Sustainable and xeric gardens benefit from the addition of the Stokes aster (Stokesia laevis). Care of this charming plant is minimal once the Stokes aster plant is established in the garden. You can grow Stokes asters for a burst of spring and summer color against a backdrop of evergreen shrubs and native foliage plants for a pleasing display.
I. Appearance and Characteristics
Stokesia is a monotypic genus of flowering plants in the daisy family, Asteraceae, containing the single species Stokesia laevis. Common names include Stokes’ aster and stokesia. The species is native to the southeastern United States.
The flowers appear in the summer and are purple, blue, or white in nature. The plant is cultivated as a garden flower. Several cultivars are available, including the cornflower blue ‘Klaus Jelitto’, ‘Colorwheel’, which is white, turning purple over time, and ‘Blue Danube’, which has a blue flower head with a white center. More unusual cultivars include the pink-flowered ‘Rosea’ and yellow-flowered ‘Mary Gregory’.
Like a few other plants (such as some species of Vernonia), it contains vernolic acid, a vegetable oil with commercial applications.
The genus is named after Jonathan Stokes (1755–1831), English botanist and physician.
II. How to Grow and Care
Sunlight
Choose a planting site that receives at least 6 hours of bright sunlight a day for best blossoms. While the plant can tolerate partial shade, it will not bloom as vigorously.
Temperature and Humidity
As a native of the southeastern United States, this perennial can handle the heat and humidity of a hot summer.
Stokes’ aster is hardy in winter down to zone 5 but at the lower end of its range, cut stems back to basal foliage and cover plants with a thick layer of mulch in late fall. Don’t water the plant during dormancy; wet soil in the winter is the leading cause of death for Stokes’ aster.
Watering
Once Stokes’ aster is established, it is considered to be drought tolerant but until then, new plantings will need to be well watered, particularly through the flowering season. If the soil is allowed to remain too wet, this can kill off the plant in the winter so make sure to only water once the soil is dry on the surface.
Soil
Stokes’ aster prefers a moist soil with good drainage. It’s not overly fussy about soil pH. After it establishes a strong root system, it is tolerant of both heat and dry conditions. It also manages well in occasionally wet soil.
Fertilizing
Stokes’ aster will benefit from a slow-release general purpose fertilizer applied in the spring to boost the plant through the growing season. For stokes’ aster that grow in pots, you can fertilize twice per month when flowering to prolong the blooms.
Planting Instructions
Plant Stokes’ aster in the spring after the last average frost date in your region. To transplant a seedling or nursery specimen, dig a hole about the same width and depth as the planting container. Remove the plant and loosen the roots a bit from the root ball before placing in the hole. Backfill with soil, tamp lightly, and water well.
Space multiple plants 20-24 inches apart.
Pruning
Remove spent flowers as soon as they droop to promote reblooming. Shear plants in midsummer, if needed, to create dense new growth.
Propagation
Plants can be divided every two or three years in early spring. To divide, dig up the plant and cut or break the clump into smaller sections with leaves and roots attached. Plant these into the garden at the same depth as the original plant and water well.
You can also increase your supply of Stokes’ aster via cuttings. In spring, take 4-inch cuttings from the plant’s stem tips. Remove the leaves from the bottom half of each cutting and dip it in rooting hormone. Put each cutting into a small pot filled with loose potting soil. Cover each pot with a clear plastic bag with air holes punched in it. Put the pots in a bright area (not in full sun) and keep the soil moist until the plants root. When you see any new growth, remove the plastic bag.
To grow Stokes’ aster from seed, fill a tray with moist seed-starting mix about 6-8 weeks before your average final frost date. Cover with a thin layer of soil or vermiculite (about 1/8 inch is sufficient) and place in a warm spot or on a heat mat. At 70 degrees F, the seeds will germinate in 2-3 weeks and continue to sprout up to 5 weeks or so. Keep the soil evenly moist during germination and as the seedlings grow. When all danger of frost has passed, you can harden off your seedlings and plant them in the garden.
Potting and Repotting
Select a container with large drainage holes that fits the root ball plus at least 2 inches to accommodate future growth. Fill it with a combination of well-draining potting mix and compost. Keep in mind that potted plants, unlike plants in the landscape, require more frequent watering and fertilization.
Once the roots of Stokes’ aster fill the pot, or grow out of the drainage holes, repot it in a large pot with a fresh potting mix/compost combination.
Pests and Diseases
Stokes’ Aster has no serious insect or disease problems. Rabbits often devour Stokes’ aster. If planted in an area with a large rabbit population, be sure to provide protection by installing a chicken wire fence.
Flower stems do tend to flop when wet, particularly after a heavy rainstorm.
III. Types of Stokes’ Aster
- ‘Blue Danube’
Fluffy, sky-blue cornflowerlike blooms grow to 18 inches tall and wide. The flowers make a lovely addition to summer bouquets. Zones 5-8
- ‘Alba’
This cultivar features snow-white flowers on multi-branched stems and blooms from June to September. Zones 5-9
- ‘Peachie’s Pick’
The lavender-blue flowers of ‘Peachie’s Pick’ are butterfly magnets and bloom from midsummer to early fall. Zones 5-9.
IV. Stokes’ Aster Companion Plants
- Globe Thistle
Globe thistle (Echinops ritro) is a joy to grow. This sun-loving perennial produces showy bright blue or white thistlelike spherical blooms from mid to late summer. The flowers also look beautiful in fresh or dried arrangements. Globe thistle is heat- and drought-resistant but doesn’t transplant well, so plant globe thistle where you want it to grow permanently. The plants may self-sow if you allow the blooms to mature on the plant. Zones 3-8
- Anise Hyssop
This tough, drought-tolerant perennial looks beautiful for months in summer and fall. That’s when anise hyssop is covered with spikes of lavender-blue, licorice-scented flowers that pollinators love. It’s also known as hummingbird mint because this mint family relative draws plenty of these winged visitors. Zones 4-9
- Stonecrop
The fleshy leaves and spectacular flowers make tall sedum (also called stonecrop) a popular perennial. It’s practically foolproof as long as the soil doesn’t stay overly moist. It blooms toward the end of summer into fall when most other flowers are fading. Plus, the dried flower stems add winter interest if you leave them in place. Zones 3-10
- Russian Sage
A tall, elegant summer bloomer, Russian sage bursts forth with feathery wands of violet-purple flowers over masses of silvery foliage. Like many other plants disliked by deer, it bears scented foliage. Zones 4-9
V. Uses and Benefits
Notable for its evergreen foliage and blue to violet, fluffy, fringed flowers that bloom from midsummer to the first frosts, stokes’ aster looks best when planted in groups or masses. It is ideal for bringing some lilac-colored freshness to border fronts, in cottage gardens, and alongside ponds and streams. It is also highly attractive to insect pollinators.
