Coreopsis: Tickseed or Pot of Gold?

By Penye Cushing
U.C.C.E. Master Gardener

With a nickname like Pot of Gold, don’t you want some? Their bright shiny faces bloom from spring through summer–long after most perennials have faded from the garden. They acquired their common name, Tickseed, because someone thought the seeds looked like little ticks…absolutely nothing to do with the nasty pests! These plants are a great treat for our natural pollinators’ pleasure.

Asteraceae calliopsis is a genus of 33 species of flowering plants native to the U.S., and belongs to the sunflower family. 

Coreopsis is clump forming, holding their daisy-like flowers on tall stems above the foliage. From this point there is a good amount of variety among the Coreopsis species. They are mostly known for a sunny yellow color, but it can also be found in red, pink, and white, most with a maroon or brown center, which creates great color and contrast.

There are over 100 different varieties. Not all are perennial, but all are low maintenance, drought-tolerant and long blooming. Sounds too good to be true! But this is a great plant. Though many of the newer varieties are still being tested for hardiness, and the temp rating may change, most are hardy in USDA zones 4-9.

Plant size will vary with species, age and your growing conditions, but most plants grow between 10-18” tall, and spread to approx. 12-24.”  Coreopsis are prolific self sowers. A few will spread by runners, which makes it easy to move to a new beauty spot in your garden. A reliable border plant, they are also great as fillers in areas of resting natives.

Coreopsis prefer full sun, but can be grown here successfully in partial shade. Consider that they may get a bit leggy in partial shade. They are very adaptable, but in areas of dry heat, coreopsis might appreciate a little afternoon shade. 

To get coreopsis started from seed in the spring, prepare an area of un-amended soil in a full sun location. The seeds need light to germinate, so cover lightly with soil or perlite or simply gently press seeds into moist soil.  Keep seeds watered until germination, usually within 21 days. You might have to mist the seeds to keep moist. 

Coreopsis seeds can be started indoors 4-6 weeks before your last expected frost. Here in our area that safety date is March 1st (old-school farmer date).  Many will self-seed; however, the hybrid varieties do not grow true to the seed. Coreopsis may also be started from cuttings from spring to mid-summer. If you have a buddy with some, perhaps you can add to your garden’s variety!  

They need regular water when first planted until they are established. After that, they are quite drought-tolerant. 

Most start blooming in early summer and repeat bloom through fall. Deadheading the spent flowers will encourage more blooms, although birds adore the seeds, so you might want to leave the spent flowers on during the winter. After their first bloom in midsummer, shear back to approximately one-third of original plant size to encourage more blooms.  Please do not fertilize as this may limit flower production.

You can find several varieties in plant stores.  The best selection will be found in catalogs or start your own plants from seed. 

Coreopsis grandiflora has a strong tendency to self-seed and makes a great choice for cottage style gardens. They pair well with coneflowers and gaillardia. This variety makes good cut flowers.

Coreopsis rosea has extremely fine, ferny leaves.  The pink flowers with yellow centers are delicate and profuse. This thread-leaf variety looks wonderful against bold leaves or hard edges. Plus, they add an airy movement to the garden. 

Coreopsis auriculata ‘Nana’ is a mauve-pink dwarf spreading to 8”.  They are short-lived, but their color blends beautifully with the purples and blues of iris, liatris and Salvia ‘Victoria.’

Coreopsis vertilcillata ‘Moonbeam’ is buttery yellow and extremely airy at 12-18”

Though most will form tidy clumps, some of the taller species may require staking to look attractive, especially if grown in partial shade. These rugged little wonders do not seem to live more than 3-5 years. You can tell their aging process by diminishing flowers. This is your clue to divide the clump or plant some new babies.  

For the most part, coreopsis grow problem free. In damp seasons they may be a delicacy for snails and slugs. To assist health, give the plants plenty of air circulation and full sun.  

But if you should develop an issue one of the following will probably be the culprit. 

  • Rhizoctonia, Verticilium wilt, and Botrytis blight are all fungal diseases that cause the plant wilt and die. Remove infected plant to prevent diseases from spreading.
  • Downy mildew and Powdery mildew can be treated with a fungicide. Powdery mildew will not kill your plant, but it is not attractive. Downy mildew can cause black spots on the leaf’s upper surface, while the undersides have the traditional white fuzz.
  • Fungal Leaf Spot causes tan to purple leaf spots and can also be treated with a fungicide.
  • Rust and scab show as a mass of spores on plant leaves. Rust leaves orange spores on the underside of leaves, while scab shows as a coating of gray to brown spores.
  • Aster Yellow is a phytoplasma disease carried by leafhoppers. This disease turns plants yellow and failure to grow properly, while the flower heads appear in greater number than usual. The petals are deformed or greenis. Slow the spread of the disease by removing any infected flowers as soon as you see them and keep area free of weeds. 

Since many of these diseases are from overhead sprinkler watering, it is best to water from below on your drip line to keep plant from staying wet for an extended time.  

Coreopsis provide three-season shows of color with very little work on your part. Your neighbors will envy your curb appeal!  Enjoy this reliable flower for its long- lasting beauty and ease of care in your Central Valley garden.

The UCCE Master Gardeners will be available to answer your gardening questions at the Farmers Market in the Visalia Sears parking lot on Saturdays from 8 a.m. to noon, or at these upcoming venues:

Sat., April 21 – Earth Day Visalia Info Booth, Imagine U Children’s Museum, 210 N. Tipton St., from 9:30 a.m. to 2:30 p.m.

Sat., April 21 – Exeter Garden Club, Exeter Memorial Building from 11:30 a.m. to 1 p.m.

Sat., May 5 – Spring Into Gardening Festival, Hurley School, Visalia, from 10 a.m. to 2 p.m.

To contact the Tulare/Kings Master Gardeners, call 559-684-3325, e-mail [email protected] or write to 4437 S. Laspina St., Ste. B, Tulare, CA 93247.

This column is not a news article but the opinion of the writer and does not reflect the views of The Foothills Sun-Gazette newspaper.

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