Agapanthus (African lily) are summer-flowering perennial plants, grown for their showy flowers, commonly in shades of blue and purple, but also white and pink. They thrive in any well-drained, sunny position in the garden, or grow these beauties in containers.
Agapanthus are herbaceous perennials originating from Southern Africa. Both deciduous and evergreen, some have thick, strappy leaves and others grass-like foliage. They range from fully hardy to half hardy, with the evergreen varieties generally the most tender.
Agapanthus thrives in fertile, well-drained, but moisture-retentive soil in full sun. Plant crowns in spring, 5cm (2in) below the ground and avoid planting in shade, as plants will either grow poorly or develop a mass of lush foliage at the expense of flowers.
Both deciduous plants and the more tender varieties with evergreen leaves are best protected over winter with a dry mulch of sand or straw. Apply a 15-22cm (6-9in) deep layer around plants in autumn or early winter and remove in spring before growth starts. A few layers of horticultural fleece can also be thrown over the leaves of the evergreen varieties.
For the best flower displays, feed weekly or fortnightly with a balanced liquid feed during the growing season until flowers begin to show colour. Water agapanthus plants regularly during the growing season, but only sparingly in winter.
If your soil is prone to winter waterlogging, or you live in a cold area and want to grow tender varieties, try growing agapanthus in large containers. Choose pots 20-23cm (8-9in) in diameter and fill with John Innes No.2 or No.3 potting compost. Place in a light, dry, frost-free place in late autumn - a cold frame, greenhouse or conservatory is ideal. Do not overpot agapanthus, or there is a risk they may not flower.
Agapanthus are easy to propagate by division. Divide between spring and early summer, or in early autumn, after plants have finished flowering. Avoid splitting plants too often as this will reduce flowering. Large clumps should only be split every four to six years.
Agapanthus species (not named cultivars, as these will not come true to type) can be propagated by seed. Collect pods as they turn brown in autumn and allow them to split apart indoors. Store in a cool, dry place and sow in the spring.
There are a good number of agapanthus to choose from in the RHS Plant Selector. Here are three to consider;
- Agapanthus africanus AGM - half hardy, evergreen, acid soil, deep blue flowers
- Agapanthus campanulatus ‘Albovittatus’ - fully hardy, variegated, pale blue flowers
- Agapanthus ‘Loch Hope’ AGM - hardy, narrow leaves beneath deep blue flowers
RHS Plant Finder
Agapanthus have few problems, although frost damage is a common issue in cold winters, even for the more hardy types. A poor display of flowers and pale streaks on the leaves can be a result of virus and plants that have these symptoms are often best replaced.
Agapanthus can be shy to flower if subjected to drought conditions following flowering. To ensure a good display next year, keep plants moist until autumn after flowers start to fade, which will encourage the development of new flower buds.
There is a common misconception that agapanthus flowers better when pot-bound. Although they like to be cosy in the pot, flowering poorly when over-potted or over-divided, they also flower poorly when excessively pot-bound. Try repotting, plus watering and feeding in spring, to improve flowering.
Too much shade, cold weather and lack of winter protection are also common reasons for agapanthus to fail to flower.
Common name African lily
Botanical name Agapanthus
Flowering time Mid-summer to early autumn
Planting time Spring or early autumn
Height and spread 40cm-1.5m (15in-5ft) height, 30-60cm (12-24in) spread
Aspect South- or west-facing
Hardiness Half hardy to fully hardy