Coreopsis plants are native to the Americas. These plants have herbaceous foliage with daisy-like flowers. A member of the Aster family, coreopsis should be cut back by deadheading in the summer and pruning before the winter and when the perennial plant needs rejuvenation.
Coreopsis blooms throughout summer if spent blooms are removed. The fading blossoms can be snipped off, but often the remaining flower stalk is unsightly. More often the plant is deadheaded by removing the spent flower and its stalk down to plant foliage.
Coreopsis grown as a perennial should be cut back after the summer growing season. Cut back one-third to one-half of the plant's height. Pruning should not extend into the older brown woody growth, as this may kill the plant, according to the University of California Cooperative Extension.
Coreopsis and other profuse flowering perennials decline after a few years. Foliage is sparse and flowers are few in number. These perennials often are rejuvenated by cutting the entire plant off at or near ground level before bloom season. Fertilize and water well to encourage new growth.