How to grow agapanthus
Agapanthus produce large spherical flowerheads, usually in beautiful shades of blue, from midsummer onwards. Above clumps of strappy foliage they sway on tall stems. Whilst the evergreens may not be fully hardy, some of the deciduous varieties can withstand most of our British weather down to -10°c.
Before choosing an agapanthus to plant consider where the plant is to be sited and its hardiness. Do you have a small & sheltered cottage garden yard in Dorset or an exposed large garden in the Scottish Highlands? Consider growing these in pots if the latter, you can move them to a sheltered location when times are cold.
Grow agapanthus in well drained soil in full sun. As with many perennials avoid planting in shade as they won't flower as much.
Agapanthus love growing in pots and containers. A fully mature plant can take up to a 1 metre pot but younger plants should have around 50% growing space around the root ball. As they are sun lovers and frost haters the pots can be moved around to suit their needs. They don't mind being rootbound and do not succumb easily to drought, which can be a problem for many plants in pots.
Agapanthus do grow very well in borders and beds but due to their drought tolerance, their willingness to be rootbound and their temperament for cold we'd recommend pots over going in the ground every time. Save that valuable space for something more suitable.
Water agapanthus regularly through the active growing season. Once they are established though they will need very little water.
They benefit from a weak liquid feed when they start growing in spring and a further feed when the blooms are about to appear. Blood fish and bone will really bring the blooms to life!
Deadhead the flowers when they are fading and when they are trying to set seed, this will prevent the plant expending energy otherwise set for producing a bigger plant next year.
The leaves can be removed as they turn yellow and die back. Most agapanthus retreat to safety underground overwinter for dormancy.
Agapanthus can easily be grown from seed and you can have flowering plants in as little as two years. Collect the ripened seeds from the browning seedhead and sow straightaway in a seed tray. Once they have strong roots and shoots they can be pricked out and potted up individually. Remember that agapanthus do not grow true from seed and the resulting plants will be different from the parent plant. In fact, you could get a true gem by doing this!
Established clumps can be divided with a sharp shovel and replanted to become new separate plants. The best time to do this is in March and April. The benefit of doing it this way is that you will get exact copies of the plant that you already have.