There’s nothing better for an infusion of midsummer blue than an agapanthus, but they come in a huge range of colours and heights from almost-black through to purple, from French navy to royal blue, through to subtle lilac, grey and pure white.
These South African bulbous plants have been selected and hybridised from only six to fourteen species, depending on which botanist you believe. The name, agapanthus, translates as ‘love flower’ but they’re more commonly known as the African lily.
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Evergreen or deciduous agapanthus?
The agapanthus’ other common name, Lily of the Nile, is misleading for they don’t grow near the River Nile. All the species are found in South Africa and some are evergreen (Agapanthus africanus and Agapanthus praecox) and others deciduous, depending on which side of the Cape they grow on.
The Eastern side of the Cape has a wet summer season lasting four months, between November and February, when rainfall averages 5 inches per month (125m). The winters, between May and August, are dry and cool however. As a result agapanthus species found on the eastern side of the Cape tend to do their growing in the summer and then die down in winter. This deciduous habit makes them hardier than the evergreen agapanthus.
The western Cape has a Mediterranean climate with moist damp winters, between May and August, followed by a dry summer between November and January. Agapanthus species on the western side grow in winter when moisture and warmth is available so they like to keep their foliage in winter, but are not generally as hardy as the deciduous types.
The other thing to be aware of is that native agapanthus experience abundant rainfall in one season of the year, whether deciduous or evergreen, and this promotes growth. In other words they are thirsty plants so British gardeners need to water agapanthus well during between April and August, especially if they are in pots. The myth that agapanthus do well if you neglect them and starve them is entirely wrong. They respond to both water and food and a liquid high-potash tomato food applied every two weeks will pay dividends.
Where to grow agapanthus
South Africa is a rugged country with high light levels because sunshine hours average between 8 and 10 hours every day, so your agapanthus needs a sunny position that gets maximum daylight.
The thick petals and rubbery stems resist strong winds and strong sunshine and the darker-coloured forms have lots of anthocyanin, the blue pigment. The flowers, which are bee-friendly, last many weeks and they cut well. Don’t allow them to run to seed, always cut the spent flower heads off.
White agapanthus in a border at Kew Gardens.
How to grow and care for agapanthus
Growing agapanthus in a border
The fleshy roots of agapanthus can suffer frost damage in severe winters, so if you’re planning to grow agapanthus in a border the ground must be well-drained and sunny. A strip close to a sunny house wall is ideal as long as you remember to water your agapanthus well in the growing season.
Choose a variety with a deciduous tendency and mulch, or fleece young plants in their first two years if severe weather strikes. A top dressing of coarse grit or pea gravel also helps drainage.
Once established clumps of deciduous agapanthus can withstand -10ºC to -15ºC as long as the ground is well drained, although the number of flowers can be reduced after a hard winter. Plants generally recover after hard weather though.
Dark-flowered varieties, verging on black, tend to be shy flowerers.
Find out how to design and plant a herbaceous border
Growing agapanthus in pots
The choice is far wider when you opt for growing agapanthus in pots, because hardiness becomes less of an issue. Agapanthus look more impressive in pots too, because they are raised up above the pot and therefore reach four to five feet. They are also moveable feasts, so you can use them as eye catchers in front of borders that may have passed their best.
It’s important to choose rugged pots, because your plants will be in those pots for three years on average, before you have to divide them. Terracotta is ideal.
Make sure your pots have almost straight sides, because tapered lily pots and tall slender pots will blow over.
Use John Innes no 2 compost and, when you buy a new agapanthus, use a pot that’s just slightly larger than your plants. They struggle if there’s too much space round their roots.
Once they’ve filled the pot repot them. Spring is an excellent time if you can catch them just as they’re thinking about growing.
You’ll need to feed and water your agapanthus once they begin to grow. An unheated greenhouse gets them going faster.
Move them outside, choosing a sheltered place, in early May.
After flowering, it’s best to remove the seed heads so that your choice plant puts its energy into getting larger rather than producing babies.
Ease off the watering and feeding in early September and allow the plant to dry out.
Move under cover in October. A shed or greenhouse is usually sufficient. Or you can lay your pot on its side and place it somewhere sheltered - against the wall of the house. You don’t want winter rain and snow to reach the roots.
Find out about winter care of pots
Feeding and watering agapanthus
Water agapanthus well between April and August to mimic the wet season in their native South Africa.
Agapanthus will also benefit from a fortnightly feed of liquid high-potash tomato food during the growing season.
