Cultivating plants native to North America has become a widespread garden trend. Coreopsis (also known as tickseed), with 100 or so species, is among the foremost in the vast range of plants that have grown wild on prairies and in woodlands on this continent for centuries. With its abundant and colorful daisy-shape flowers, tickseed is popular for home gardens as well as public ones.
Some Coreopsis species are annuals (such as C. tinctoria, also called plains calliopsis, or C. californica), but more species are perennial, albeit short-lived in some cases (such as pink tickseed, C. rosea). Research has shown that plants with fleshy underground stems or rhizomes (such as C. verticillata) are more likely to be reliably perennial than those that have clumping rootstocks (C. grandiflora). Green lance-shape, oval, or threadlike leaves are usually opposite; they seldom display fall color. Small flowers crowd into a flower head, also called a capitulum. These flower heads are composed of ray florets (often called petals) that surround the central disc florets, a characteristic of the daisy or aster family (Asteraceae). The unfortunate common name, tickseed, refers to the plant’s tiny, dry, flattened, buglike seeds.
Coreopsis has benefited from the attention of plant breeders, especially in recent years. Historically, gardeners viewed tickseed only as short-blooming perennials, overlooking them as garden plants in favor of more robust genera. Modern breeding, led by long-blooming, pale yellow C. ‘Moonbeam’, has produced a wide assortment of colorful and reliably long-blooming hybrids, often from late spring, reblooming into early fall. Several perennial species, including big-flowered coreopsis (C. grandiflora), lance coreopsis (C. lanceolata), pink tickseed (C. rosea), and threadleaf coreopsis (C. verticillata), were included in hybridization programs to produce a fine range of perennial cultivars and selections. Blossoms are now available in bright, brassy, and butter yellows, in pinks and reds, monochrome and bicolor, double and single, as well as on plants of differing heights (from 6 inches to 4 feet or more tall) with both mounding and upright habits.
GROWING TICKSEED: Generally both annual and perennial coreopsis species are easy to grow, except in hot and humid climates. Under those conditions the plants tend to open up and sprawl, as well as become more susceptible to mildew, both downy and powdery. Full-sun locations with sandy soil are best; even poor rocky soils are adequate. Most tolerate drought and dry conditions (C. rosea is an exception). If drainage is poor, pile the soil to create a mounded bed that speeds rain runoff. They benefit from routine deadheading. It is wise to divide robust plants every two to three years to maintain vigor. Deer and rabbits seldom browse tickseeds.
POLLINATORS: Although not favorites of pollinators, coreopsis flowers have an extended bloom time. Pollen and nectar are harvested from the flower heads by several species of sweat bees, bumblebees, honeybees, and hoverflies. Wasps, butterflies, beetles, and moths are frequent visitors.
PROPAGATION: Many species—particularly lance coreopsis, big-flowered coreopsis, and mouse-ear coreopsis (C. auriculata)—are readily started from seed, but vegetative division or cuttings are required to increase the hybrids (‘Moonbeam’, ‘Redshift’, and ‘Star Cluster’, for example). Nurseries and garden centers carry a selection in spring.
WHERE TO GROW: Few sunny places in residential gardens are unsuitable for tickseeds. Try bright yellow ‘Zagreb’ (20 inches) or peach ‘Sienna Sunset’ (10 inches) in rock gardens, as edging plants along beds and pathways, or perhaps in front of foundation plantings. Low-mounding selections, including the colorful Big Bang series, suit containers well. Wherever you choose to plant tickseeds, they will reward you with an abundance of flowers over several months. Check with your local nursery or Cooperative Extension office for those that perform best in your climate. The following are hardy in Zones 4–9 unless otherwise noted.
FOR EDGING FLOWERBEDS:
• C. auriculata ‘Nana’ is mostly free of mildew. Yellow flowers attract butterflies. 6–9 inches tall. Similar ‘Zamphir’ has heads of orange-yellow flowers on 12–18-inch plants.
• C. Solanna 'Golden Sphere' produces double, bright yellow flowers above mounded plants with dark foliage. Good for cutting. 12–18 inches. Zones 5–9.
• C. ‘Mercury Rising’, from the Big Bang series, has large claret daisies centered with yellow. Does not care for hot summer climates. 12–18 inches. Zones 5–9.
FOR COTTAGE GARDENS:
• C. verticillata ‘Zagreb’ has 1- to 2-inch bright yellow flower heads with a darker center. 12–18 inches tall. Zones 3–9. ‘Golden Gain’ is similar but not quite as hardy.
• C. ‘Tequila Sunrise’. Yellow daisies with a maroon eye; foliage is variegated yellow and green. 12–18inches. Zones 5–9.
FOR THE BACK OF BORDERS:
• C. tripteris has yellow-ray, brown disk flower heads. Tolerates heat, humidity, and drought. Self-seeds freely. 2–8 feet tall. Zones 3–8.
• C. tinctoria, plains coreopsis is annual but self-seeds freely. Bicolor, red-eye yellow daisies, often 2 inches across. 4 feet tall. Long-blooming and good for cutting. Zones 2–11.
• C. ‘Sienna Sunset’ is a sport from ‘Crème Brulee’ with brownish-orange flowers. Threadleaf foliage. 12–18 inches. Zones 5–9.
• C. ‘Heaven’s Gate’ is darker than C. rosea ‘Sweet Dreams,’ with pink flowers and a purple center. 9–15 inches. Zones 5–8.
• C. ‘Limerock Ruby’ has beautiful crimson ½-inch daisies with yellow centers held above 8- to 12-inch mounds of foliage. Zones 8–9.
PLANT AT A GLANCE: COREOPSIS
COMMON NAME: Tickseed
BOTANICAL NAME: Coreopsis species, cultivars, and hybrids
HARDINESS: Zones 3–9
CONDITIONS: Coreopsis are mostly sun-lovers, although some species tolerate part shade. Provide them with well-drained, fertile soil.
BLOOM TIME: Bloom begins in late spring and early to midsummer and may continue well into late summer. Many have daisy flowers borne on long stems that are appropriate as cut flowers.
HEIGHT: 10 inches to 4 feet tall or more
BEST FEATURE: The long bloom time and daisy like flowers of coreopsis are their best features. The plants are also prized for their toughness and ease of culture. The flowers attract pollinators including butterflies, bees, and other insects searching for nectar and pollen. While attractive and valuable as ornamental plants in beds and borders, some coreopsis species are appropriate for meadows, native plant gardens, and prairie restorations.
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