In Part I of this article, I gave you an overview of just what the art of espaliering fruit trees comprises. If you haven't read it, and aren't familiar with the concept, please go back and read that article first. In this article, I'll give you an overview of espalier techniques and the rationale for them.
The training of an espalier must be accomplished in a precise manner, and can take from several to many years. This is not a hobby for those who must have instant gratification! But, to paraphrase de Quintinie, the creator of the
Potager du Roi and of espalier techniques as we know them today, it is a means of delaying your gratification so that it may be more intense and of longer duration. That is, a well-trained espalier will live longer, and bear much more fruit in a much smaller space than an untrained tree. Of course, it also becomes a piece of living sculpture, a beautiful testimony to the interaction of gardener and tree.
The purpose of the all-important formative pruning and training (attachment of branches in precise positions to a support so that they grow and become rigid in prescribed forms) is to form a framework--called in French a
charpente--that becomes the skeleton of the tree. This process is different from traditional, natural-form pruning techniques in that the form of the
charpente is much more controlled, to produce any of hundreds of geometrically recognizable shapes and to optimize the sap flow and thus the fructification of the tree.
A basic principle in the formation of the
charpente is that its branches must be solid and of adequate diameter to support the weight of fruit the tree will bear. In espalier forms that are trained against a wall, (see drawing at right) this is less crucial, but only slightly so, as it is always possible that branches may whip free of their support during a storm and tragically break.
In order to achieve a rigid
charpente, the lengthening of the skeletal branches must be slowed so that they grow in girth instead. This is accomplished with appropriate pruning cuts.
Besides needing to be solid, the
charpente must be as perfectly balanced, or distributed through its given pattern in an even, symmetrical manner. This is necessary to assure the balanced flow of sap throughout the tree. Just as more water flows through a larger diameter pipe, more sap flows through a thicker caliper branch.
And just as a bend in the pipe slows the water's flow, so does a bend in the branch.
The more horizontal the angle of the branch, the less sap flows through it. This is one of the primordial principles of tree physiology that is exploited by the skilled trainer of espaliers, because when the flow of sap is braked, the branch produces
fruit--as opposed to vegetative--buds. Fruit buds--as the name implies--produce a blossom (followed by a fruit) whereas vegetative buds produce a woody shoot with leaves.
As you might have deduced, learning to tell the difference between the two is crucial, not only to the art of espalier, but to all fruit tree pruning. In general, a fruit bud is fat and rounded, while a vegetative bud is slender, pointed, and sleek. Close examination of any fruit tree during the dormant season should make the difference obvious.
In France, where the culture of fruit trees is a consuming passion, the morphology of fruit tree buds, different sorts of shoots, and other physical features is recognized and named in exhaustive detail for each variety of fruit. It's astounding to realize what an intimate knowledge a French fruit grower has of his trees' physiology, and he exploits this knowledge to great advantage. Details of all this are beyond the scope of this article, but
if anyone is interested, please write me and I will write another article on just this topic.Unless you can find a tree of your desired variety already started in its training in an espaliered form (extremely rare in the U.S.), you will have to start your espalier literally from the ground up, in the form of a one-year whip. There is no advantage to starting with a larger tree. If at all possible, plant your future espalier in the late autumn. Although classic U.S. literature recommends against fall planting of stone fruits in Zones 6 and northward, even peaches, cherries, and apricots can be successfully fall-planted in the colder regions if care is taken to mulch them thoroughly.
It is by cutting just above an appropriately-placed vegetative bud that you will make the major decisions in the form of your tree's
charpente. More details about this below, but here are a few general guidelines about bud placement. Cutting just above a vegetative bud will force the tree to branch in the direction of said bud.
For instance, to form a the first U for the
charpente of a candelabra form, you would ideally cut just above a pair of more-or-less opposite buds, as in the drawing at left. Since all fruit trees bear the buds in alternate fashion, you can see that by definition, this is impossible to achieve literally. You will have to choose a pair of buds that are as close together as you can find, and headed in opposite directions. While a space of two or three inches between buds can seem enormous on a one-year whip, as the branches they produce gain in girth, this disparity between their placement will become inconsequential.
In making cuts to form a vertical branch, it is important simply to more or less alternate above buds on opposite sides from one year to the next, always training the subsequent shoot to the vertical. However, to develop a shoot which is to be trained obliquely or horizontally, it is vital to choose a bud which is situated on the bottom of or at least laterally on the branch. Branches destined to become
charpientières will be cut back every year to encourage them to increase in caliper, in general to a distance of about 10 inches from the previous year's cut.
The type of major formative pruning cuts discussed so far are made during winter. But also important is what the French call
la taille en vert or "pruning in green." This consists of pinching new vegetative growth from June to July.
Pinching out of thick lateral growth allows maximum lengthening of the
charpientières. Pinch back the laterals to 5 or 6 leaves to encourage them to develop fruit buds and spurs. The drawing at right gives you the idea, showing successive pinches at '1' and '2'.
Just as important as pruning and pinching is training or
palissage the
charpentières in their desired positions. This is done by attaching them to a supporting framework, which may be a lattice of wood or iron rebar, or a system of tightly stretched, heavy gauge wire or airline cable.
Attach branches with a material that won't cut or girdle the bark. Raffia, plastic plant ties, and cloth are all acceptable. Avoid string or wire. One of the most authentic, handsome, and biodegradable ways to train your branches is to use willow prunings. See the article "Prunings into Plant Supports" in this column for details on how to do it.
The greater the angle from the vertical of the desired position of the branch, the more gradually it must be positioned. Obviously, if the branch is to be trained vertically, that's not difficult. But the more oblique the angle, the more the branch will resist its new position,
and--even more crucial--the more its growth will be slowed because of the braking of sap as it approaches the horizontal. A fully horizontal position must be achieved gradually to allow sufficient sap to flow to the branch so that it will grow (see drawing below).
In France, there exist hundreds of espalier forms, but a dozen or less account for most of the espaliered trees you see in ordinary gardens and orchards. (Yes, most orchards in France are espaliered!) Not all forms are suitable for all fruit species or even for all varieties of that species. In Part III of this series, I'll go into more detail on some of the major forms: what they are, how to achieve them, and which fruits are adapted to them. Stay tuned!
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Products of Interest:
Fruit tree pruners
Lorraine extended-reach pruners
'Lorraine' ergonomic bypass pruners
Lorraine all-steel loppers
