1200 CORAL BELLS (Prairie Alumroot) Heuchera Richardsonii Flower Seeds BLOOM TIME: Spring HARDINESS ZONE: 3 - 9 PLANT HEIGHT: 24 - 36" . . . PLANT SPACING: 15 - 18" LIGHT REQUIREMENTS: Sun - Part Shade . . . SOIL / WATER: Average Coral Bells are prized for their neatly mounded foliage.