Broad-Leaved Trees

Trees have a major part to play in any garden by giving height and screening power as well as conferring an air of maturity and permanence. They are also, of course, beautiful in all their varied shapes and sizes. All too often, however, the unwary gardener plants a tree that holds a particular attraction for him or her, without considering its ultimate size. I have lost count of the number of suburban gardens I have seen that are filled to overflowing with a huge, pink-flowering ornamental cherry. There are, in fact, rather few common trees whose growth rate and size at maturity make them suitable for planting in the small garden. Those recommended here are either of naturally modest size or grow slowly enough to remain attractive for many years before becoming too large for the average plot.

There is no way in which you can keep a naturally large, quick-growing tree to a small size when it is planted in a garden. It is possible to have it lopped or pollarded from time to time to reduce the height and spread of the branches, but this cannot be done without ruining the natural appearance of the tree, and there are quite enough hideous examples to be seen in our streets and churchyards already. Far better is to regard larger-growing trees rather in the light of temporary plants. One can then have the enjoyment of a wide variety of specimens for 10, 20, or even more years before they will have to be removed to make way for something new.

One important point to consider when siting any tree that may reach a considerable size is that its roots can extend far through the soil. For this reason it should never be planted close to drains or where the roots could undermine the foundations of buildings. It is not that tree roots physically attack drains and foundations, but they can invade and block a drain if it is defective, and they can absorb moisture from the earth beneath foundations, which may cause the soil to shrink, the foundation to subside, and a wall to crack.

The rate at which trees grow varies enormously and depends not only on the species and cultivar but also on the richness and type of soil and the average annual rainfall. Where I have suggested a size it is an indication of what you might expect after about 15 years of growth. By this time the tree will have passed through its early years, when growth is made quickly, and will have settled down, increasing only slowly as the seasons pass.

Selection

acerThere are about 200 species of maple (Acer), all deciduous, and many of them produce glorious foliage colours in the autumn. Among the finest garden trees are the species native to Japan and China. Arguably the best 6f all for the smaller garden are the various forms of Japanese maple (A. palmatum), which itself is a graceful, slow-growing tree that attains a height of about 4.5m (15ft). It needs a naturally moist, well-drained soil and should be protected from cold north and east winds, which tend to frizzle up the new growth in spring. It is difficult to make a choice between the many attractive cultivars. With coppery crimson leaves throughout summer and the vigour to develop quickly into a shapely, fairly upright tree of about 2.5 m (8 ft), A. palmatum ‘Atropurpureum’ is probably the most commonly planted one. But for contrast in a group, A.p. ‘Dissectum’, which grows perhaps half as high, and its even smaller purple-leaved form A.p. ‘Dissectum Atropurpureum’, are more shrubby in habit and rounded in shape. Another group of these elegant maples, A.p. ‘Heptalobum’ in its various forms, develop into spreading trees about 2.1m (7 ft) high and almost as wide, with horizontal branches. A.p. ‘Heptalobum Osakazuki’, an attractive green in summer, later decks itself in fiery scarlet to outshine all the other Japanese maples, al-though each colours vividly in autumn.

I cannot leave this charming group of trees without mentioning A. palmatum ‘Senkaki’, the coral-bark maple. When its leaves yellow and fall in autumn they reveal the conspicuous coral-red bark of the younger wood, and this makes an attractive feature until the following season’s crop of foliage hides it once again. Beauty of bark is also an attraction of the paper-bark maple, A. griseum. Upright growing, with a dense, rounded head, it reaches a height of about 4.5 m (15 ft) and like many maples puts on a good show of fiery autumn colour before its leaves fall. As the old bark flakes and peels away from the trunk and main branches it reveals the shiny new bark like polished mahogany below.

Although you are often likely to find it listed among shrubs, A. japonica ‘Aureum’ is nonetheless a tree, although it takes years to reach a stature that makes this evident. It is a plant suited to the smallest of plots, where it could grow for half a life-time before it gave cause for anxiety on account of its height. A compact grower, it fans its soft-yellow foliage out in elegant tiers as its height increases. It has a special advantage over most yellow-leaved trees in that it keeps its colour from spring until the leaves are tinged with red just before they fall; moreover they remain yellow even when growing in shade, which is fortunate since the delicate foliage can be scorched by very strong sunshine.

The snowy mespilus is one of those plants that has had its botanical name changed many times, so that it appears under a variety of guises in catalogues and on nurserymen’s labels. The one to which I refer is widely known as Amelanchier canadensis, although it may be listed as A. laevis or, more properly, A. lamarckii. It develops into a slender, compact tree about 4.5 m (15 ft) tall and thrives wherever the soil is neither too hot and dry in summer, nor waterlogged in winter. It has two notable displays a year. The first is in April, when its branches are smothered in white blossom; the second is in September, when its leaves colour richly several weeks before they fall.

