Keep weeds under control during the coreopsis growing season.Weeds compete with plants for water, space and nutrients, so control them by either cultivating often or use a mulch to prevent their germination.
Mulches also help retain soil moisture and maintain even soil temperatures. For perennials, an organic mulch of aged bark or shredded leaves lends a natural look to the bed and will improve the soil as it breaks down in time. Always keep mulches off a plant’s stems to prevent possible rot.
Careful watering is essential in getting perennials off to a good start. Water thoroughly at least once a week to help new roots grow down deeply. Soil should be damp at about 1 inch below the soil surface. You can check this by sticking your finger in the soil. Water early in the morning to give all leaves enough time to dry. One inch of rain or watering per week is recommended for most perennial plants. You can check to see if you need to add water by using a rain gauge.
Until plants become established, some protection from extreme winds and direct, hot sunlight may be necessary. Good air movement is also important.
After new growth appears, a light fertilizer may be applied. Keep granular fertilizers away from the plant crown and foliage to avoid burn injury. Use low rates of a slow release fertilizer, as higher rates may encourage root rots.
Coreopsis appreciates a protective winter mulch after the ground freezes north of zone 6.
Divide the plants in spring or fall for propagation or to rejuvenate old clumps.
Coreopsis Growing Tips
Many gardeners do not cut back perennial flower seed heads in the fall, but wait until early spring before the new foliage appears. This provides food for wildlife over the winter.
Coreopsis is valuable for the middle or front of the border and is an ideal addition to dry-soil gardens.
The cut flowers are long-lasting and a welcome addition to fresh arrangements.