the coreopsis are 20-30 species of perennial or annual herbaceous plants, originating in North America. These plants appear as dense tufts of dark green leaves, from which long stems depart in spring on which large yellow or orange flowers bloom. The Coreoxyde tinctoria is perennial and has yellow flowers with a brown center; C. verticillata is perennial and forms dense bushes 100-150 cm high, with golden yellow flowers; C. grandiflora is a perennial with a very short life, 2-3 years, with simple or double yellow flowers. Even the coreopsis perennials tend to dry out completely in winter, and then reappear in early spring. The most common and known variety is certainly the grandiflora, which is successfully cultivated, although it is short-lived, thanks to the easy cultivation and the fact that it does not require particular cultivation techniques to obtain good results.
The plants of this particular arboreal species prefer very sunny locations, but they develop well even in partial shade, in a place where they can receive a few hours of direct sunlight a day; the locations that are not very bright and in shaded areas cause, in fact, a poor production of flowers, a fundamental characteristic for having a colored garden. They do not fear the winter cold, also because the perennial species in cold periods go into complete rest, awakening then at the time of vegetative growth without presenting particular problems.
Coreosside specimens need regular but not excessive watering, it is advisable to check that water does not build up and avoid soaking the substrate too much, letting it dry slightly between one watering and another.
These plants are very hardy and therefore endure without occasional drought problems or with excessively damp soil, although prolonged stagnation of water can cause damage and radical rot.
It is advisable to add fertilizer for flowering plants to the watering water every 15-20 days in the period from March to September to allow the plant to grow vigorously and compactly and to provide an intense and lasting flowering.
The Coreosside specimens prefer to be planted in loose, well-drained and fertile soils, but this variety has a high rusticity and excellent resistance, it can grow without particular problems in all soils, even those that are mainly chalky or clayey. Thanks to its adaptability, in fact, this plant is indicated even when the soil conditions are not optimal.
The reproduction of this genus of perennials takes place by seed. To obtain good results, it is preferable to sow the coreopsis, both perennials and annuals, directly in the spring. The plants of C. verticillata can also be propagated by dividing the old tufts, in spring, and placing the new plants directly on the ground.
Coreosside - Coreopsis: Pests and diseases
These plants are very resistant and hardly attacked by pests and diseases. This fact allows to avoid to intervene periodically with insecticidal treatments with specific products, given that the specimens this genus turn out to be particularly resistant and rustic.