One of the most beautiful and striking of all coloured-foliaged trees is the yellow form of the Indian bean tree (Catalpa bignonoides ‘Aurea’). Its large leaves are broad and shaped rather like the heart symbol on a playing card. Their soft-yellow colour is held throughout the summer and autumn until they fall – unlike so many golden-leaved plants that take on tones of green as the season advances. It is a slow-growing, spreading tree unlikely to exceed a height of 4.5 m (15 ft) in 15 seasons and it can be kept to about 3.7m (12ft) by light pruning. Even large specimens will shoot freely from old wood if they have to be cut back hard. This is not a tree to plant in a windy site, however, because of the large leaves, which would be blown into tatters, and the fact that the wood is rather brittle. Because of this it is better suited to a town garden than to an exposed country one. It is not fussy about the soil as long as it is well drained, and it prefers a sunny site. But die-back and frost damage can be a problem in areas with very cold and wet winters and springs.

Better known for its berrying shrubs, the Cotoneaster genus also offers garden trees which do well almost anywhere, even on those thin soils overlying chalk and limestone. C. ‘Cornubia’ is one with spreading branches and semi-evergreen leaves. It has perhaps the largest red berries of all and, surprisingly, they hang on the tree for months, making a brave show. Size, however, is its disadvantage since its ultimate 6 m (20 ft) width calls for a fair-sized plot. Where space is limited, the weeping, 3 m (10 ft) ‘Hybridus Pendulus’, trained as a small standard, might be chosen. This one is evergreen, its long, trailing branches being clothed with shiny leaves that contrast well with its abundant scarlet fruits.

While most cotoneasters are known for carrying red berries, those of C. ‘Exburyensis’, another semi-evergreen sometimes available as a standard tree, are creamy yellow. They are carried in clusters and show up even better than red ones, and they often persist until after Christmas.

Hardy and easy-going, doing well even in towns and in seaside locations, the thorns are very adaptable garden trees. Those grown for their blossom are mostly forms of the native white hawthorn or may (Crataegus oxycantha). Co. ‘Plena’ is a double white; Co. ‘Rosea Flore Pleno’ is a double pink; Co. ‘Paul’s Scarlet’ is a double scarlet. All form well-shaped trees of about 4.5 m (15 ft) in height, usually without any particular attention on the part of the gardener, and flower in May.

Several of the hollies (Ilex) are extremely effective for providing year-round colour in a garden. I do not mean the ordinary dark-green kind that is so often stripped of its red berries by the birds long before Christmas, but its relatives with variegated foliage. Their leaves are usually margined with a broad band of yellow or white and look extremely handsome, especially when caught by a ray of winter sunshine. They will attain a height of about 4 m (13 ft) in about 15 years but are quite slow-growing thereafter.

Hollies usually carry male and female flowers on different plants, so you will need to have at least one of each if you want berries. But do not be misled by their names: ‘Golden King’, for instance, is a female cultivar, whereas ‘Golden Queen’ and ‘Silver Queen’ are both male.

In June you will find plenty of laburnums opening their yellow pea-shaped flowers, but most of them seem to be rather indifferent seedlings. To have the best display you need to buy a 3.7m (12 ft) tree of the hybrid cultivar Laburnum x watereri ‘Vossii’. This one bears the longest golden racemes (flower clusters), which sometimes reach a length of 450 mm (18 in), and a tree in full bloom is truly eye-catching. It is essential to plant laburnums in well-drained soil or they are unlikely to survive for long.

Blossoming in April and May, the flowering crab-apples (Mains) match the ornamental cherries with their display, and follow up with a spectacular crop of fruits. Many cul-tivars and varieties are grown, and all are perfectly hardy, moderate in size, and quick to settle into a flowering rhythm. Perhaps the best fruiting one is Mains ‘John Downie’, whose white flowers in May are followed by comparatively large, conical, golden and scarlet crab apples that can be used for making jelly. It forms an open, branching tree some 5.5 m (18 ft) or more tall. M. ‘Golden Hornet’, also white-flowered, is about as tall but has a more upright shape. Its fruits are bright yellow in colour and hang on the branches long after the leaves have fallen. M. ‘Profusion’ is a crab with wine-red flowers and carries a good crop of small crimson fruits in October. It has an added attraction in that the young spring growth is copper coloured at first.

Flowering at about the same time are the Japanese cherries (Prunus). Many of them are lusty growers so you need to select cultivars with care in order to avoid planting trees that will outgrow the space available. All are extremely beautiful in blossom and their shapes vary from spreading to erect. P. ‘Okame’ reaches some 4.5 m (15 ft) high, but is fairly upright growing. Its bright-pink flowers open as early as March in a mild year.

