Native to South Africa, lily-of-the-Nile (Agapanthus spp.) plants become fountain-like clumps of deep green, strap-like leaves that often persist year-round. In late spring to midsummer, tall stems rise up, each carrying a cluster of flowers called an umbel. Generally, the flowers are bell-shaped, often drooping, and are in shades of blue. Describing and grouping plants that bear blue flowers is difficult, as differentiating color shades like "sky blue," "blue-violet" and "clear blue" is subjective. Always purchase plants when in bloom to guarantee a shade of blue that you most like rather than relying solely on adjectives on labels.
Hybrid cultivars named "Tinkerbell" and "Streamline" bear flowers that range from pale blue to grayish blue. The species Agapanthus campanulatus subsp. patens produces umbels with larger numbers of tiny flowers than others that are light blue, including the variegated leaf selection named "Albovittatus."
Medium or Clear Blue
Perhaps this generalized color range encompasses the standard of colors seen in the wide array of lily-of-the-Nile species and cultivars available to gardeners today. Minute hints of cobalt, cerulean or sky-blue hues can muddy the ambiguous medium-blue description. Examples include species Agapanthus praecox (Agapanthus orientalis) and hybrid cultivars like "Blue Giant," "Flore Pleno," "Blue Triumphator" and "Peter Pan." Within the species Agapanthus campanulatus are individual plants with varying flower shades in the medium-blue range, too.
Deep or Dark Blue
Here are deeper blue colored flowering types, including those that are blue-violet. Three species typically produce these deep blue flower colors: Agapanthus africanus, Agapanthus caulescens and Agapanthus inapertus. Some seedling plants of Agapanthus campanulatus will display dark blue flowers. Hybrid selections with deep blue to blue-violet flower petals include "Lilliput," "Isis," "Elaine," "Ellamae" and "Midknight Blue."
Violet to Purple
Arguably, some may think the deep blue flowers of Agapanthus inapertus are more appropriately considered more purple than blue; the comment has merit. Other hybrid cultivars with rich violet to purple flowers are "Bluestorm," "Mood Indigo" and "Storm Cloud."
Identifying white-blooming lily-of-the-Nile plants is quite absolute. Here are names of varieties bearing snow-white to creamy white blossoms: "Alice Gloucester," "Bressingham White," "Snowy Owl," "Albus," "Rancho White" (also called "Rancho" or "Dwarf White"), "Peter Pan Albus" and "Snowstorm."