Bulbous Plants

A vast range of beautiful, often exotic flowers can be grown from bulbs, corms, tubers, and rhizomes – all forms of underground plant storage organs. Most of them are happy to be moved (or stored) when dormant and when replanted will produce produce flowering plants when their cycle of growth begins again. For this reason, and because so many of them grow readily without trouble, they are some of the best-value plants that you can buy. Even anyone who has never so much as set a plant in the ground before can put most of these in almost any garden with every expectation of a successful show of flowers.

Most people think of bulbs as chiefly spring-flowering plants, but there is hardly a month in the year when one or another of them cannot be found in flower; and this is of particular importance to anyone aiming for colour all the year round. They can be broadly divided into three groups: those that are frost tender and must be lifted and stored under cover each year; a few that can be left out of doors but need a specially warm, well-drained site such as is found at the foot of a wall; and the vast majority that can be left undisturbed after they are planted, as long as they continue to flourish and flower well.

Apart from certain preferences as to site or soil, there are two important points to re-member about these plants. The first is not to plant them too deep: covering them with a depth of soil equal to twice the diameter of the bulb or corm is generally enough, al-though you can go a little deeper on sandy soil. The second point is that their foliage re- must be left intact all the time it is green in order to feed and plump up the storage organ for the following season; unattractive though they may look, the leaves must not be moved until they have withered.


DoronicumDaffodils and narcissi (both of the genus Narcissus) are justifiably among the most popular of springtime bulbs. Happy in almost any soil, they thrive in most gardens, the clumps increasing in size over the years. A browse through a bulb merchant’s catalogue reveals a tremendous variety of flower shapes and colours to choose from.

Hardly less popular are the gay tulips (Tulipa), with an even greater range of shapes and colours. Although still largely thought of as May-flowering plants, there are tulips that flower much earlier. The hybrids and varieties derived from T. fosteriana, for instance, bloom in early April. The water-lily tulip, T. kaufmanniana, together with its brilliant cultivars and hybrids, as well as the early double and early single tulips, also flower in April.

Most people are familiar with the large Dutch crocuses, whose blooms, striped with white, purple, gold, and mauve, open wide in the spring sunshine. Equally easy to grow and colourful are the winter-flowering cro-cuses that open in February. Their flowers are not so large, but each corm can produce six or more. Crocus ancyrensis, also called ‘Golden Bunch’, is one of the earliest. It is quickly followed by the C. chrysanthus hybrids and cultivars, which offer a wide choice of colours, including blue; many of the flowers have petals beautifully marked or feathered on the outside with a contrasting colour. All crocuses need well-drained soil: if you plant them in clay that lies wet in winter their numbers will soon dwindle.

Less commonly seen, although readily available, are autumn crocuses and the meadow saffrons (Colchicum). These are no more difficult to grow, and they flower, depending on the species or cultivar, at some time in late summer or autumn, when their blue-mauve to pink and white flowers make a delightful addition to garden colour. The colchicums are rather strange in that their crocus-like flowers push up through the bare soil some time after the leaves, which appear in the spring, have died down.

A somewhat similar plant, Sternbergia lutea, also has large, yellow, crocus-like flowers in the autumn, but it is likely to settle down only in a sunny spot where the soil is light or has had plenty of coarse sand mixed into it, and where the drainage is very sharp, such as on a bank. It is also a plant that resents disturbance, so once the bulbs have been planted – 125 mm (5 in) is the correct depth -they are best left alone as long as they continue to flower well.

Those harbingers of spring, the snow drops (Galanthus), are among the first bulbs to flower in the year, some appearing during January in southern gardens. The common snowdrop (G. nivalis) has several variants, one of the best being ‘S.Arnott’, a vigorous cultivar with perfectly formed flowers. Somewhat later, G. ikariae latifolius blooms in February and March and has very broad leaves. Most snowdrops flourish in a semi-shady spot, but G. elwesii – a large, January-flowering species listed in most bulb catalogues -and the October-flowering reginae-olgae, a subspecies of G. nivalis, should be planted in full sun. Although usually bought as dry bulbs, snowdrops are best split up and planted while still in full leaf immediately after flowering. There are a few specialist firms who offer snowdrops ‘in the green’, as this is called, and it is to them you must go for the more unusual species and cultivars.

Far less commonly seen, but equally spectacular, is the winter aconite (Eranthus hyemalis). Its yellow flowers, each rather like a king-sized buttercup backed by a green ruff, open in January and February. The leaves follow the flowers, but die down in early summer, and the plants then lie dormant until the following winter. They are ideal for planting under deciduous shrubs and trees where the soil is densely shaded in summer but gets winter sunshine. What you buy are the underground tubers, and these should be buried in a tray of damp peat for a few days to plump them up before planting them outdoors at a depth of 25mm (1 in).

Pulmonaria officinalisThe yellow Iris danfordiae and blue I. histrioides are two dwarf bulbous irises that help brighten the garden in February; although their stems are short the flowers may be 75 mm (3 in) or even more in diameter. These are joined before the month is out by the purple-flowered I. reticulata, which has rather daintier blooms. You can buy cultivars of I. reticulata with flowers in various shades of blue, mauve, and purple, all of which bloom at a height of 150 mm (6 in), although they are generally a week or so later in coming into flower than the type species.

