Agapanthus are perennials with fleshy, rhizomatous rootstocks 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. The evergreen species originate mainly from areas with winter or year-round rainfall, such as the East or West Cape. Deciduous species grow mainly in areas with dry winters and moist summers.
Agapanthus thrives in fertile, well-drained, but moisture-retentive soil in full sun. Agapanthus show no preference for pH, except A. africanus which prefers an acid soil. 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. Alternatively, in colder districts the more tender evergreen types can be grown in containers and moved to a frost-free greenhouse or conservatory for the winter.
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. For single plants 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 or greenhouse is ideal. Avoid overwintering in warm conditions or overpotting, as this can reduce flowering.