The agapanthus plant originates from Southern Africa, and therefore prefers a hot and sunny climate. However, it is possible to grow it successfully in a UK garden, providing you choose the right location, and offer it adequate winter protection.
If you’re prepared to put the effort in, you’ll be rewarded with spectacular displays of exotic-looking blue, purple or white flowers, at an eye-catching height. Some varieties are also evergreen, so will provide attractive green foliage year-round (if not covered for winter).
For anyone thinking about adding agapanthus to their garden, this care and growing guide should provide valuable assistance. Read on to discover how to bring these beautiful blue blooms into your garden borders.
Background, Origins & Varieties
Agapanthus is a herbaceous perennial, and part of the Amaryllidaceae family. There are hundreds of cultivars and hybrids within the genus, ranging from 20cm dwarf varieties to ones that grow to 1.5m tall.
Although it originates from Southern Africa, agapanthus has become naturalised in various other countries, including Britain and Australia. In some countries, certain varieties are even classified as invasive, for example A. praecox in New Zealand.
Agapanthus plants can be deciduous or evergreen. The deciduous varieties tend to be hardier, whereas the evergreens are more tender. It is recommended to cover evergreens in winter, or grow them in a container, so that you can bring them into a cool greenhouse to protect them from frost.
The flowers of agapanthus plants are most often shades of blue, but can also be lavender, purple or white. They are trumpet-shaped, and form in large spheres at the ends of tall stems, above the green foliage. The flower heads will attract birds and butterflies into your garden.
As well as ‘African Lily’, agapanthus is also known as ‘Lily of the Nile’ – all despite the fact that it’s not a lily. When the plant was first classified, it was incorrectly placed in the Liliaceae family.
Feeding, Care & Growing Tips
When growing agapanthus, it is important to choose a variety to suit your situation. Providing your garden is sheltered, and you don’t live in too cold an area, you should be able to grow a hardy, deciduous variety in your garden, without moving or covering it during winter. Fully hardy varieties of agapanthus include A. Midnight blue and A. Blue giant.
If you don’t have a sheltered garden, or you wish to grow an evergreen variety, your plant will probably need to be moved into a cool greenhouse or sheltered location over winter. It is therefore a good idea to grow less hardy varieties of agapanthus in containers in the UK.
Agapanthus prefers full sun, so choose a sunny, south-facing spot in your garden in which to plant it or position the container. Plant in a loam-based compost, and make sure the pot has good drainage, as the plant does not like waterlogged soil.
Water the plant regularly during the growing season of the first year – agapanthus blooms from mid-summer until early autumn, depending on the variety. Once the plant is established, it should only need watering in the case of a particularly hot or dry summer.
If you’re growing your agapanthus in a garden border, you can feed it a balanced fertiliser once a year in spring, to encourage blooming. Apply a 20cm layer of mulch to the soil in autumn or early winter, to help protect it from frost. You can also cover your agapanthus with horticultural fleece, to further protect it from the cold, especially if it’s an evergreen variety.
If your plant is in a container, feed it a liquid fertiliser every 2 weeks from April to July. Over winter (November to April), move the plant into a cool greenhouse or conservatory, or find it a sheltered spot under a wall. Note that the winter temperature should not be too warm, as this will encourage early and poor-quality flowering.
You can prune away the deadheads of agapanthus in autumn, once the flowers have begun to fade. This should help to keep the plant looking its best, and encourage new blooms. Deadhead your agapanthus by using secateurs to snip the stem with the faded flower at its base.
You can also take this opportunity to remove any dry, damaged or dead leaves and other material from your agapanthus plant, or to trim back the plant, in order to thin it out or resize it.
For deciduous varieties of agapanthus, aim to cut back the stems to around 10cm above the ground at the end of autumn. Evergreens do not need to be pruned, except for aesthetic purposes.
When To Plant Agapanthus Bulbs
The best time to plant agapanthus bulbs is in spring, around April time. Try to wait until the last winter frosts have passed – this is especially true for the less hardy, evergreen varieties. Make sure to cover the bulbs with at least 5cm of soil upon planting.
If you want to make life easier for yourself, you can also buy potted agapanthus plants in summer, from garden centres or specialist growers. Keep them well-watered and mulched, to allow the plants to establish.
Habitat & Growing Conditions
Agapanthus’s natural habitat is Southern Africa, where it grows in hot and sunny conditions, with fertile soils. Many varieties therefore do not cope well in the cold, and need to be sheltered during winter. Due to its dry natural habitat, agapanthus can tolerate periods of drought – although you should not allow it to dry out completely.
The easiest way to propagate agapanthus is by division, once the plant is fully established – usually after 4 years. Prepare for this by pruning the plant back to around half its height in the autumn before you want to propagate it.
