Ornamental Shrubs

Where would we be without ornamental shrubs to provide colour and mass in a garden? They are among the essential permanent inhabitants that go on, season after season, delighting us with their infinite variety of flowers and foliage, yet demanding little other than an occasional feed and a little pruning to keep them shapely and within bounds. Carefully chosen, they will provide colour and interest throughout the year. I have space here to mention only a few of the many hundreds of shrubs suitable for our purposes, but these will give you some idea of the forms available. The sizes given for the plants are only a rough guide since they vary considerably depending on site, soil, rainfall, and other factors.

Selection

The barberries (Berberis) form an extremely various and useful genus, ranging in height from 500 mm (20 in) to 3 m (10 ft) and thriving almost anywhere so long as the soil does not become waterlogged in winter. They all flower in spring and many follow this with a showy autumn display of berries. B. darwinii, an evergreen, is brilliant in bloom from April, when its clusters of orange flowers open against a background of the tiny, dark-green leaves. It makes a dense bush and can reach a height of 2.5-3 m (8-10 ft) in time, but is easily kept shorter. 8. x rubrostilla, which bears yellow flowers in May, is deciduous and a much smaller shrub at 1m (3-1/4ft); it is noted for its coral-red fruits, among the largest of any barberry, and ruby-tinted foliage.

The graceful arching branches of the ever-green B. x stenophylla, reaching up to 2 m (6-1/2 ft) high, make it particularly attractive, especially when the yellow flowers open in April. More useful in a small plot is a dwarf form of it called ‘Corallina Compacta’, which grows a mere 300 mm (1 ft) high, with flower buds that are coral-red before they open.

A really brilliant autumn show is put on by B. thunbergii, when the bright-red of its berries is joined with the autumn colour of its leaves before they fall. Growing to 1.2 m (4 ft) high, its cultivar ‘Atropurpurea’ has rich copper-purple foliage throughout the summer, while ‘Atropurpurea Nana’ is even more compact at about 600 mm (2 ft) tall. All of these have orange-yellow flowers.

Buddleias are very easy-going shrubs that grow almost anywhere and enjoy plenty of sun. The ones with those long, pointed flower clusters at the end of the new shoots from July to September are cultivars of the deciduous Buddleia davidii. They are available in colours ranging from the very deep violet of ‘Black Knight’ to the pure white of ‘White Cloud’. To get the best flowers, the stems, which grow every year, must be cut back hard in March or April – a treatment that will keep the plant down to a summer height of about 2.5 m (8 ft).

Less common, but most attractive, are B. alternifolia and B. globosa, both of which bear flowers on the previous year’s growth. The weeping buddleia B. alternifolia (deciduous) has slender, arching branches clustered with scented, lavender-coloured flowers in June. It is most spectacular when trained as a weeping tree about 2.5 m (8 ft) tall with an upright main stem. B. globosa (semi-evergreen) blooms a little earlier, when it decks itself with ball-shaped, orange-yellow flowers.

The ornamental or flowering quinces, still often called japonica or cydonia, belong to the genus Chaenomeles. These beautiful and easy-to-grow spring-flowering shrubs are set against a wall, more often than not, where they will thrive and flower well even in the shade; but they will grow just as happily in an open border, where they will make bushes 1.2-1.5 m (4-5 ft) high and wide. There is a large number of cultivars with a single or a semi-double bloom of white or shade of pink or red. All are beautiful in flower, one of the brightest being C. x superba ‘Knap Hill Scarlet’; but it is best to visit a nursery to see them in bloom and to pick the colour that most appeals to you.

Two very fine variegated-leaved shrubs are provided by the deciduous dogwood (Cornus alba): in the cultivar ‘Elegantissima’ the variegations are white; in ‘Spaethii’ they are golden. The species is noted for the bright red bark of the young shoots; in the cultivar ‘Sibirica’ they are a brilliant crimson. Both must be pruned hard in the early spring to encourage the growth of young shoots, which have the brightest colouring. This treatment should keep the plants to a size of 1.5 m (5 ft) high and across.

The purple-leaved filbert (Corylus maxima ‘Purpurea’), a deciduous shrub, has large, round, purple leaves all summer. Easy to grow, it can make a very large bush, but is easily kept to about 2.5 m (8 ft) tall and half as much across by cutting out a few of the thickest branches from the base each winter. It is especially attractive in spring, when the pinkish mauve catkins hang from its branches.

