Are you ready to add an exotic blue flower to your summer patio display, and then keep it as a houseplant? Lily-of-the-Nile is used extensively in landscaping in mild climates, but it’s not any harder to grow this plant in the north than many other tropicals. Learn more about the tender perennial Agapanthus in this article...
Agapanthus is a genus of six species of fleshy-rooted perennials with a long history of taxonomic confusion. It was originally included in the lily family (Liliaceae), was then moved to the amaryllis family (Amaryllidaceae), moved again into the onion family (Alliaceae), went back to Amaryllidaceae and now resides in its own family, the Agapanthaceae, a sister family to the Amaryllidaceae. Despite the common name of Lily-of-the-Nile, they are not native to the Nile River basin of northeastern Africa; this monotypic family (consisting of only one genus) is actually endemic to southern Africa. In its native areas, Agapanthus is considered to be both a magical and a medicinal plant, used to treat heart disease, paralysis, coughs, colds, and other ailments, and the leaves are used as bandages (the plant does contain chemicals with anti-inflammatory and other properties). However, the plant’s sap can cause minor irritation or dermatitis in susceptible individuals, and will cause severe pain in the mouth if ingested.
The first plants were brought back to Europe in 1679 by the early explorers to South Africa. They are grown for the spectacular blue spherical flower clusters in early to mid-summer. There are two species of Agapanthus, along with many hybrids, which are commonly used as landscape plants in mild areas or houseplants in colder climates. The dwarf forms are especially good as container plants, as restricted root growth induces heavier flowering.
This tender herbaceous plant grows in upright clumps from fleshy rhizomes that produce short, tuberous roots. Tufts of leaves are produced on short stems. The arching, strap-like leaves are 12-24” long and 1-2” wide. The dark, glossy green leaves are attractive even when the plant isn't flowering (some species have bluish leaves or are lighter green in color). Most of the common types are evergreen, but there are some that are deciduous. The evergreen ones shed a few of the older, outer leaves every year and grow new leaves from the growing shoot.
Flowers clusters are borne on sturdy, erect stems held well above the foliage. Each single terminal inflorescence consists of numerous tubular to bell-shaped flowers, each with 6 parts. There are 20 to 100 flowers in each rounded umbel, depending on variety and species. The individual flowers look like a miniature lily flower, often with darker stripes down the middle of each tepal (3 petals and 3 sepals that all look the same). Flower color ranges from deep violet-blue to pale shades of blue, as well as pure white. They bloom primarily in summer, although in frost-free climates they will bloom over a longer season. The flowers also make good cut flowers, and the dried seed heads can be used in arrangements.
Agapanthus makes quite a show in a large container on the patio, and can add an exotic touch to any planting scheme. The blue flowers of Agapanthus combine well with lemon-yellow flowers, such as daylilies, marigolds or lantana. For a flashier combination, pair them with potted cannas with bright yellow and/or orange flowers. For a more subtle and elegant effect, combine them with silver- or blue-leaved foliage plants, such as dusty miller or honeywort (Cerinthe major). For a tropical look, place them with other containers of palms, banana plants and hibiscus.
Grow Agapanthus as a houseplant in bright light and average temperatures. Keep well watered when growing, but allow it to dry out in winter. This plant blooms best when grown in full sun and pot-bound, so don’t divide or replant until the plant is pushing out of its pot. Potted plants can be moved to a sheltered spot outdoors after all danger of frost is past in spring, but be careful to acclimate it gradually to full sun to prevent sunburn. Bring inside at the end of the growing season, before frost.
Evergreen types should be grown year-round, treating them as houseplants during the winter. The deciduous ones can be stored in a cool, dark place (above freezing). They can be kept in their containers, just allowing them to remain dry until spring, or the tuberous roots can be dug up, the soil removed, and wrapped in newspaper for storage.
Plant Agapanthus just deep enough to cover the roots, spacing them about 8” apart. A single plant will fill a 12” pot, or use more in larger pots. Use well-drained potting mix, as they do not tolerate waterlogged soil. During the growing season, containers can be fertilized lightly; overfertilization will result in lanky growth.
Agapanthus can be propagated from seed or division. Seed should be sown in spring; germination usually takes 1-4 months. It will take 3-5 years to flower from seed. Root bound potted plants can be divided every 4-5 years. Division is best done after flowering, but it can be done any time. Use a very sharp knife to cut the clump into sections, each with roots attached, and pot the sections up. Divisions may not flower until the following year. Commercially selected clones are propagated by tissue culture.
There are two evergreen species (A. africanus and A. praecox) and four deciduous species (A. campanulatus, A. caulescens, A. coddii and A. inapertus), but few of these are commonly available as ornamentals (and not all nurseries follow this most recent classification so you may see other species names used). There are numerous hybrid cultivars with a range of characteristics and sizes hardy in zones 7-11. Because Agapanthus species hybridize readily with each other, especially when grown in close proximity, many of these garden hybrids are of undocumented parentage (not to mention the confused taxonomy of this group). Some include:
- 'Albus' – a white-flowered selection of A. africanus
- ‘Baby Blue’ – a dwarf cultivar with bright blue flowers on 12-16” tall stems.
- 'Back in Black' – a new cultivar with very dark blue flowers on dark stems.
- ‘Blue Triumphator’ – one of the most commonly found deciduous types.
- 'Bressingham Blue' – dark violet blue flowers to 4 feet. Also a white version, 'Bressingham White'
- 'Elaine' – upright and vigorous selection of A. africanus, with deep purple-blue flowers on 4 ft. stems.
- ‘Ellamae’ – bright violet-blue drooping flowers on stems 3-5 feet tall.
- 'Getty White' – medium sized with large clusters of white flowers on 2-4 foot stems.
- ‘Headbourne Hybrids’ – a deciduous group developed in England in the late 1940’s, with plants up to 30” tall and flowers in various shades of blue. Many hardy varieties were then bred from these. Hardy in zones 6-9.
- ‘Lilliput’ – dwarf, dark blue flowers on 18" tall stems.
- Midknight Blue™ (‘Monmid’) – deep, violet-blue flowers on 36” tall stems.
- ‘Mooreanus’ – pale blue flowers.
- ‘Peter Pan’ – a vigorous dwarf variety (8-12”) with large clusters of mid-blue flowers on 1-2 foot stems.
- ‘Queen Anne’ – clump to 12” tall with bright blue flowers on 24” tall stems (A. africanus).
- ‘Rancho White’ – white tubular flowers on stems to 18” tall.
- 'Snow Cloud' – rounded umbels of small, pure white flowers on 4 ft stems.
- Summer Gold™ – a selection of A. africanus with yellow variegated foliage and powder blue flowers on 30" stems.
- ‘Storm Cloud’ (= 'Purple Cloud') – intense purple-blue flowers on 4 ft stems
- 'Streamline' – open flowerheads of mid-blue on dwarf plants.
- ‘Tinkerbell’ – a sport of ‘Peter Pan’ with variegated leaves (edged with creamy white) 6-8” long and pale blue flowers on 18” tall stems. It is slow-growing and does not bloom reliably, so is best grown for the foliage.
- Agapanthus orientalis – University of Florida Extension fact sheet FPS-18
- Agapanthus.org.uk – a British site devoted to these flowers
– Susan Mahr, University of Wisconsin - Madison