Reduce watering and feeding in September and allow the plant to dry out.
Deadhead agapanthus after flowering to allow the plant to conserve energy and stop it self-seeding.
Large clumps in the border should be lifted in spring every 4 - 6 years, split into pieces, and then replanted.
Plants in containers should be potted on every 2nd year into slightly larger pots.
When tubs become full the rootstocks can be difficult to divide because getting them out of the pots is a challenge.
Tackle the job in March before you start watering them and then split the clump with a small saw or knife.
Pot up again, making sure that the perhaps four sections of the original clump go back in. Agapanthus will only produce leaf if there’s too much room in the pot.
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Agapanthus varieties clockwise from top right: 'Purple Delight', 'Arctic Star' and 'Tarka' photographed by Richard Loader.
Good agapanthus varieties
Agapanthus varieties for growing in the ground
These varieties of agapanthus are hardy to -15C once established.
This an old variety named over forty years ago by plantswoman Lady Priscilla Bacon of Raveningham Hall in Norfolk. She visited South Africa many times and Steven Hickman, who has a Plant Heritage collection in Yorkshire and a specialist agapanthus nursery (see below), rates this dark-blue deciduous variety as terrifically hardy and floriferous. 75cm /2.4ft.
A white, semi-evergreen British-bred agapanthus with grey-green foliage. It’s very hardy in well-drained borders, but take note. The flowers of white-petalled varieties do not last as long because they have less pigment in their petals. 60cm/ 2ft.
This narrow-leaved variety, selected and named by Dutch plantsman Coen Jansen, produces lots of dark-violet to purple flowers flowers on strong green stems. Most dark agapanthus are shy to flower: this one’s an exception. 70cm/ 2.2ft.
A Yorkshire-bred variety selected for outdoor hardiness and flower power by Steve Hickman, although it’s also good in a pot. The powder-blue flower heads of this deciduous variety have dozens of flowers neatly arranged into a dome-shaped head and each flower is darkly lines and shaded. 90cm/ 3ft.
A bicolour agapanthus with flowers in white and blue. Hardy, so ideal for borders. 80cm/2.6ft.
A pure white clump-forming agapanthus that's best in a sunny, sheltered spot. 80cm/2.6ft
Good agapanthus varieties for pots
Bred close to Dartmoor in Devon, by Dick Fulcher the holder of one of the Plant Heritage collections, this is my desert island agapanthus because it’s so willing to flower. Each mid-blue flower has a dark midrib, so it’s dazzling, and the foliage is neat and attractively dark at the base. The heads of flower are globular and the stems are strong. 1m/ 3-4ft .
A very useful, shorter agapanthus because it flowers roughly from August onwards -extending the season. Raised by Dick Fulcher, near Dartmoor in Devon, the lavender flowers have a dark midrib. 60cm /2ft .
‘Hole Park Blue’
This has been the last agapanthus to flower on the ongoing RHS agapanthus trial which can be seen at RHS Wisley up until 2018. It’s an evergreen Kent variety, named by Edward Barnham, and it’s been grown in this garden for over one hundred years. 1m/ 3.2ft.
A substantial, statuesque grey-to-silver, semi-evergreen agapanthus that looks sensational on a hot day and in evening light, when it appears to develop a pinkish tinge. It’s very subtle, soft and stylish and the large flower heads have between 70 to a hundred long-trumpeted flowers that point slightly downwards. Easy 85 cm/ almost 3ft or more.
This agapanthus produces very round, symmetrical flower heads held on green stems above even greener evergreen foliage, so it’s a very vibrant affair. 90cm/ 3ft.
A short New Zealand variety, with small heads of bright-blue flowers. It produces lots of bright-blue flowers over many weeks. The flowers are held on splaying stems that reach up to two feet. 50-60cm/ up to 2 ft.
A beautiful bicolour (white and blue) variety from Australia. Up to 100cm/3.2ft.
A dwarf evergreen variety with beautiful golden variegated foliage and globes of blue flower. 50cm/1.6ft.
Agapanthus 'Snowstorm' (or 'Snow Storm') is a compact variety that's ideal for pots or planting in drifts. Large masses of white flowers from June to September. 70cm/2.2ft
Agapanthus can be bought as bulbs or containerised plants.
Steven Hickman - Hoyland Nursery - www.somethingforthegarden.co.uk
Fairweathers Nursery - www.fairweathers.co.uk
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