Coreopsis ‘Zagreb’ is one of those long-blooming perennials for which gardeners can be grateful. Beginning in June, ‘Zagreb’ produces a starry profusion of clear yellow flowers throughout the summer, as long as it has adequate sunlight and moisture. ‘Zagreb’ is tolerant of light shade, but will not bloom as prolifically in shade as in sun. Contrary to some published information, the plant will re-bloom without shearing—sporadically during July and abundantly during August.
‘Zagreb’ grows 12”-18” high by 18” wide. It has a mounded habit and is, in many ways, a more attractive plant than Coreopsis verticillata ‘Moonbeam’. ‘Moonbeam’ is a taller plant, growing 18”-24”. The flowers are produced only at the very top of the plant, while ‘Zagreb’ creates the appearance of being covered in blooms. ‘Zagreb’ is hardy in Zones 3-9, while ‘Moonbeam’ is hardy in Zones 4-9. ‘Zagreb’ spreads by rhizomes and seeds, whereas ‘Moonbeam’ is a sterile cultivar which only spreads by rhizomes; however, ‘Moonbeam’ can still colonize aggressively.
Coreopsis ‘Zagreb’ is a member of the Asteraceae family, and the verticillata varieties are commonly known as Threadleaf Coreopsis. It is the delicate, needle-like leaves of these coreopsis that are so useful for providing contrast in the garden. Plant ‘Zagreb’ 15”-18” apart in well-drained soil and divide in spring every three years, unless you prefer to let the plant colonize. ‘Zagreb’ is a deer-resistant variety, is unperturbed by winter road salt, and has no observable insect or disease issues.