Coreopsis are native American prairie and woodland plants. Their ruggedness and profuse blooms have made them popular with plant breeders and there are over 100 different species available, although not all are perennial plants.
Low maintenance, drought tolerant and long blooming, Coreopsis are work horses in a sunny flower border. Their common name, "Tickseed", is supposedly for the seeds resemblance to ticks. That doesn't stop the birds from devouring them, if you leave the seed heads on during the winter.
Most Coreopsis are clump forming, holding their daisy-like flowers on tall stems, above the foliage. There the similarity ends. There is a good amount of variety among Coreopsis species.
Light: Coreopsis will bloom best in full sun, but it can also be successfully grown in partial shade. The plants may get a bit lankier in partial shade, but they will adapt. In areas with intense dry, heat, plants may even prefer some afternoon shade.
Water: They will need regular water when first planted, until they are established.
Temperature: Most of the perennial Coreopsis are hardy in USDA Hardiness Zones: 4-9.
Soil: They are very easy to grow and are not particular about soil quality or soil pH.
Fertilizer: Fertilization of growing Coreopsis is not needed, and too much fertilizer may limit flower production.
Most varieties are very easy to grow and are not particular about soil quality or soil pH. Many can be grown from seed, either started indoors, 4-6 weeks before your last expected frost, or direct seeded outdoors. Many will seed themselves, however the hybrid varieties do not grow true to seed.
Coreopsis will need regular water when first planted, until they are established. After that, they are quite drought tolerant.
Deadheading will keep the plants blooming throughout the summer. Some of the smaller flowered varieties are difficult to deadhead and you may prefer to shear the plants, once the first flush of flowers fade. They will fill in quickly.
Most Coreopsis plants will form tidy clumps, but some of the taller species may require staking to look attractive, especially if grown in partial shade.
Although they are rugged plants, they don't tend to live more than 3 to 5 years. A decrease in flowering is a signal it is time to divide the plants or plant some new ones from seed.
Pests and Diseases
For the most part, Coreopsis grow problem free. In damp seasons they many fall prey to snails and slugs and fungal diseases can affect them. To avoid these problems as much as possible, give them plenty of air circulation and plant them in full sun.