Eleagnus PungensWhen you see a bush of the deciduous Cotinis coggygria (syn. Rhus cotinus) covered in its feathery, pink-to-grey flowers during June and July you can readily understand how it acquired the name smoke tree. The foliage is light green, with rounded leaves, and usually colours well in the autumn; the cultivar ‘Royal Purple’ has wine-purple foliage. Given time, smoke trees can make substantial shrubs some 3 m (10 ft) high, so allow them plenty of room.

Some Cotoneasters, also include a wide range of smaller shrubs, both evergreen and deciduous. Their chief attraction is usually an autumn show of berries, while the deciduous species also have lovely autumnal foliage. They vary in form from the completely prostrate Cotoneaster dammeri, which creeps over the ground and is studded with bright red berries in autumn, to C. henryanus, which reaches 3-3.7 m (10-12 ft) high with arching shoots, large evergreen leaves, and crimson berries in winter. One of the best for a small garden is the low-growing fish-bone cotoneaster, C. horizontalis, which regularly carries a huge crop of small red berries, while its tiny leaves redden brilliantly before they fall. Cotoneasters are certainly among the most useful shrubs for autumn, being tolerant of almost all soils and conditions, although they flower and berry less freely in the shade.

Having scented flowers, all the daphnes are welcome, but none is more so than Daphne mezereum (deciduous), whose bare branches are wreathed with purple-red flowers in February before the leaves expand. Making a rather upright bush growing to about 1.2 m (4 ft), it is sometimes short-lived, although it will often seed itself if the birds can be persuaded to leave the scarlet berries alone.

One of the most handsome evergreen shrubs can be had in Elaeagnus pungens ‘Maculata’ (’Aureo-Variegata’), whose pointed, oval, shiny green leaves have centres splashed with gold. Attractive all the year round, it can eventually grow into a bush about 3.7 m (12 ft) high and wide, but it is easily restrained by pruning.

April and May are the months when most brooms (Cytissus) are in their glory and one can forgive them their tendency to a short life span for their exuberance in flower, when they seem to create an explosion of colour. Although most are lime-tolerant, they seem to prefer a deep, free-draining, neutral or slightly acid soil. C. x beanii is a golden-flowered dwarf broom that would be at home in a rock garden, as would the creamy C. x kewensis. Both are spreading but grow no taller than 300 mm (1ft). A little taller growing is the purple broom, C. purpureus ‘Atropurpureus’, though it too is more of a spreader. One of the most spectacular in bloom is C. x praecox, which may in time reach a stature of 2 m (6-1/2 ft) and has cream flowers, or yellow in the case of its cultivar ‘Allgold’. The tall-growing brooms with bright, often two-tone flowers are derived from common broom (C. scopurius) and seem to need an acid soil in order to survive for long. In common with other brooms they need to be clipped over immediately after flowering to keep them compact. Remove most of the soft green shoots, but take care not to cut into the tough old wood.

Anyone fortunate to have a distinctly acid soil can create a heather garden. By using those plants with colourful foliage – some are brilliant yellow, others silver, bronze, or green – it is possible to create a vivid tapestry of colours that change throughout the year as each kind of plant flowers. The winter-flowering ericas, moreover, are tolerant of chalky (alkaline) soil, and Erica carnea (syn. E. herbacea) and its many cultivars seem to flourish almost anywhere, given adequate drainage and a place in the sun. They mostly grow about 230 mm (9 in) high, gradually expanding into a mat that is covered with flowers at various times between December and March. One of the earliest to bloom is E. carnea ‘Winter Beauty’ (’King George’), which opens its deep-pink flowers in December; it is closely followed by ‘Springwood Pink’ and ‘Springwood White’ in January. Much slower-growing than these, ‘Vivellii’ has an added attraction in its bronze-red winter foliage; its carmine flowers appear in February. Others that make an important contribution with leaf colour include ‘Ann Sparkes’, with deep yellow (almost orange) foliage tipped with bronze, and ‘Foxhollow’, a vigorous gold-leaved form.

A most welcome group of deciduous early-spring-flowering shrubs is the forsythias. All of these are glorious in flower, but best of all perhaps is Forsythia x intermedia ‘Lynwood’, whose branches are thickly clustered with broad-petalled, bright yellow flowers in March and April. Although stocky of growth, it can reach a height and width of some 2.5-3 m (8-10 ft), but careful pruning to remove old wood and the more vigorous shoots after flowering is over will keep it to half that size.