Making a compact pyramid-shaped tree of 3 m (10 ft), P. X ’Pandora’ has soft pink blossom in April. A cultivar suitable for a really small plot is ‘Amanogawa’ which, having reached a height of 4.5 m (15 ft) after many seasons, will still be no wider than about 600 mm (2 ft). It is a charming sight when its semi-double, pale pink flowers open in May. Beautiful though these Japanese cherries are, they all suffer one drawback: birds are liable to peck out their buds in winter. In rural areas, especially where bullfinches are common, you may never see many flowers on a tree unless you spray the branches with a bird-repellent. Strange to say one rarely has bird trouble with the winter-flowering autumn cherry (P. subhirtella ‘Autumnalis’), which bullfinches ignore. This delightful little tree blossoms off and on from November through to April whenever the weather is mild. Although one crop of flowers wreathing its slender stems may be blackened by freezing winds or slashing rain, they are replaced as soon as the weather improves. Obviously its performance can be assisted by giving it a sheltered position, rather than one exposed to the full blast of north and east winds. This form has white semi-double blossom. That of the related cultivar ‘Autumnalis Rosea’ is a charming pink, but can be somewhat variable; it is as well, therefore, to see what colour pink you are getting before buying a tree. The type species and its cultivars are fairly slow growing, eventually making a tree about 3 m (10 ft) high with a somewhat rounded outline if uncut. But in winter there is always the temptation to visit it, armed with a pair of secateurs, to gather some of the budded sprays that will open indoors if stood in water, just as shoots of winter jasmine do.

One of the most colourful of garden trees you could wish for is Robinia pseudoacacia ‘Frisia’. Its leaves are bright yellow in colour, without so much as a trace of green, from spring until they fall in the autumn. Against a dark background or planted in association with a deep-purple-leaved shrub, it can make a spectacular sight. Unfussy as to soil type, it should grow quickly to some 5.5 m (18 ft) as long as the site is well drained.

Happy in most places where there is not a lot of lime or chalk, our native mountain ash (Sorbus aucuparia) is a good garden tree, although a little too vigorous for many plots. It has given rise to many hybrids and cultivars most of which also have good autumn tints and colourful, berry-like fruits. Although their display is not so brilliant, the trees with yellow or white berries seem to be less attractive to birds in some areas and therefore provide a longer display.

Weeping trees, with their downward sweeping branches, have a special charm of their own. They are often an ideal choice for a small plot because many will increase in height only if the central shoot is tied to a vertical stake or cane each year. Once you stop training them upwards they stay at that height. An obvious exception is the ordinary weeping willow (Salix babylonica), which grows ever upwards and outwards as season follows season until it is huge. One of the best of the weeping types is Young’s weeping birch (Betula pendula ‘Youngii’). Another attractive one is the weeping purple beech (Fagus sylvatica ‘Purpurea Pendula’); much slower-growing than its green counterpart, it is unlikely to outgrow its welcome.

Another excellent weeper for a small plot is the willow-leaved pear (Pyrus salicifolia ‘Pendula’). If sited against a dark background to accent its outline and show up the silvery foliage, it makes a delightful picture through-out the spring and summer, especially when it is old enough for its branches to sweep the ground. It can get up to about 3.7 m (12 ft) or so in 15 years, but careful pruning of any upward arching shoots will help restrain its height if necessary.

Maintenance

If properly planted trees are no more difficult to establish in a garden than anything else, but they must be firmly staked. If they are blown about and rocked by the wind, their roots are constantly wrenched and loosened and so never have a chance to establish themselves. The result is at best a sickly tree, at worst a dead one. A really stout stake and an adjustable plastic tree tie may cost almost as much as the tree itself, but are worth it.

The stake must be long enough to reach to just below the ‘head’ of the tree, so that the whole length of the trunk is supported. Failing that, there is always a danger of the stem snapping just above the topmost tie when the tree breaks into growth and the new shoots and leaves provide the wind with greater leverage. Allow also for at least 600 mm (2 ft) of stake to be buried in the ground to ensure that it remains firm. Drive it into position after excavating the planting hole but before planting the tree, so that you do not damage any roots.

Although you can tie trees to their stakes with soft rope (or even with an old nylon stocking, although this is unsightly), a purpose-made plastic tree tie is best. These are equipped with a buffer that fits between the tree and the stake to prevent chafing. The plastic strap has enough give so as not to strangle the tree as its girth increases, and it can be adjusted by means of a buckle to ensure that the tree is held snugly but never too tightly. Whatever else you may use, never tie a tree to a post with the aid of wire, or irretrievable damage may result.

05. July 2013 by admin
Categories: Shrubs, Trees | Tags: , , | Comments Off on Broad-Leaved Trees

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