or cultivar. The flower petals resemble thistles, but the leaves do not have spines. The leaves are often an attractive gray-green. Tall and double-flowered forms are best for the cutting garden.
Mountain bluet grows two 2 feet tall with an equal spread. The flowers are usually lavender blue but may be rose, pale yellow or white.
Dwarf Centaureas, including the "Florence" series and the "Midget" mixture, get 10-20 inches high. The naturally compact, bushy growth habits are good choices for edging a garden or filling containers. The colors include violet, red, pink, lavender, blue and white.
Centaureas are very easy to grow from seed. Plant them inside for transplants or outside in the garden. They will germinate even when the soil temperature is cool. Sow annual types several times, at two week intervals, to have flowers through summer.
The seeds germinate well when planted about 1/2 inch deep. Keep the seedbed moist until germination. This takes 7 to 10 days for annuals and 2 to 3 weeks for perennials. Thin the annuals 6 to 12 inches apart and perennials 2 to 3 feet apart.
Centaureas look good in informal or wildflower gardens. Interplant them with red poppies and snapdragons or daylilies in borders. Use them in cutting gardens in mixed color plantings or blocks of individual colors. You might even want to recreate some of what Grandma had in her garden by planting them with hollyhocks, goldenrods, Sweet William, love-in-a-mist (Nigella), lavender and other old-fashioned flowers.
Foliage may become ragged and unattractive as the season progresses, so mix them with them with other annuals and perennials in borders or beds where the leaves and flowers will camouflage the base of the Centaureas.
Aphids are usually the only pests that bother cornflowers. Wash the plants with a strong spray of water or use insecticidal soap.
Two fungal diseases, powdery mildew and rust, may cause problems. Space the plants to help prevent powdery mildew. Avoid sprinkling plants that are likely to develop the diseases. Remove infected leaves when you see them. Rust is an infrequent problem that can be controlled by sprays of fungicidal soap, fungicides or sulfur.
Centaureas are excellent for cutting fresh or drying. Fresh blooms last four to five4 to 5 days and dried flowers retain their colors. The petals add bright hues to potpourris, or use the flowers in arrangements.
Make this the "Year of the Centaureas" in your garden. Take advantage of this flower that tolerates our alkaline soil, our hot temperatures and our dry climate and still produces beautiful flowers for gardens, vases, dried flowers or even a decoration for your lapel!