Trees and shrubs can be trained to specific shapes. We treat these trained plants as their own growth type even if it is an artificial one. Espaliered trees are forced from a "3D" shape to a "2D" shape by pruning and tying them in specific ways. Almost all pluriannual and woody shrubs as well as all fruit trees can be be trained to specific geometric forms. The tying and pruning techniques are different for every species.
Fruit trees are especially interesting in façade greening, as they will benefit from the facade microclimate and bear sweeter and earlier fruits, grapevines, also have a tradition in Europe as espaliered and formed plants, as well as firethorn, wintercreeper and cotoneaster.
A trellis for an espaliered tree can be built from wire rope, metal rods or wood lattices. Generally each trunk or branch section is supported by a trellis wire or lattice, but the supporting trellis elements can also be placed diagonally or horizontally to the trunk and branches. The shoots are tied to the trellis section or just positioned behing the trellis.
Suitable trellises can have only vertical lines, only horizontal lines or can have a grid shape with one dominating direction. (Wich means that in one direction the lattices will be further apart than in the other direction, as in a fence where the verticals are close and the horizontals far apart). The spacing of the main axis should be between 20 and 50 cm.
The growing trunk and branches will apply a strong lateral pressure on the trellis, along with the weight of leaves and fruit. This is important especially for wire rope trellises. Especially with trees that are not planted in their final shape but are trained on the facade, its important that the main branches and trunk align with the anchor points of the trellis, so that weight and pressure are optimally distributed.
The wire trellises with square grids should be modified so that one axis is more dominant.
"Sometimes suitable" wire rope trellises have meshes that are too close or too far apart, or are too tall or too low for the tree.
"Not suitable" wire rope trellises are too small, too tall or too narrow for the selected plant. When the trellis and the shape given to the plant have aren't suited to one another, or when the trellis has only one axis it shouldn't be used for a espalier tree. Some trellises have a grid that is too narrow and too expensive for its intended purpose (5050).