Except in mild areas of south-western Eng-land, the 2 m (6-1/2ft) evergreen tassel bush (Garrya elliptica) is best grown against a wall, where its foliage is less likely to be scorched by cold winds. The roundish, wavy leaves are dark green above and silvery beneath. The bush makes a subdued yet charming display in winter as its silvery green catkins gradually develop to drape the tree in January and February. Male plants have the best catkins – usually about 150 mm (6 in) long, although they may be almost double this length in really warm areas.

The Chinese witch-hazel (Hamamelis mollis) is an invaluable winter-flowerer: its delicate, sweet-scented clusters of strap-like, golden yellow blooms are never blighted by the weather and withstand the harshest cold in January and February. Its mid-green, felted leaves turn an attractive yellow in autumn. The plant usually develops slowly into an open, graceful shrub without pruning and, after many years, may reach a height of 2 m (6-1/2ft) and about as much wide. The cultivar ‘Pallida’ bears much paler primrose-yellow flowers that show up better from a distance.

Holly (Ilex) is an invaluable plant that can be grown as a tree, a bush, or a hedge; it can be pruned and clipped to keep it within bounds, and it need never exceed 1.5 m (5 ft) in height and can be kept quite slim. Heavy pruning will prevent it from berrying, but this is not important if you have chosen a cultivar mainly for its attractive foliage. Both the golden and the silver variegated hollies are rewarding to grow, especially for their impact in winter. I. x altaclarensis ‘Golden King’ is one of the best coloured forms, its almost spineless leaves being broad with a yellow margin. The ‘Silver Queen’ cultivar of common holly, I. aquifolium, has foliage broadly margined with white.

lacecap hydrangeaFlowering as they do from July to October, hydrangeas are worthy of a place wherever they can be grown. Their main disadvantage is that most of the many hybrids and cultivars of the common species, Hydrangea macrophylla, flower from buds formed on shoots that grew the year before, and these buds are susceptible to damage by frost. But provided they are not planted in frost hollows or very exposed sites inland, and get enough sun to ripen their shoots, they can be grown far from those seaside and town gardens where they are such a common spectacle. H. macrophylla provides two basic flower forms: the Hortensia group, with large mop-heads made up of mainly sterile florets; and the Lace-cap group, with daintier flower-heads composed of a cluster of small, fertile florets surrounded by a ring of showy sterile ones. The colour of the flowers depends on the acidity or alkalinity of the soil as well as the variety. Those which are blue or purple in really acid soil are pink or red grown on an alkaline (chalky) one, while if the soil is faintly acid or neutral the colour may be neither one thing nor the other. White-flowered cultivars are white whatever the soil, but they tend to become pinkish in the sun as they age. The most reliable Hortensias include dark-blue/light-red ‘Altona’; pale-blue/pink ‘Europa’; deep-blue/deep-pink ‘Hamburg’; violet/vivid-crimson ‘Westfalen’; and white ‘Mme E. Mouilliere’. Those sold as indoor-flowering pot plants are rarely hardy enough to do well out of doors. Two of the best Lacecaps are the vigorous ‘Bluewave’, which is pink on alkaline soil, and the more compact ‘Lonarth White’.

Very different from these, H. paniculata ‘Grandiflora’ flowers on the new shoots, carrying large tapering panicles of white florets, up to 200 mm (8 in) long in August and September, which gradually turn to a pinkish red as they age. It is one of the hardiest hydrangeas, and it should be pruned hard every spring to get the largest blooms. Cultivars of H. macrophylla, however, are best pruned as little as possible, especially in their early years. If it is necessary to thin out the bushes, do the work in spring, taking out a few of the oldest branches by cutting them off close to the ground. Removal of too much wood encourages a flush of soft growth that can be killed by frost. To give extra protection to the buds, leave the old flower heads on the bushes through the winter.

Feeding is much more important than pruning to keep hydrangeas flourishing. Give them a dressing of general fertiliser and a mulch of well-rotted manure or garden compost over their roots every spring. Few shrubs show water shortage more pitifully than hydrangeas, whose leaves and florets quickly wilt under drought stress. The more organic matter in the soil, therefore, the happier these shrubs will be. They demand generous treatment, but then they will produce a display whose beauty and longevity can be matched by few other shrubs.