In March the range expands as the glory-of-the-snow (Chionodoxa luciliae) opens its white-centred blue flowers. The Grecian windflower (Anemone blanda), which offers a choice of red as well as blue and white in its upward-looking daisy flowers, also begins to bloom then. So, too, does the Siberian squill (Scilla sibirica), with its dainty 100 mm (4 in) spikes of vivid, deep-blue flowers, and also its delphinium-blue cultivar, ‘Spring Beauty’, which grows almost twice as tall. Both carry their display well into April. The Spanish squill (S. campanulata) reaches its glory only in May; its spikes of bell-shaped flowers are larger versions of the English bluebell (S. nutans), but they can be had in white and pink forms as well as in blue, and are about 300 mm (1ft) tall.

April and May is the time for the easy-to-grow grape hyacinths (Muscari), with buds tightly clustered in a long, slim cone at the top of each stem. Most of them are blue and reach a height of 150-200 mm (6-8 in), although there is one white form (M. botryoides album) that is also easy to get. The common grape hyacinth is Muscari armeniacum, but there is now a form of it called ‘Blue Spike’ with double flowers that form a much thicker spike when they open.

Almost all these small winter- and spring-flowering bulbs are quite cheap and look best if they are planted in large clumps or drifts, when they can make a valuable contribution to the garden display. If planted apart in ones and twos their impact is lost. You will also find that many of them multiply readily in any well-drained soil to produce more and more flowers as the seasons pass.

Possibly the most stately of all bulbous flowers is the crown imperial (Fritillaria imperialis). Its large, hanging bell flowers are clustered around the top of a stout stalk some 600-900 mm (2-3 ft) high and surmounted with a tuft of green leaves. There is a number of cultivars with flowers in shades of bronze-red to orange, and also a particularly striking yellow form, ‘Lutea’. The bulbs are very large and need to be planted 150-200 mm (6-8 in) deep and 300mm (1ft) apart in rich soil, where they can be left to develop. The flowering time is April and May, when they make a really spectacular display. But beautiful though they are, do not try to smell the flowers: the scent of many cultivars is distinctly unpleasant.

The summer snowflake (Leucojum aestivum) is rather like a giant snowdrop, except that the flower segments are all equal in size. Growing some 450 mm (18 in) high, the stems arch gracefully to display the green-tipped white bells in May. This plant is appreciative of a moist soil and some shade, which also helps show the blooms to best advantage.

Onions, leeks, and garlic all belong to a large genus of plants called Allium, which also includes a number of ornamental flowering plants that are easily grown from bulbs, given a sunny site and reasonably well-drained soil. One of the tallest is A. giganteum, with stout, hollow stems reaching 1.2 m (4 ft) high. The tiny violet-coloured flowers are tightly massed together to make a pompon about 100 mm (4 in) across in July. It is best sited on the sunny side of a plant that can hide most of the stem from view. A. aflatunense is another tall-growing species with rather looser heads of flowers that bloom in late May. Among the brightest-coloured alliums are the yellow A. moly, 250mm (10in) tall; the white A. neapolitanum, 600mm (2ft) tall; and the pink A. oreophilum (syn. A. ostrowskianum) at only 150mm (6in) high. All three have much looser clusters of flowers and bloom in May or June.

Most spectacular of all the hardy alliums is A. albopilosum, its great heads being some 250 mm (10 in) across and made up of large, star-shaped, violet-coloured flowers with a metallic sheen that glints in the June sun. Its height varies between 300 mm (1ft) and 600 mm (2 ft). A drawback of all the earlier flowering alliums is that they also die down early, and once the dried seed heads (which flower-arrangers find useful) and withered leaves are removed, not only is there nothing to mark their position, but you can be left with a gap at an awkward time of year if they are planted in a prominent place.

cyclamen hederifoliumSome of the most dainty and charming flowers are provided by the hardy miniature cyclamens. Their flowers are rosy-red to cyclamen-pink or white and are held 100-150 mm (4-6 in) above the ground; although small, they can be so abundant that there is no chance of them being overlooked. Provided you satisfy their simple needs of good drainage, adequate moisture, and some shade, they will proliferate by seeding themselves. Ideal sites are between shrubs, under trees, and at the foot of a north-facing wall. There are a number of species and forms that flower at different seasons. One of the best autumn-flowering ones is the ivy-leaved cyclamen, Cyclamen hederifolium (syn. C. neapolitanum), which carries its pink flowers from August well into October. These are followed by very ornamental silver-variegated leaves, no two of which seem to be identical in shape or markings. Of the winter flowerers, C. coum (often sold as C. orbiculatum or C. ibericum), whose colour can vary from pink to almost crimson, and which also has highly ornamental foliage, is a delight in February and March.

Whenever possible buy your cyclamens as plants growing in pots rather than as dried tubers, which can be difficult to start into growth. If you do start with dried tubers, make sure you plant them right-side up and do not cover them with more than 40 mm (1-1/2in) of soil.

