Today’s Garden: How it Evolved
HUNDREDS of thousands of years ago, before the Ice Ages virtually obliterated the rich flora of much of northern Europe, plants such as magnolias, giantand weird tree- ferns thrived in what are now the British Isles. In due course, the ice crept slowly back to the north, and by degrees plants that could live in a cooler spread northward from those parts of Europe that had not been frozen. Then, somewhere about 7000 to 5000 B.C., the North Sea gradually found its way through what is now the English Channel and joined up with the Atlantic. The British Isles were cut off from Europe, and continental plants could no longer reach them.
Theof the British Isles are therefore singularly few, consisting only of those that were growing there at the time the sea broke through. Many of these now thrive so vigorously that they are regarded as weeds.
The majority of the plants grown today in the British Isles have been brought from many parts of the world over the centuries, and have been cultivated in the temperate climate and favourable soil that resemble their natural.
One reason why plant life in the British Isles is so lush is that nowhere is the sea very far away. The great mass of water surrounding the land heats up and cools-down slowly thus preventing extreme variations in temperature. On the southern and western coasts, as far as the north of Scotland, ocean currents tend to bring warmed water in the winter, so that there is a long if not very wide band of country where winter frost is seldom of any consequence. The Atlantic weather brings many rain clouds, which break mostly over the mountainous western areas.
On the eastern side there are few mountains. The northerly seas are colder, and the air sweeps over either from the continent or from the west, where it has already deposited much of its moisture. So the east coast is cooler, drier, and, particularly in late summer and autumn, sunnier than the west. Thus it is that European and sun-loving plants grow better in the more fertile eastern counties than in the west.
The climate of the west favours plants that come from rather similar coastal districts, such as the North American Pacific coast, islands like Japan, or mountainous districts such as are found in western China or the Himalayas.
Between the west and east coasts the climate may vary considerably and be very local, and a great deal of study has lately been made of ‘micro-climates’, which may exist even in a small garden.
For example, in one spot a particular plant may be regularly damaged by a May frost, while if it is replanted only a few yards away it will grow unharmed. The configuration of the land may also modify local climate. A cool, open, breezy place seldom suffers the crippling spring night frosts that fall in sheltered hollows, where temperatures may rise much higher during the day.
A knowledge of local climate is, then, the gardener’s first tool. Correctly used, it will enable him to cultivate plants brought from the vast areas of the world that have a similar climate.
The soils of the British Isles range from heavy, rich (often clay) land to light heathland, which is dry and sandy where naturalexists, boggy where it does not. Most of these soils can be made fertile in some degree.
Some soils contain lime and are termed alkaline, while others do not and are called acid. (Between these two extremes are, of course, various near-neutral stages.) These differences have had an important effect on. Camellias, most heathers, certain magnolias and other shrubs and plants that have been introduced, particularly from western China and Japan, and which have been highly developed by nurserymen during the present century, cannot be grown on an alkaline soil. All are splendid for the purpose of naturalizing in the garden with an acid soil. Fortunately, most plants that grow naturally on alkaline soils can also be cultivated reasonably well on acid soils.
Modern gardens are, therefore, divided into two very distinct types — the acid soil garden, where rhododendrons can be grown, and the limestone soil garden, where the rose family and a great many kinds ofare at their best.