Hypericum ‘Hidcote’ is deservedly one of the most popular of the St John’s worts, its sunny, golden flowers opening in succession from July until autumn and making a respectable showing even in the shade. It can ultimately develop into a rounded bush some 2 m (6-1/2 ft) high, but it will take many years to reach that size. Semi-evergreen in habit, it is reluctant to shed all its leaves except in a really harsh winter..

imageThe mere mention of lavender is enough to invoke thoughts of cottage gardens, sunshine, and scent. These plants will thrive anywhere as long as they have sun and a well-drained soil. Old English lavender (Lavandula spica) makes a bush some 1m (3-1/4ft) high and wide, but it tends to become straggly. Much better garden plants are its modern cultivars, notably ‘Hidcote’, which grows 450 mm (18 in) high and wide and bears deep-purple flowers in July. (This cultivar, by the way, is sometimes listed as L. nana atropurpurea.) Lavenders do not make new growth from the old wood, so the only way to prune them is to cut back straggly plants hard in March or April or to trim them more lightly immediately after flowering.

Happy in those awkward, shady spots on the north side of a house or under trees, the Oregon grape (Mahonia aquifolium) is a most useful plant. It has evergreen, shiny, holly-like foliage, and its large clusters of bright yellow flowers on the shoot tips in March and April are followed by berries covered with a dark blue-grey bloom. Fairly slow growing, it can reach 1.5 m (5 ft) high and wide, but is easily kept to about half this size by pruning. Somewhat taller growing, M. japonica flowers in January and February, when its strongly scented, pale yellow flowers open on the long trailing spikes at the ends of the branches. Given sufficient shade its evergreen foliage is a dark lustrous green, but if it is grown where it is sunny and soil is dry its leaves become bronzed, growth is much slower, and it loses its luxurious appearance.

In complete contrast is the daisy bush (Olearia x haastii) from New Zealand, which will not survive without free-draining soil and plenty of sun. It is the only Olearia hardy enough to be grown just about anywhere in Britain. Forming a rounded bush some 1.2-2 m (4 – 6-1/2ft) high, it has small, rather oval leaves that are shiny green above and white-felted below. It is smothered in yellow daisy flowers in July and August. If it becomes too straggly it can be cut back in April.

Pernettya mucronata is one of the most attractive of the small, berrying evergreens, but it is also a lime-hater that flourishes only on really acid soil. Usually growing about 1m (3-1/4ft) high, it gradually extends its territory by means of suckers to form a dense thicket. It will grow in quite deep shade but it will not flower or fruit so readily in such a position. The foliage is small, pointed, and dark green, and the heather-like flowers that appear in May and June are white. The large berries can be white or in shades of pink or red to near lilac, colouring up in late summer and autumn and persisting for a long time. The species is unisexual, so male and female plants must be grown together to ensure fruiting.

Many people might mistake a young Jerusalem sage (Phlomis fruticosa) for a border plant rather than a shrub but eventually it develops into a rounded bush about 1m (3V4ft) high and across. Being a member of the sage and lavender family (Labiatae), it is a contender for a place on a sunny bank or at the foot of a sunny wall. Its greyish, furry, evergreen leaves are attractive for most of the year, while the bright yellow flowers crowd in clusters around the stems in July and August – a time when many other shrubs have finished flowering.

Pieris formosa forrestii ‘Wakehurst’ must rank among the 10 most spectacular evergreen flowering shrubs in April and May, when its clusters of scented, creamy, lily-of-the-valley-like flowers contrast with the shiny, dark green old leaves and the bright red new ones. What is more, this young foliage colour is maintained for months as more leaves develop. It is, alas, another shrub that can be grown only in acid soil. Slow growing, its habit is to form a rather upright bush up to 2.5 m (8 ft) tall, although it may have reached little more than half that height by the end of a decade. Where space is extremely restricted but soil conditions are suitable, the more compact form P. formosa ‘Forrest Flame’ could be chosen. Its red foliage colouring is a little less brilliant, but it is said to be hardier and it is only about half the size of ‘Wakehurst’. Both plants, however, appreciate shelter from north and east winds.

For sheer flower power and good, honest value, the shrubby cinquefoils (Potentilla) are difficult to beat. They are tough, grow-anywhere plants that make tidy bushes neatly clothed to the ground, and they flower on and on in the summer. P. ‘Elizabeth’ develops into a dome-shaped bush about 1m (3-1/4 ft) high and wide with light yellow flowers. P. arbuscula ‘Beesii’, at half the size, is a good front-rank plant, with golden blooms and attractive silvery foliage. A little taller at 1.2 m (4 ft) or more and with a tendency to arch, P. fruticosa ‘Katherine Dykes’ is another with pale yellow flowers, and it has deeply lobed leaves. P. f. ‘Tangerine’, on the other hand, reaches no more than 450 mm (18 in) high, yet may spread more than twice as far. Being deciduous, the cinquefoils offer nothing for the winter season, but as most of them flower cheerfully from early June to October they deserve a place in any garden. If their growth is too exuberant they can be cut back drastically in March.

