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Agapanthus - Thompson & Morgan

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Agapanthus

In the first part of a two-part series Graham Gough looks at the cultivation and propagation of these dramatic plants.

The flower garden is not unlike a circus show with plants coming and going; thrilling us with their individual acts. One of the highlights comes in June when the arena seems brim-full of talented and colourful performers. But as the season wears on into July and August a certain blandness becomes apparent and so it is with some relish that we await the troupe of Agapanthus, or Africa lilies, to entertain us with their star performance.

Their qualities are manifold, the two most important being the strong vertical accent they provide, an important factor in any well-designed border, and, of course, their colour. Coming in a wide range of blue (and, as with nearly all blue flowers, white as well) they provide us with an essential contrast to the surfeit of yellow which seems to abound at this time of year.

The ease with which the gardener can grow these plants is, however, in contrast to the difficulty the botanist has in naming them, as taxonomically they are a very confused genus. With the liliaceous family having recently been reviewed, the genus Agapanthus now finds itself placed in the Alliaceae, together with Allium, Brodaeia, Ipheion, etc. In spite of what other characteristics it shares with the family, fortunately for propagators it does not have the same malodorous tendency as the main genus: the onion.

They are best described as perennial herbs (though to a certain extent this will depend on cultivation) with a short creeping rootstock and thick fleshy roots. The leaves are linear and sometimes arching. They can vary in colour between glaucous and deep green. The individual flowers are quite large and are carried on short stems in a many-flowered umbel, a single one of which can carry as many as 150 blooms. Their colour can vary from white through pale blue to a very deep, almost violet, blue. Even when flowering is over, the dying leaves can turn a wonderful buttercup colour and the dead flower heads provide sculptural winter decoration.

One has only to recall the number of gardens in which they can be seen growing to appreciate how tolerant they are of a wide range of soil, from chalk to clay, the pH of the soil seeming to be of little importance. Sadly we do not all possess the classic combination of a well-drained, moisture-retentive soil (does it really exist?), but provided that the soil is not cold or boggy during the winter months, success in growing the plants should not prove too difficult.

Growing them, however, is not the same as flowering them and for this they need the hot sun; and plenty of it. This may partly account for the reason why the British National Collection is held in Torbay, but that being said many fine cultivars have originated in Scotland and there is an impressive collection at Harlow Carr.

There are a number of species and cultivars in cultivation to choose from as a brief look through the indispensable Plant Finder shows only too clearly, but as with so many plants it pays, if possible, to see them flowering before making your choice. Selection from a catalogue is perfectly acceptable but nurserymen are not above eulogising when describing their plants!

Assuming you have purchased or been given the plant you require, ideally it would be best to plant it between April and September when the roots are fully active. Failing this optimum time it would be as well to overwinter the plant in a cold frame or greenhouse until the following year, ensuring that the pot does not freeze.

Coming from South Africa, Agapanthus receive summer rainfall and consequently enjoy moisture as much as the aforementioned sun. When planting, therefore, on a dry and hungry soil, such as chalk or sand, a liberal quantity of humus should be incorporated, preferably below the roots of the plant. A thick mulch of leaf mould will also help to improve the moisture retentive qualities of the soil as well as providing a certain amount of protection to the crowns during the winter months.

The stems of a great many forms, A. inapertus being an exception, lean towards the sun; a point to be borne in mind when siting the plants.

Should space be limited, Agapanthus are perfectly amenable to pot culture. Indeed, until relatively recent times they were treated as tender greenhouse subjects and only appeared in the open garden in pots that could be moved back inside for the winter. They are still frequently seen grown in this way as they make an extremely decorative feature, particularly on terraces where they can stand guard on either side of a doorway or at the top or bottom of a set of steps. As the containers should be taken inside during winter there is not too much problem over whether they should be frost-proof but they should still be very strong as the force of the enclosed root system is very great and can easily fracture a weak or cracked pot.

When using containers a John Innes No. 3 potting compost should provide a suitable growing medium. This should not be allowed to dry out during the growing season and will probably need watering at least once a day in the summer, particularly if they are in terracotta pots. Conversely, pots should not be over watered or allowed to freeze during the winter.

The two methods by which agapanthus can be propagated are seed and division. The latter is the simpler (but more strenuous!) of the two, and the only method by which clones can be increased. It is possible to prize or slice off pieces from large clumps with suitable tools such as forks or spades though to my mind this is a somewhat clumsy and wasteful method. A more satisfactory way of proceeding is to lift the clump and wash the roots in a bucket or under a running tap to remove the soil. Once this has been removed the propagator has much better access to the tight crown when he either pulls it apart (strong fingers required here) or carefully cuts it into suitable sized pieces using a sharp, pointed knife (here it is strong nerves that are needed!). The best time to carry out this procedure is when the plant is in active growth, namely from May onwards. There is a temptation to divide earlier than this but this can lead to heavy losses (discovered through bitter experience, alas) as the divisions tend to rot when inactively sitting in the cold, damp soil or compost.

Seed sowing offers the most exciting method of propagation as, generally speaking, no two seedlings will be alike. It was this factor that interested the Hon. Lewis Palmer (of Headboume hybrids fame) who grew, selected and distributed a large number of plants raised from seed. Whilst in South Africa he had seen a number of species in the Kirstenbosch Botanic Garden that were not in cultivation in Britain. On returning home he sent a request to the Garden for seed of the species he had seen, however, to his amazement he subsequently found that all the plants that he raised were hybrids. Thereafter he spent many years raising and selecting seedlings and a number of the clones he named still survive today. The best known were his Headboume hybrids which were instrumental in showing that many agapanthus could be safely over-wintered outside in Britain and other countries where the temperature is not too harsh (down -12C; 10F or down to zone 8).

Following Palmer's lead, the gardener can expect some interesting surprises from plants raised from his own seed. Collecting seed is not difficult as long as an early winter does not set in before the seed is ready. The colour of the seed capsule should be carefully watched over a period of six weeks or so when it will change from pale green to a light brown as it dries. The seeds which are flat and black are dispersed when the capsule splits and at this point it should be collected. Fortunately, unless there is a strong wind the dispersal is not immediate and there should be ample time to collect it before it falls to the ground. Place the seed in open paper (not polythene) bags until it has dried and then store, now in sealed bags, in a cool, dry place until March or April. Space sow the sound seed on the surface of a gritty compost and cover with a thin layer of grit of more compost. Gentle heat at this stage will accelerate germination but it is by no means necessary. After germination, which should take place in a month or so, the pot should be kept in a cool greenhouse or fame.

The seedlings can be grown on in their pot and potted up individually in their second year. Alternatively they can be pricked out into small pots as soon as they are large enough to handle and then further potted on as their growth rate allows. Plants from the second method should be big enough to plant out in their second season and are likely to flower in the following year.

Graham Gough is a nurseryman with a growing reputation both for his knowledge and skills with plants. In the second part he considers many of the species, hybrids and cultivars in cultivation in the subject, whether living in Britain or abroad.

Source of article
Growing From Seed - Winter 1990-91 Vol. 5 Number 1
© The Seed Raising Journal from Thompson & Morgan