Black Flowers That Bring Bold Drama to the Garden Black Velvet Petunia annual, deep velvety blooms Black Dahlia bold summer blooms, Zones 811 Black Iris striking petals, Zones 49 Black Calla Lily elegant curves, Zones 810 Black Magic Hollyhock tall spires, Zones 39 Black Hellebore winter blooms, Zones 49 Black Tulip spring classic, Zones 38 Black Star Gladiolus tall and dark, Zones 710 Black Rose hybrid varieties, Zones 59 Black Viola small, near-black petals, Zones 39 Tip: Deep colors show best in full sun and rich soil.