To divide, carefully dig the plant up with a trowel, and divide the fleshy white root ball into smaller clumps, making sure each clump has some roots and leaves. Propagating in this way means that each new clump will be identical to the original plant.
Another way to propagate agapanthus is from seed, which can be harvested after the growing season. In contrast to the division method, propagating by seed will produce entirely unique plants.
Common Diseases & Problems
One of the main problems to watch out for with agapanthus is Agapanthus gall midge. The feeding activities of this small fly’s larvae specifically affect agapanthus, causing deformed and discoloured flower beds, and preventing flowering.
An infestation is most likely to affect your plant from June to September. As well as the above symptoms, you may also notice the creamy yellow 3mm maggots, crawling around inside your plant’s buds.
Agapanthus gall midge is a fairly recent discovery in the UK, and as such, not much is known about it. The current best advice on how to control it is to remove any infested flower heads, or even to completely destroy any badly infested plants. Research is currently in progress, so chemical and biological controls may become available in the future.
You should also keep an eye for fungal infections in your agapanthus, such as grey mould and root rot, which can be caused by too much moisture in the plant’s environment. Help to prevent these issues by increasing the flow of air around your plant, and ensuring the soil has good drainage, so it does not become waterlogged.
Other than these issues, some of the most common problems with agapanthus are frost damage and problems with flowering. Winter damage can be prevented by covering border plants with horticultural fleece, or by moving container plants inside.
Flowering problems can be caused by a variety of factors, including cold weather and lack of sunlight. Keep the plant in a sunny spot, and try to encourage blooming for the following year by watering your plant well in late summer and autumn. You should also water it well the following spring, and apply liquid fertiliser.
Another reason for poor flowering might be if the plant has been disturbed too much, for example by moving pots, or excessive division. Try not to move your plant any more than is necessary – repotting is only required every 2 to 3 years.
Frequently Asked Questions
When do agapanthus flower?
Agapanthus plants have a relatively long flowering period, which stretches from mid-summer until early autumn. The exact month they begin flowering may be June, July or August, depending on the variety, and the growing conditions.
Are agapanthus hardy plants?
How hardy your agapanthus plant is will depend on which variety you are growing. Generally speaking, deciduous varieties of agapanthus are hardier than evergreen varieties.
Once established, there are some deciduous varieties which require very little ongoing care, and can tolerate cold temperatures down to -5°C, or even -10°C. In contrast, evergreen varieties will need to be mulched, covered or moved inside during winter, to protect them from frosts.
What colours do agapanthus come in?
Agapanthus flowers come in all shades of blue, purple and white, ranging from sapphire and indigo, to pastel blue, lavender, pink and cream. The plants have strappy green foliage, and stiff, upright stems.
You can encourage your plants to produce high-quality, colourful blooms by watering well in autumn and spring and feeding with a high potassium fertiliser. Make sure they have enough access to sunlight and provide them with shelter over winter.
Should I deadhead agapanthus?
You can deadhead agapanthus once the flowers have begun to fade, but before they set to seed. Simply remove the faded flower heads by using secateurs to snip the stems at their base.
Deadheading should redirect energy assigned for creating seed heads and encourage your plant to flower for longer. Of course, if you prefer the look and texture of seed heads, you can leave the plant as it is.
What should I do with agapanthus when they finish flowering?
When your agapanthus plant has finished flowering, remove the dead flower heads. At the beginning of November, prepare less hardy varieties for winter by covering them with horticultural fleece, or moving them to a more sheltered location. Some plants may need to be brought inside, to protect them from frost.
How can I make my agapanthus bloom?
Problems with agapanthus blooming are fairly common, and there are several things you can try to encourage flowering. Watering your agapanthus plant well in late summer can help to encourage blooming the following year, along with watering in the spring, and applying a high-potassium fertiliser.
Make sure your plant is getting plenty of sunlight, and that it has adequate shelter over winter, to prevent frost damage. If you’re growing your plant in your garden, try moving it into a container, as restricted roots will encourage flower growth, as opposed to leaf growth.
If your plant is already in a container, try not to re-pot or divide it too often, as agapanthus plants like to be cosy, and don’t flower well when over-disturbed. Re-potting once every 2 – 3 years should be more than enough.
What is the best sized pot for agapanthus?
Depending on the variety, most single agapanthus plants can be grown in a container which measures 20cm in diameter. It is important to make sure the pot is not too large, as they prefer their roots to be constricted. Smaller varieties can be lumped together, to keep them snug.
Use a loam-based compost with some coarse sand or gravel mixed in, to give your plant the best start. Position the root ball around 5cm below the top of the pot and fill it in with compost. Water well and mulch the soil, to encourage moisture retention.