Known for its abundant clusters of bell-shaped blossoms and durability in warmer climes, the agapanthus is renowned as a gardener's dream—especially those whose thumbs are less green than most. Also called the African lily and lily of the Nile, the agapanthus has an array of species variations. Whether deciduous or evergreen, Arctic Star white or African blue, this diverse and beautiful flower is sure to make any garden shine with only a little maintenance.
The agapanthus is notoriously hardy, but it does prefer to have a warm start. Be sure to plant your African lily well after the possibility of any further frost, some time in the latter stages of spring. The soil temperature should be at least 50° F, and the rhizomes should be planted 2 inches deep with the pointed end facing upward.
The towering stems of the agapanthus are part of its beauty, with some reaching six feet. Smaller dwarf varieties only attain a height of 20 inches, but if you're unsure which type you're cultivating, it's best to assume the former and leave a minimum of 12 to 18 inches between each one. Shorter types will usually fill in the space, anyway.
As a native to Africa, the agapanthus is accustomed to warmer temperatures and a lot of sunlight. It can tolerate partial shade if it must but will flourish best in full sun. It is most apt to thrive in hardiness zones 8 through 11, which corresponds to most of the southeast U.S., but some versions can be grown in zone 7, too.
The tall stalks of the agapanthus could originally be seen blossoming along the banks of the Nile, so it makes sense that they enjoy an ample drink. Water when the first three inches of the soil is dry, approximately once a week. Be sure that the surrounding soil is well-aerated to allow for proper drainage, and withhold water if you begin to notice any yellowed leaves.
Although it does have a few predators, agapanthus enjoys a relatively pest-free existence. Snails and slugs are likely to feast on this lily's leaves if given the opportunity, but they can be deterred by simply picking them off or placing a thin layer of copper wire around the perimeter of the bed.
Though low-maintenance, the agapanthus is susceptible to a few diseases. Botrytis may cause brown or gray lesions on the plant and prevent the flowers from opening, and powdery mildew may form gray circles around the leaves and inhibit growth. Reducing humidity and removing affected areas will resolve powdery mildew, and while botrytis has no cure, there are resistant varieties of agapanthus.
Agapanthus prefers a balanced diet, with more phosphorus than nitrogen. Feed them with 5-5-5 or 15-30-15 NPK fertilizer two or three times a year, but organic compost is best. Apply 1 to 1.5 pounds for every 50 square feet — though, with the proper starting composition, you may not need to feed them at all.
If your agapanthus is growing well, it will likely need to be divided after two or three years. You'll know it's time when you note a downturn in flower production and a general crowding of your plant. To propagate, dig out the root ball after they have finished flowering for the season, separate the ball into smaller clumps, trim back the stems, and sow the new plants with enough space for them to flourish in the future.
The bright blue and lavender petals of the agapanthus are attractive to pollinators like birds and bees, but they are not to be eaten by humans. The nectar irritates the skin, and ingestion may cause nausea, vomiting, and other intestinal problems. The African lily should be kept out of the reach of animals, as well, as potentially fatal kidney damage may occur upon ingestion.
The agapanthus is a diverse flower, coming in both deciduous and evergreen varieties. If yours is an evergreen, it will need to be brought in during the winter and kept in a bright environment in a temperature range of 55 to 60°F. If it's deciduous, it will have lost its foliage, so it can be left outside or moved to a darker location.