Lily of the Nile (Agapanthus)

African Lily, Lily of the Nile

If you don’t yet know agapanthus, you likely recognize it. Agapanthus is a graceful darling of ornamental gardens around the world — and for good reason. When agapanthus bloom in midsummer, they light up the landscape like sparklers, levitating among the fireflies.

I. Appearance and Characteristics 

Agapanthus is a genus of plants, the only one in the subfamily Agapanthoideae of the family Amaryllidaceae. The family is in the monocot order Asparagales. The name is derived from Greek: ἀγάπη (agapē – “love”), ἄνθος (anthos – “flower”).

Some species of Agapanthus are commonly known as lily of the Nile, or African lily in the UK. However, they are not lilies and all of the species are native to Southern Africa (South Africa, Lesotho, Eswatini, Mozambique), though some have become naturalized in scattered places around the world (Australia, Great Britain, Mexico, Ethiopia, Jamaica, etc.).

Species boundaries are not clear in the genus, and in spite of having been intensively studied, the number of species recognized by different authorities varies from 6 to 10. The type species for the genus is Agapanthus africanus. Many hybrids and cultivars have been produced. They are cultivated throughout warm areas of the world. They can especially be spotted throughout Northern California. Most of these were described in a book published in 2004.

Agapanthus is a genus of herbaceous perennials that mostly bloom in summer. This leads to the Australian common name, Star of Bethlehem, as it blooms just before Christmas. The leaves are basal, curved, and linear, growing up to 60 cm (24 in) long. They are rather leathery and arranged in two opposite rows. The plant has a mostly underground stem called a rhizome (like a ginger ‘root’) that is used as a storage organ. The roots, which grow out of the rhizome, are white, thick and fleshy.

The inflorescence is a pseudo-umbel subtended by two large deciduous bracts at the apex of a long, erect scape, up to 2 m (6.6 ft) tall. They have funnel-shaped or tubular flowers, in hues of blue to purple, shading to white. Some hybrids and cultivars have colors not found in wild plants which includes bi-colored blue/lavender and white flowers flushed with pink as the blooms mature. The ovary is superior. The style is hollow. Agapanthus does not have the distinctive chemistry of Allioideae.

II. How to Grow and Care

Sunlight

Agapanthus plants grow best in full sun and need six to eight hours of sun a day for the best bloom production. However, in extremely hot climates, they benefit from partial shade.

Temperature and Humidity

Many agapanthus species are evergreen in tropical climates. The non-evergreen types require a little more protection and warmth during the cool season. As fall arrives, initiate their dormancy by withholding some water. Move the more tender evergreen varieties into a frost-free environment, like a greenhouse or near a bright window in a home. Hardier plants can be left out and sparsely watered until spring. Agapanthus can handle high humidity but does not require it.

Watering

Water regularly to provide 1 inch per week until plants are established, then reduce the amount to 1/2 inch per week. Agapanthus are drought resistant and won’t tolerate standing water. Significantly reduce or eliminate watering in winter until new growth begins the following spring.

Soil

Agapanthus is tolerant of soil type but grows best in fertile, light, sandy loam with good drainage. Agapanthus africanus prefers slightly acidic soil with a pH between 5.5 to 6.5 but other species grow well in a neutral soil pH of 7.0.

Fertilizing

Since agapanthus plants are frequent bloomers, it’s a good idea to fertilize them twice a year—in early spring and again two months later. Give them a balanced granular fertilizer such as 10-10-10 or one slightly higher in phosphorus than nitrogen to keep the blooms going all season long. for the amount to use, follow product label directions. Be sure to water it in well.

Planting Instructions

Plant bare-root agapanthus in the late fall in warm climates or in the spring after the last frost in cool climates. In the garden, plant the rhizomes 12 to 24 inches deep in moist, well-draining soil. The root crown should be facing up and positioned at soil level.

If you have a nursery plant, dig a hole in the garden as deep as the nursery container and twice as wide. Loosen the soil in the bottom of the hole. Wear gloves to remove the plant from its container and gently loosen the roots with your hands. Set it in the ground at the same level as in the container. Backfill the hole and press down to remove air pockets. Water the plant. Spacing guidelines for multiple plants will depend on the variety you’ve selected. Consult the tag that came with your plants to ensure proper placement.

Agapanthus can also be grown in containers filled with potting soil.

Pruning

Remove damaged leaves any time of year, but leave all the others on the plant so it can store the energy it needs for the following year. For agapanthus grown in the ground, cut back the foliage to about 4 inches in late fall when blooming is over. The plant will go dormant for the winter. Mulch the crown of the plant to protect it.

During the blooming season, remove faded blossoms from the stem to encourage new growth and prevent the plant from wasting energy on seed production.

Propagation

Agapanthus is easily and most reliably propagated by division. Garden-grown plants should be divided every four to six years. Potted plants bloom better when root-bound and a good rule of thumb is to divide and re-pot every four to five years. Division is accomplished best in early spring for deciduous plants and in autumn after blooming for evergreen varieties.

