Threadleaf coreopsis, or coreopsis verticillata, is a hardy perennial that grows in United States Department of Agriculture zones three through nine. It is easy to grow, and makes a wonderful addition to group plantings, containers, and mixed beds. The plant is a native wildflower in many areas of the United States. Threadleaf coreopsis has small yellow flowers that resemble daisies. The plant's foliage is delicate and feathery, making it a wonderful addition to cut flower arrangements.
The threadleaf coreopsis is also known as tickseed and tickweed. It requires little maintenance once it is established, and returns year after year with long lasting blooms. While not picky, threadleaf coreopsis prefers well-drained soil. It does not require supplemental fertilization in average gardening soil, and can thrive in less than ideal conditions. The plant prefers full sun, but can tolerate partial sun and light shade.
The plant flowers in June and continues to produce flowers until frost. To keep the plants full of flowers, deadhead spent blooms. Leaving the blooms on the stem to fade signals the plant to stop producing flowers. Pinch the blooms off as soon as they begin to fade, and the plant will continue to produce blankets of yellow flowers throughout the season. When mature, the plant reaches a height of 16 to 24 inches(40 to 61 cm), and is between 15 and 18 inches(38 to 46 cm) wide.
The prolific growth of the threadleaf coreopsis means that it is easy to start new plants from existing ones. Every three to five years, dig up the plant and use a spade to slice the root ball in half. Replant each half as separate plants.
The threadleaf coreopsis attracts many types of wildflowers to the garden, including birds, bees, and butterflies. They do not attract many pests or disease. In some cases, slugs or snails may attack the plant. During wet periods, or if the plant is over-watered, it may develop fungus.
Threadleaf coreopsis is one of many plants that originated as wildflowers and have become common in flower gardens. Other flowers that grow wild as well as in the garden include woodland phlox, great blue lobelia, lupine, and Virginia bluebells. Combining these flowers creates a natural-looking wildflower garden. Wildflowers are typically less particular about soil type and sun amounts than other types of flowers, and these flowers are no exception. Wildflowers attract hummingbirds, butterflies, and other wildlife to the garden.