Stokes’ asters have always been among my favorite native perennials though I have typically only grown them in small drifts of five to seven plants. Now at the Columbus Botanical Garden I’ve got more than a hundred. They are an absolute knockout, and the American lady butterflies are finding them to be a real feast. Striking blue flowers and fiery orange butterflies is a combination that is hard to beat in any garden.
The Stokes’ aster is known botanically as Stokesia laevis and is native in the south from Louisiana eastward to North Carolina. Despite this southern flavor, they are cold-hardy to zones 5 and 6 with a good layer of mulch. This means almost everyone can enjoy their exquisite blooms.
The blooms are large, reaching 3 to 4 inches wide and almost as exotic looking as those of the passionflower. The blooms are heaviest in early summer but the plants keep some producing for a long period. In our garden we have the typical sky blue, some deep dark blue and others that are a pristine white.
Though native, you will find several great choices in named selections. The violet-colored Purple Parasols has performed wonderfully for me. Other varieties you may want to try are Blue Danube (lavender blue), Bluestone (blue), Klaus Jelitto (light blue) and Wyoming (purple). But should generic be the only thing available, don’t fret, they are still great plants for the landscape.
For the best show plant them boldly in informal drifts. You can combine them in perennial gardens with coreopsis and rudbeckia for a wonderfully complementary color scheme. But I have also seen that some incredible partnerships can be made with SunPatiens.
The shocking orange available in SunPatiens makes for a riotous, eye-catching companion with deep blue varieties. Of course the pink SunPatiens would partner with all colors of Stokes’ asters. I have also grown Purple Parasols with Stella d Oro daylily which makes a very nice companion planting both from a color and a perennial standpoint.
Choose a site in full sun for best blooms, but partial shade is tolerated much better than many other perennials. Make your beds well-drained by incorporating 3 to 4 inches of organic matter -- like fine pine bark, humus or compost. Well-drained acidic soil is pretty much mandatory. Wet winter feet can spell doom.
Till your bed to a depth of 8 to 10 inches and add 2 pounds of a slow-release, 12-6-6 fertilizer into the bed. Plant 6-inch, to gallon-sized plants now and set out at the same depth they are growing in the container. The plants reach 18 inches in height. You will want to space them 15 to 18 inches apart.
Our Stokes’ asters had spread much more than desirable and even to the point that previous year’s blooms had been sparse. We did a heavy thinning with the emergence of spring growth and now the blooms are amazing. You will notice your clumps too will become large when this happens just make sure you divide, it will be easy. When the stalks have finished blooming promptly cut them back to the base, even with the plant. This will prolong you bloom production.
You may also want to use them as cut flowers. You’ll be pleasantly surprised how long they last in the vase. The color blue is much sought after in the garden. Partner this with exotic-looking blooms that attract butterflies and you’ve got a real winner.
(Norman Winter is executive director of the Columbus Botanical Garden, Columbus, Ga., and author of “Tough-as-Nails Flowers for the South” and “Captivating Combinations Color and Style in the Garden.”)
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