Plant Spotlight: Threadleaf Coreopsis
July 19, 2020
Threadleaf coreopsis (Coreopsis verticillata) is a delicate-looking herbaceous perennial with airy cut leaf foliage, small abundant flowers, and an exceptionally long bloom period. It performs well in urban areas because of its smaller form and tolerance for drought and a variety of soil conditions. Coreopsis is a prolific bloomer that continues through most of the summer garden season and new cultivars for the plant have expanded the color offering to include various shades of white, orange, and yellow mixed with burgundy. Its ferny leaves melt into the background once the plants begin blooming, creating the effect of floating stars in the garden. Waves of color can be achieved by massing the low-maintenance plants in large groupings. Nearly all threadleaf coreopsis varieties have strong heat and drought tolerance.
When, Where, and How to Plant
Threadleaf coreopsis is not finicky and will grow in most any type of soil: clay, loam, sand, or gravel. Most important to its growth is good drainage, consistent moisture, and full sun exposure. Loosen soil to increase drainage by adding compost, gravel, and rotted manure. If planting by seed, do not cover as the seed needs light to germinate. Water regularly until well established.
While coreopsis likes moisture, its rhizomatous roots do not like to be drowned by boggy conditions. In the right cultural conditions, the rhizomes can spread rapidly, so it must be divided or cut-back approximately every 3 years. Threadleaf coreopsis is relatively free of pests, but attracts butterflies and other pollinators.
Coreopsis is a long seasonal bloomer and quite remarkable in rock gardens, dry hillsides, and in drought tolerant beds. Planted en masse in the landscape, the little coreopsis looks like a wave of astounding color. It is an adaptable plant to use as a border or edging perennial in both traditional gardens or along paths. Excellent as a filler planting between larger perennials or potted up in containers and window boxes.
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