With their strong stems and beautiful large heads, agapanthus make a structural and graceful addition to any border. I also love agapanthus in a series of pots down a path or around the edge of a terrace.
Soil and Site
Agapanthus grow best in well-drained soil, in a sunny site that receives sun for most of the day. On heavy soils, mix in grit when planting.
30cm apart and with crowns 5cm (2in) below the ground.
In the garden
Agapanthus have fleshy roots and leaves and this can make them prone to frost damage. The deciduous varieties are hardiest, dying down in winter. Once they are established, they should all withstand most conditions.
Evergreen types are more tender and their leaves can be damaged by frosts. Therefore, a mulch of straw or fleece is advisable when young plants are establishing or extreme cold (below -5ºC) is forecast. Established clumps of evergreen Agapanthus can withstand -10ºC to -15ºC if the ground is well drained, but the number of flowers maybe reduced the following summer. Planting in beds against house walls can reduce the likeliness of frost damage.
Agapanthus are well suited to being grown in pots, especially the evergreen varieties which can then be brought into a conservatory or greenhouse for the winter. Use a loam based compost like John Innes No3 with slow release feed granules added for long term feed. Ensure that you feed with during the growing season.
Agapanthus doesn't like to be potted into pots that are too spacious as this will encourage leaf growth rather than flower production. Ideally, they perform best where root development is restricted but the plants are well watered and fed.
Feed weekly or fortnightly with a balanced liquid feed during the growing season until flowers begin to show colour.
Although plants flower well in pots if the roots are constricted, they should not be allowed to become completely root bound and should be split and replanted in fresh compost if the roots become too congested, otherwise flowering will suffer.
It may take two or three years for plants to establish before flowering really takes off, but after this they will grow in to long-flowering clumps.
Agapanthus can be reluctant to flower if subjected to drought conditions after flowering. To ensure a good display the following year, keep plants moist until autumn after flowers start to fade, which will encourage the development of new flower buds.
Cut down spent flower stems unless you are drying them to use for decoration.
Mulch in autumn or cover the crown of the plant with straw or fleece to protect from cold. If clumps become too big, they can be lifted and split every four to five years.
Cut the stems at a 45 degree angle with a sharp knife. Fill sterilised buckets with luke warm water and add flower food. Place the agapanthus in the buckets. Leave over night to condition before using. Place away from direct sun light, radiators and drafts. Keep the agapanthus in a cool place. Watch Sarah's video guide for A Simple Arrangement of Agapanthus.