Coreopsis lanceolata, C. verticillata By Dr. William C. Welch, Landscape Horticulturist
Texas A&M University, College Station, Texas
oreopsis are among the most useful native perennials in our area. They are very heat and drought tolerant and require little fussing to produce lavish amounts of color in the garden.
C. lanceolata tends to be rather tall (about 3 feet) and sprawls as it reaches its peak flowering. This is especially obvious after wind or rain and is aggravated by an abundance of water and fertilizer. The foliage is long and slender, and the 2-inch yellow daisy-like flowers appear on long slender stems from mid-spring until really hot weather in July.
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Plains Coreopsis,
an attractive nativeThe good news about Coreopsis is the introduction of cultivars such as 'Baby Sun' and 'Sunray', both of which are more compact and less sprawling in character. 'Sunray' is a semi-double golden orange, and 'Baby Sun' is more yellow. Both stay in the 18-inch height range and have all the good characteristics of the species.
'Gold Fink' is a very compact selection that makes dense tufts of foliage, and can be used as a ground cover in small areas. It is not, however, as well adapted to the Gulf Coast as the other two cultivars, and is often short-lived, melting during the heat of midsummer. Better success can be expected in Central, West, and Northern parts of Texas.
Coreopsis clumps should be divided every 1 to 2 years, and they will usually bloom from seed the first year. Seedlings will appear in large numbers around established plants, but to maintain the dwarf character of the new cultivars, it is necessary to divide existing clumps or purchase fresh seed. Mature clumps will sometimes form plantlets called "proliferation" on the tips of floral stems. These may be removed and quickly rooted in moist potting soil. "Proliferations" will have the same form and size as the parent plant.
As Coreopsis finish their bloom cycle, the seed heads are unsightly. It is best to cut these as close to the foliage as possible to prevent an untidy mass of stubble. Removing spent blossoms and stems often stimulates another cycle of flowering.
The last few years have seen the introduction of C. verticillata into the nursery trade. This is a very finetextured foliage form known sometimes as Threadleaf Coreopsis. At least three cultivars are available. 'Golden Shower' has bright yellow flowers that tend to bloom all summer and into the fall on 2- to 3-foot mounds of airy foliage. 'Zagreb' is the most dwarf form, with a height of about 18 inches and gold flowers. 'Moonbeam' is just slightly larger but with lovely creamy yellow flowers.
C. verticillata cultivars tend to form running thickets of fine stems that may be divided in fall or early spring. All Coreopsis prefer sunny locations and well-drained soil. They like sandy soils and perform well with little or no fertilization.
In addition to use as masses and in border plantings, I have enjoyed C. verticillata, 'Moonbeam', in a large container combined with gray-foliaged Dianthus, which spills over the edge of the pot. C. verticillata and its cultivars are, however, not as well adapted to coastal areas of Texas as C. lanceolata and its kin.