In the home of dwarf tree culture, that is, in Europe, trained trees are extensively grown upon walls. The gardeners utilize for this purpose not only the walls of stables and outbuildings, and of the enclosed gardens, but long ranges of brick are built for the special and exclusive purpose of accommodating fruit trees. In southern Germany, in Switzerland, in Belgium, in France, and especially in the neighborhood of Paris, there are hundreds of miles of these walls. The walls may run north and south or east and west. Both sides of the walls are used, even when one side faces the north. Currants and gooseberries are expected to thrive on north walls. West walls are considered especially favorable for pears and plums. The walls are nearly always built of brick. They should have a height of ten to fourteen feet. Each wall usually has a coping at the top with a projection of ten to eighteen inches, which sheds the rain, protecting both the wall and the fruit trees. Where extreme pains are spent on the culture of fancy table fruits there are curtains hung from rods along the outer edge of these copings, and the curtains are drawn to protect ripening fruit from too hot sunshine, or to protect the blossoms in the spring season from late frosts.
Brick walls, with all their appurtenances, are less important in America than in Europe and the advantages to be expected from this particular method of culture are decidedly less. Walls would more probably be useful for peaches and nectarines in northern latitudes than for any other fruits.
Cordons and espaliers require some sort of support, however, and where walls are not used trellises are necessary. These may be of wood or wire. There is a belief current that the wooden trellises are better because they reflect less heat, but wire is so much cheaper and more durable that it will usually be chosen.
Five or six wires are needed to make a good trellis for upright cordons. These should be placed twelve to fourteen inches apart, with the lowest wire thirty inches from the ground. All wires should be tight, and to this end stout, well-set posts are necessary. The wires should be loosened in the autumn, before freezing weather begins, and should be tightened again in the spring.
FIG. 23—FRUIT GARDENING AND LANDSCAPE GARDENING COMBINED
From Lucas' Handbuch des Obstbaues
The entire planting, exclusive of the borders, is made up of fruit trees and bushes. Dimensions, 752 × 1,362 feet.
For espaliers the woven wire fences are better. In fact, the woven wire fencing is excellent for all sorts of fruit trellises. Poultry netting makes a cheap and convenient trellis, but it is neither so strong nor so durable as the better grades of woven wire fencing. On the whole it is very poor economy to buy a cheap trellis or to put it up on poor posts.