Heuchera x brizoides 'Leuchtkafer' 'Leuchtkafer' Hybrid Coral Bells Size: 18 to 30" high by 1' spread. Hardiness: Zones 3 to 9. Heat Zones: 8 to 1. Habit: Low, dense mounds of rounded or heart-shaped evergreen leaves are topped with wiry, branched stems covered on the upper reaches with beautiful bell-shaped flowers. Culture: Full Sun to light shade.