Coreopsis verticillata Threadleaf coreopsis Size: 18 to 36" high by 12 to 36" wide. Hardiness: Zones 3 to 9. Heat Zones: 9 to 4. Habit: Produces open clumps of upright stems with very narrow leaves divided into almost needle-like segments, giving the plant a lacy, see-through appearance. Culture: Full Sun to light shade.