Roses are undoubtedly the most popular of all the flowering shrubs, a fact that is hardly surprising when you consider how easy-going they are and the quantity of blooms they produce even in their first season after planting. The hybrid tea and floribunda roses that offer such a variety of colours to choose from have an added advantage: the heavy pruning meted out to them allows one to site them in front of a spring-flowering shrub in the certain knowledge that after pruning they will not obscure your view of it, yet later will grow up to screen it. There is also a wide range of old species and shrub roses available that develop into distinct bushes without the need for such hard pruning. But for long-term colour you need to select repeat-flowering cultivars, such as the hybrid musk roses, in order to enjoy as long a season of blooms as possible.

Although generally thought of as a culinary herb, the common sage (Salvia officinalis) is a useful plant for a sunny spot; so, too are its cultivars ‘Purpurascens’, with purple leaves, and ‘Tricolor’, which has cream-splashed leaves suffused with pink and purple. Although they get straggly after some years, the plants are easily started afresh from cuttings or by layering.

The golden form of the red-berried elder (Sambucus racemosus ‘Plumosa Aurea’) is one of the finest yellow-foliaged shrubs and makes a superb show with its beautiful, deeply cut, fern-like leaves from spring to autumn. It bears yellowish white flowers in April and May and the berries follow in June and July. Prune it annually in March to keep it bushy and about 1m (6-1/2ft) high and wide. The ‘Aurea-Variegata’ cultivar of the related S. nigra, a more vigorous shrub, has green leaves with yellow margins.

A notable winter flowerer, Viburnum x bodnantense ‘Dawn’, forms an upright bush eventually some 2 m (6-1/2ft) or a little more high. Its clusters of scented pink flowers open on the bare shoot tips from November to March during mild spells and are completely unharmed by sharp frost.

Weigela florida ‘Foliis Purpureis’ is an admirable shrub for a small plot. Making a neat bush about 1.2 m (4 ft) high and wide, it has colourful purple-flushed foliage and its shoots are clustered with pink, bell-shaped blooms in June. Another cultivar, W. florida ‘Variegata’, is one of the very best variegated shrubs, with pale-cream-edged leaves and, again, pink bell-shaped flowers in June. A shade stronger-growing than its purple-leaved counterpart, it can make a bush about 300 mm (1 ft) taller and broader.

Pruning and propagation

Although the amateur gardener is aware of the supreme importance of shrubs as long-term features of the garden, he sometimes hesitates to plant a particular species or cultivar because he fears it may grow too high or spread too far and so ruin the visual balance of a bed or border. In fact, most shrubs can be restricted to about two thirds of their natural size by cutting them back or thinning out the longest branches from time to time. The important thing is to know when to prune, and this depends on where the flowers are carried. If they are borne on shoots that grew the year before or on older wood, the best time for pruning is immediately flowering has finished; on the other hand, plants that bloom on the current year’s growth should not be pruned until winter or very early spring. Although some shrubs need to be rigorously cut back, beware of over-pruning, since this tends to stimulate growth at the expense of flowering. Remember never to cut back into the old wood of brooms and lavender, which are unable to make fresh growths from the old wood.

There is hardly a garden owner who does not take an interest in propagating plants. Most shrubs can be raised from cuttings of one sort or another, but a handy method, especially with lower-growing species, is that of layering. All you need is a shoot or branch that can be bent to the ground. Make a slight cut in the bark 300 mm (1 ft) or so from the end of the branch, bend it into an ‘elbow’ at that point, then peg down and bury that portion, having worked some peat into the soil beforehand. Tie the upright end to a stake and keep the soil moist. Roots eventually form where the bark was cut and the branch can then be severed from the parent and transplanted. Deciduous shrubs should be layered in autumn, evergreens in autumn or spring.

Layering is a slower method than taking cuttings, but it gives a bigger plant. Most layers are ready for transplanting after one season, but there are a few notoriously slow-to-root plants, such as witch-hazel, magnolia, and rhododendrons, that will need at least two years before they are ready to be moved. Any plant that objects to root disturbance, such as clematis and wisteria, should be rooted into pots of soil or compost instead of the open ground.

04. July 2013 by admin
Categories: Plants, Shrubs | Tags: | Comments Off on Ornamental Shrubs

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