Centaurea

It’s no secret to even casual nature observers that we are having a butterfly free-for-all this year.  Red admirals, those fast flyers with the distinctive orange wing bands, are everywhere.  Experts differ on the reasons for the unusual numbers.  The most common explanation is that the Red Admirals are tourists, lured up from the South by the unseasonable weather north of their usual range. Swarms of them have been reported as far north as Watertown, New York, a place generally known only for enormous snow accumulation. They are also surging in Chicago. Whatever the motivation, the Red Admirals are covering territory like barnstorming politicians.  I find it hard to imagine that butterflies would trade bucolic Virginia for congested New Jersey, but curiosity can do strange things.

I woke up to the butterfly invasion the other day when I was on my knees weeding one of my front beds.  A Red Admiral landed on my shirt and stayed there for about ten seconds.  I hope that I didn’t smell like any of the species’ favorite foods’ tree sap, bird droppings or fermenting fruit – but you never know.  In any event, I looked up and noticed ten more Red Admirals on a small bed of Centaurea montana or perennial cornflower.  I was surprised by the number of butterflies and even more surprised that I had more than ten centaurea.  It seems to me that last year I had only a few.  Clearly the centaurea have been busy while my back was turned.

Centaurea is also sometimes known as mountain bluet.  Native to central Europe, it is a member of the vast Compositae or daisy family.  The flowers, which appear at the top of one foot-tall stalks, look like the result of a mash-up between a daisy and a thistle.  Thistle-like buds open into flowers with frayed, tubular petals in shades of purple, blue and white.  The blues are especially clear and beautiful.  The elongated, medium green Centaurea leaves are nothing to write home about, but they are not ugly. If you have space to fill in a sunny or lightly shaded bed, centaurea will do the job very efficiently, as the plants spread by underground stolons or roots.  My patch started two years ago with a freebie – a little pot of a relatively new cultivar, ‘Amethyst In Snow,’ which has a purple center, surrounded by white petals.  My one ‘Amethyst In Snow’ plant is now ten or twelve plants, which contrast nicely with nearby blue-flowered centaureas. If anything, the bi-colored variety spreads faster than its solid-colored relative.  I don’t mind this, as the centaurea have colonized what was formerly a horticultural dead zone and need almost no care.  If they overrun the confines of their space, I will transplant the extras to other difficult places.

Another benefit to centaurea is that it can be cut back hard after flowering and, with sufficient water, will rebloom later in the summer.  I whack mine off, which they take as a sign of affection.  Both the blue and bi-colored varieties have rebloomed nicely.

My mythology-loving daughter has always been fond of centaurea, because the name conjures up the image of a herd of small centaurs cantering through the garden.  The species name honors Chiron, foremost among the half man/half horse centaurs of Greek mythology.  According to legend, Chiron was skilled in the art of herbal medicine and discovered the medicinal use of centaurea. The plant has traditionally been used for conditions including conjunctivitis. The species name, “montana,” commemorates its mountainous native habitat.

There are a number of cultivars in commerce.  One of the most common is the striking ‘Gold Bullion,’ with black-centered blue flowers and golden green leaves.  This is especially good for lighting up slightly shaded areas.  The Dutch-bred ‘Amethyst Dream’ has large, purple blooms that also make excellent cut flowers.  Those with fashionable black and white garden color schemes will appreciate ‘Black Sprite,’ a compact variety with gray foliage and black petals.

For gardeners like me, who tend to be lazy or neglectful, centaurea is the perfect plant.  It is unfussy as to soil conditions and once established, is relatively drought tolerant.  Some sophisticated gardeners overlook them, probably because of their galloping habit.  However, once you have seen the vivid blue of a traditional centaurea, you will want it in your garden.  I aim to acquire more varieties.  There are those who covet flocks of pink flamingos in the garden.  I am more partial to herds of colorful centaurs.

Many large garden centers carry centaurea and ‘Amethyst In Snow’ seems especially prevalent commercially.  If you can’t find the plants at a nearby merchandiser, order them from Bluestone Perennials, 7211 Middle Ridge Road, Madison, OH, 44057, (800) 852-5243; www.bluestoneperennials.com.  Catalog free.