How to Grow Agapanthus

Agapanthus  are great showy, garden flowers with tall stems and exotic looking flowers in striking blue, mauve, white and pink. Agapanthus are perennials, some are evergreen others deciduous.  Growing Agapanthus is not difficult,  getting them to flower  is more tricky. The ideal growing conditions are full sun with fertile, moist but well-drained soil.

Agapanthus are rated amber wheelbarrow as medium difficulty to grow. It is important to select the correct variety for your garden and then to plant in the right place in your garden. Some varieties of Agapanthus will tolerate more cold and frost than others. It can take a little time to get Agapanthus to flower, although once established Agapanthus will flower for some years with no real attention. Whichever variety you select, it can take a couple of years to get them established and to flower.

Like so many of our garden favourites, when growing Agapanthus, the trick is to get the right plant in the right place and this is very much the case with Agapanthus. There are about 10 species of Agapanthus both deciduous and evergreen, but Agapanthus vary in hardiness. As a rule of thumb, the deciduous varieties are more hardy than the evergreen varieties, and the less hardy types will need a winter mulch and frost protection.

When growing Agapanthus outside, if your garden is not sheltered,  you will need to select a fully hardy variety,  such as A. Blue giant, A. Midnight blue, A. Lilliput (as you may expect a short variety up to 10cms) A. Snowy Owl with white flowers. Check when you buy, the label or website will state if the variety is fully frost  hardy. Selecting a hardy variety is essential unless your garden is sheltered and for an explanation of what is meant by hardy follow this link

If your garden is exposed, wet, and/or prone to frost, or you wish to grow a more tender variety, Agapanthus are best grown in pots so they can be moved into a unheated conservatory or greenhouse for the winter.  In colder areas Agapanthus will need shelter and winter protection.

If you live in Cornwall, or the Scilly Isles you are lucky, and can ignore this advice as Agapanthus grow abundantly, flowering freely in the milder conditions.

 

Agapanthus are an amber wheelbarrow plant as they can be tricky to get them to flower and some varieties are not fully hardy and so may need winter protection

 

How and where to plant Agapanthus

Agapanthus can be planted at any time during the growing season, ideally in spring. Plant reasonably deep to protect the plant from frost. If planting Agapanthus in a container leave room for a winter mulch to protect the plant. All Agapanthus both deciduous and evergreen varieties will survive a winter best planted in soil which is not too wet. If waterlogged the plants will suffer. For this reason, if your garden is on the wet side it may be better to plant Agapanthus in containers.  Given that Agapanthus do better with some root restriction, if planting into a container, select a container which is not too large in relation to the side of the plant. 

Agapanthus look good in containers as they are tall plant which sit well above the container and add style to a patio and are an ideal balcony plant.  Agapanthus will flower well without feeding, it is more about the right growing conditions. That said, in many areas of the UK growing conditions are not always ideal and a feed (high potash to aid flowering, such as Tomato feed,)  can only help things along.

Sharp blue Agapanthus blooms

There is plenty of garden advice to suggest that Agapanthus flower best when their roots are constricted. All the Agapanthus I have are growing are in containers and producing flowers. This is because my garden conditions are not ideal.  Previously I had Agapanthus growing the borders, but they failed to flower, struggling with the cold exposure and wet. As a result I dug them up and replanted in containers which has been  a great improvement and they flower well.  

The ideal growing conditions for Agapanthus is to be in a sheltered spot in full sun with good soil, which is not too dry and drains well. Even though Agapanthus like moisture retentive soil, perversely they will establish well in containers. If grown permanently in containers, it is advisable to divide and replant in fresh compost every few years. All Agapanthus like sun as they originate from warm climates in South Africa.  

Agapanthus are very rewarding with their striking flowers and foliage,  and easier to grow in milder areas of the country where they can be left undisturbed in the garden and will reward with many flowers year after year. Even in more exposed areas, by choosing a hardier variety and either mulching or growing in a container, Agapanthus can be grown all over the UK.