Summer is the time when those aristocrats of the garden, the lilies, open their beautiful flowers. Some of them are distinctly fussy about the type of soil and situation in which they will thrive, but many of the modern hybrids, such as the mid-Century group, are perfectly happy in ordinary garden soil as long as it is laced with peat and they are well fed. Most come within the 1-1.5 m (3-5 ft) height range. Usually lilies need to be planted 100-150 mm (4-6 in) deep, and the bulbs surrounded with sharp sand to ensure good drainage, while those that send out roots from their stem bases should be mulched thickly each year with garden compost or peat in summer. An exception to deep planting is the June-flowering madonna lily (Lilium candidum); this often grows with its bulb tips just protruding through the soil and should never be planted more than 25 mm (1 in) below the surface.

The sword lilies (Gladiolus) also make an eye-catching show in summer when their spikes of trumpet flowers open. Set the corms about 100 mm (4 in) deep and surround them with sharp sand, planting them from March to May for a succession of flowers throughout the summer. Remove the old spikes as soon as they fade by cutting through the stems just above the fan of foliage; this will encourage the development of secondary spikes. The new corms are best lifted and stored in a dry, frost-proof place for the winter. The tiny cormlets, about the size of small peas, which are often produced in abundance around the new corm, can be grown on to flowering size in a season or two and provide a ready means of increase.

Late summer and autumn is the time when the tuberous-rooted dahlias are in their full glory. The range runs from miniatures to giants with flowers 300 mm (1ft) or more across on stems 1.5-2 m (5-6 ft) high, while flower shapes can vary from neat ball-shaped pompons to the cactus types whose petals are thin and pointed. The colour range is vast, providing almost every shade except blue, and new cultivars are introduced every year. For garden decoration I find the small and medium-sized varieties are best, giving plenty of colour without entailing a lot of work in staking; the dwarf bedding cultivars need no staking at all.

Dahlias can be obtained either as growing plants or as dormant tubers in spring. As they are not hardy the plants cannot be set out until danger of frosts has passed. The tubers can be started into growth in pots of soil under glass or planted out directly into the soil in May. They do well in soil enriched with garden compost or, preferably, manure. Any that grow more than 450 mm (18 in) tall must be supported by inserting three or four stout canes or stakes around each plant and surrounding it with string as it develops. Regular spraying to control greenfly, capsid bugs, and earwigs is necessary to prevent damage to shoots and flowers.

After the foliage has been blackened by frost in autumn the woody stems should be cut down close to the soil and the tubers lifted, dried, cleaned, and stored for the winter. Dividing up the tubers is an easy way to increase your stock of plants, but each tuber should have a small section of the old stem attached to it because the new shoots form only at the point where the tubers and old stem are joined.

nerine bowdeniiSeptember is the month when the flower umbels of Nerine bowdenii, 100-150 mm (4-6 in) across and bearing up to eight of the glistening pink trumpets, begin to open; they may carry on the display into December. Not fully hardy, the bulbs are best planted in a warm, sheltered spot, such as at the base of a south- or west-facing wall. Once established they should be left alone as long as they continue to multiply and flower well. Their strap-like foliage develops in spring and dies down in autumn, when the 450 mm (18 in) flowering stems appear. A group of nerines in flower can be a delightful sight, and it is well worth taking the trouble to find a place that suits them.

Also in flower in October and November are the bright scarlet kaffir lilies (Schizostylis coccinea). Their rhizomes are not too hardy and will be better for having the extra protection of a layer of straw or bracken over them during the winter. They make dainty flower spikes some 600 mm (2 ft) or more high and are not unlike small gladioli. There is a number of old cultivatars with red or pink flowers, but two modern ones seem to be much stronger. They are S. coccinea ‘Major’, with large red blooms, and the pink-flowering ‘November Cheer’. The plants increase by means of the rhizomes and are usually sold by nurserymen rather than bulb merchants.

kaffir lilyFinally we come to the winter-flowering Algerian iris (I. unguicularis, syn. I. stylosa), another whose rhizomes one gets from nurserymen. This iris is hardy but, coming at any time from December to March, the exceedingly beautiful, frail, lavender-blue flowers need protection from frost. The best place for the plants is at the foot of a sunny wall, not only for the protection such a site affords but because the plants need to be kept on short commons to make them flower well. In fact it pays to grow them on what is largely a bed of rubble. Try to find, if you can, the cultivar known as ‘Mrs Barnard’: it has bigger blooms, and produces them more freely, than the type species.

There is no doubt that bulbous plants make a most valuable contribution to colour in the garden at every season of the year, and the majority of them are extremely reliable. But my selection by no means exhausts their potential, as the study of those fascinating spring and autumn catalogues of specialist bulb firms will bear out. Indeed, if you were restricted to the flowers of this group of plants alone, your garden could still be colourful at almost any time.

04. July 2013 by admin
Categories: Bulbs and Corms, Plants | Tags: | Comments Off on Bulbous Plants


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