Saturday, August 1, 2009

Brighten Your Garden With Coreopsis

One of the first perennials I favored has stuck with me all these years, and that is Coreopsis, commonly called Tickseed. Coreopsis is a bright-flowered plant with blossoms shaped like large asters. It is, in fact, part of the Aster family. Color is mostly yellow, but there are some in pink shades, too.

Tickseed comes by its name truly. Coreopsis means "bug-like", in reference to the little dry fruits called achenes which in some ways resemble insects. Not only are the seeds small and brown, they have hair-like structures that cause them to stick to passers-by who brush against them; and they don't just drop off, they must be picked off. Thus the name, Tickseed.

Coreopsis (pronounced "co-ree-AWP-sis") is native to the U.S., and, thankfully, its ornamental value is widely appreciated. Three species are commercially propagated and researched for new cultivars.

C. auriculata is commonly called Mouse-ear Tickseed. Auriculata (pronounced "awe-rick-ewe-LAY-tah") means "ear-like" or "lobed." It thrives in USDA climate zones 5 through 9. Maximum height is 6" to 12". C. auriculata 'Nana' is the shorter. ("Nana" means "dwarf.") It prefers slightly moist, well-drained garden soil with pH ranging from slightly acid to slighty alkaline. It will tolerate short periods of drought. Mature plants grow to 10" across. It will produce a beautiful carpet in optimal conditions. Plant in full sun. Space at 8" to 12". It is semi-evergreen, meaning that some foliage just above soil level will remain during cold weather.

C. auriculata is suited for butterfly gardens, sunny perennial gardens and borders when planted with species having similar requirements. The dwarf, 'Nana', is a fine, low maintenance ground cover.

C. grandiflora is commonly called Big-flowered Tickseed. It thrives in USDA climate zones 4 through 9. Maximum height is about 18". Plant in full sun and slightly moist, well-drained soil with pH widely ranging from 5.1 to 8.5. Space 18" to 24" apart. Soil should not be allowed to become bone-dry between waterings. C. grandiflora is deciduous, though some foliage may remain at lower levels in warm climates. Bare stems should be cut short in winter.

C. verticillata (pronounced "ver-tiss-ill-A-tah") is commonly called Thread-leaf Tickseed. It also thrives in USDA climate zones 4 through 9. Maximum height is 18" to 24". Plant in full sun to partial shade in moist, well-drained soil ranging from slightly acid to slightly alkaline. Space at 18" to 24" apart. C. verticillata should be cut short in winter.

Both C. grandiflora and C. verticillata are good for butterfly gardens, perennial gardens and borders, and container gardens.

Prepare the planting bed for Coreopsis by cultivating at least 6" deep, removing all traces of weeds. Compacted soil should be cultivated to 10" deep. Composted manure may be incorporated into the soil. Fertilizer may be used. If you choose to do so, incorporate 5-10-15 fertilizer at a rate of no more 2 lbs. per 100 square feet into the top 4" to 6" of soil. Avoid synthetic fertilizers contacting any part of your plants.

Container-grown Coreopsis can be planted any time you have a shovel handy, but will require monitoring of soil moisture conditions during hot weather to avoid plant stress.

Space plants 12" to 24" apart, as indicated earlier. Keep in mind that my spacing recommendations are approximate. If you want them to fill in quickly, plant closer together. If you have plenty of time and patience but less money, plant them farther apart. Dig planting holes into the cultivated soil a little less deep than the depth of the growing container. Place the plants into the holes and back-fill. Press soil around the roots. Do not cover the root balls with soil. The tops should be slightly exposed. Add a top-dressing of mulch around the plants, not on top of them, about 2" to 4" deep. Irrigate thoroughly.

Maintenance is minimal. Dead-heading (pinching off spent flowers) can prolong the bloom season. Coreopsis have few pest and disease problems, but they aren't immune. Spider mites can cause problems during dry weather, but the little critters hate water. So overhead irrigation discourages them. If you are keeping the soil slightly moist, as you ought, spider mights shouldn't be a problem. Deer can do damage.

For a sunny summer plant that will brighten your garden and spirits, I highly recommend Coreopsis.

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