 

Agapanthus growing Wild on Tresco Scilly Isles

Agapanthus growing wild on Tresco Scilly Isles

Agapanthus do well in coastal gardens, being tolerant of salty winds, and positively thrive in Cornwall and Scillies, where they seem to grow wild.

I took the image left at Tresco in the Scilly Isles, on route to Tresco Abbey Garden. This shows Agapanthus grow abundantly and very well all along the shoreline. They are growing wild with no attention in a conditions which are ideal. Well drained soil, a mild climate  and plenty of sun. Agapanthus grow everywhere on the Scilly Isles, as is the case in Cornwall.  It is all about "right plant in the right place" and this shows that when planted in the right place Agapanthus do not need feeding to grow well. 

Conversely, in a wet exposed garden, it is possible to grow Agapanthus but almost certainly they will need to be in containers, and have winter protection. 

The Best Types of Agapanthus to grow

When selecting an Agapanthus for the garden, a good starting point is to check out those with the  RHS   AGM is a good starting point.

 This includes varieties such as A. 'Loch Hope' H6; and Agapanthus campanulatus subsp. patens H4 which is a deciduous variety, many of other varieties are H2 suitable for growing under glass only. Other varieties of relatively hardy Agapanthus include A.'Ben Hope' dark blue flowers height up to 1.2m; A. 'Blue Giant' rich blue flowers similar height;  and A. ' Blue Moon' light blue flowers growing up to 60cms. There is a hardier form of white Agapanthus ' Bressingham White' which has pure white flowers growing up to 90cms. There is also a mauve variety which is A. 'Purple cloud'  which is an evergreen with dark deep violet flowers which grows up to 1.5m.  Agapanthus 'Twister'  illustrated in the image above center is described as fully hardy although unless in a sheltered spot I would give it winter protection.

What to do if Agapanthus will not flower.

In some areas of the UK, growing Agapanthus is more of a challenge, and tricky to get them to flower each year. The Agapanthus I had growing in the ground just sulked and added very little to the border. Reluctant to throw away being such expensive plants, I dug them up and potted into large containers and two years later the flowers finally put in an appearance.  It seems with Agapanthus that if they are not flowering in pots to replant in the ground, and vice versa. It seems to work, and not to molly coddle or overfeed Agapanthus least is best. 

I can suggest if you are having problems getting Agapanthus to flower in the ground, dig them up and put into pots. Agapanthus look very effective in containers.  If you want Agapanthus flowers in the border,  you can always place the pots in the borders by digging out a space and sinking the container into the bed. I have seen this done with both Agapanthus and Dahlias to good affect and grown this way the Agapanthus are easier to lift to store/overwinter elsewhere.

Agapanthus are one of our showiest summer flowering plants, but perhaps not the easiest to grow. There are some green wheelbarrow plants, i.e easy to grow plants, check out summer flowering plants and ideas for summer planting.

How to look after Agapanthus in the winter

Looking after Agapanthus in the winter depends on both the variety you are growing, and your garden aspect. Some Agapanthus are described as hardy but in more northern or exposed gardens Agapanthus will benefit from some protection in winter. It is necessary to check the precise variety you are growing; as a general rule the deciduous varieties are more hardy than the evergreen types. The RHS new hardy ratings take into account other aspects of hardiness apart from a simple temperature reading, as the aspect is also important. Some plants may be described as hardy but if the ground is wet, (and cold)  may not survive the winter.

A winter mulch of around 15-20 cms of straw is ideal and I find strulch very good. As the evergreen varieties are more tender, they may need a fleece during the worst of the winter cold. If your garden is exposed it is best to move Agapanthus to a more sheltered spot or into the greenhouse for the winter which means growing in containers unless you like digging and can face digging them up at the end of the season to overwinter in the greenhouse.  

In all sheltered areas the more hardy varieties of Agapanthus will be fine with a mulch. In more exposed gardens, and the evergreen more tender varieties, Agapanthus will need a fleece or to be in an unheated greenhouse. The Agapanthus in the images above spend winter in the greenhouse and flower well.

The main causes of Agapanthus failing to flower are too much shade, Agapanthus are sun loving,  and dislike cold temperatures and lack of winter protection . 

 

updated 15.10.2019