Threadleaf coreopsis (Coreopsis verticillata), also called tickseed, is a popular summer flowering  perennial. Coreopsis are native to the U.S. and produces hundreds of pale-yellow blooms. Depending on cultivar, plant grows 12 to 18 inches tall and 2 feet wide. Some gardeners even plant old-time favorites like ‘Zagreb’ and ‘Moonbeam’ as annuals (USDA hardiness zones […]