Tools you need to divide agapanthus include a shovel, hand shears, a sharp knife, and gloves.

  • Choose a clump of agapanthus and use shears to cut foliage down to six to eight inches for easier handling.
  • Use the shovel to dig around the clump 6 inches from the center and eight inches deep
  • Lift the clump and shake soil from the roots, removing as much as you can.
  • Grasp 1/2 of the clump at the base in each hand and gently pull apart the plants and attached roots. They should separate easily. If necessary, use a sharp knife to cut through the bottom of the root ball to separate plants.
  • Divided plants that were difficult to divide should be cured to heal over for several days before replanting. Plants that divide easily can be immediately replanted in a new location in the garden.
  • Dig a new hole, wide and deep enough to accommodate plant roots, Place each division 12 to 18 inches apart.
  • Withhold water for several days to allow plants to settle.

How to Grow from Seed

Seeds are easily collected from dry brown pods that mature in late summer and early autumn. The seeds are short-lived, so sow them immediately. Note that collected seeds might not produce plants identical to the original. Agapanthus seeds are also available for purchase. Plants grown from seed can take three to five years to produce flowers. To propagate from seed, gather seed trays, and seed starting medium.

  • Fill seed trays with a moistened, well-draining seed starting medium.
  • Soak seeds for several hours before planting. (This step is optional; soaking speeds up germination slightly.)
  • Place seeds on top of the medium and cover lightly with medium or grit. Agapanthus seeds need exposure to light for germination.
  • Water lightly and place in a sunny location with temperatures between 68 and 86 degrees Fahrenheit.
  • Keep soil moist but not wet.
  • Germination occurs in about one month. Move sprouts to a cooler location (around 58 degrees Fahrenheit) but maintain bright light.
  • Once the root structure is well-developed, pot up into 12-inch pots or plant out in the garden after the final frost.

Potting and Repotting 

A good tip for proper care of potted agapanthus is to divide the plants on a regular basis. In general, agapanthus plants don’t mind being snugly planted in a pot. However, they appreciate being divided every few years to encourage new growth and increase blooms.

Overwintering

Agapanthus are tough plants but winter hardiness is a challenge, so it’s important to verify the cold hardiness of your plants, Evergreen agapanthus is unlikely to tolerate cold winter weather and should be either heavily mulched or grown in pots and moved indoors for overwintering. It’s best not to overwinter them outdoors unless you live in USDA hardiness zones 9 and 10.

Deciduous, semi-evergreen, and half-hardy varieties have different degrees of cold tolerance. Deciduous agapanthus is considered half-hardy to USDA zone 6 but some hybrids might keep their leaves through winter if there’s not much frost. Rhizomes can be lifted in autumn after leaves die back, stored, and replanted in spring. Add heavy mulch to plants grown in the garden or move potted plants to a sheltered location. Water is reduced or withheld during winter months.

To store agapanthus tubers, let them cure for several days to dry. Then wrap them in newspaper and store in a cool, dark location. The ideal storage temperature is 40 to 50 degrees Fahrenheit.

Pests and Diseases

Common Pest & Plant Diseases

Agapanthus are seldom bothered by insects but can attract aphids, mealy bugs, and red spider mites. A strong spray with a hose can knock them off the plant. Treat severe infestations with horticultural or neem oil.

Fungal diseases like verticillium wilt can affect overcrowded plants. Pot up and divide plants regularly to allow for good air circulation.

Common Problems 

Yellowing Leaves

The leaves of evergreen varieties can turn yellow at the end of the growing season. This is a natural process of older foliage dying back and it can be removed. New leaves will grow from the center to replace the dying foliage.

Reduced Blooms

Reduced blooms can indicate that the plants need to be divided. Replant the newest growth and discard older plants from the center of the clump.

III. Uses and Benefits 

Incorporating agapanthus into your garden landscape can add an element of sophistication and vibrancy. Whether used as border plants, in containers, pots, or as a focal point in a garden bed, their lush foliage and stunning blooms can create a captivating visual appeal.

There are numerous plants that can make excellent companions for agapanthus. These include roses, lavender, westringia, ornamental grasses, and even edible herbs. These plants complement agapanthus not only in terms of aesthetics but also in their similar growing requirements.

For example, roses can provide showy blooms that compliment the strappy foliage and subtle flowers of agapanthus. Lavender, with its silvery foliage and fragrant flowers, can add another layer of sensory appeal. Ornamental grasses can provide movement and soften the bold structure of agapanthus, while edible herbs add a practical element to the garden design.

Lily of the Nile (Agapanthus) Details

Common name African Lily, Lily of the Nile
Botanical name Agapanthus
Plant type Herbaceous Perennial
Hardiness zone 8a, 8b, 9a, 9b, 10a, 10b, 11a, 11b
Growth rate Medium
Sunlight Full sun (6 or more hours of direct sunlight a day)
Soil condition Loam (Silt)
Flower color Blue
Leaf color Blue