This section is from the book "The Gardener V1", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
It has often appeared to me that the common mode of training fruit-trees against walls might well be modified with great and beneficial advantages. In advancing such a statement, many will be ready to ask upon what grounds I put forward such an opinion, and what fault there is to be found with the common mode of training fruit-trees. The two most common ways of training fruit-trees are the fan - which many think is the most natural, and the best way to properly develop the capabilities and bring into full play all the different parts and resources of the tree.
The other is the upright central stem from the root, and having horizontal branches leading off at right angles from the upright stem, and as far as possible leading off at regular distances apart from the bottom to the top of the wall. I am well aware that there are many excellent examples of both these modes of training to be seen where gardening is carried on with skill and spirit in different parts of the country, and many of them look well when the trees have furnished the wall; but what a long time many of them take before they do so. I know some gardens where the wall-trees are planted from 10 to 15 yards apart (and some at greater distances), and the wall fairly furnished. Well, but what a length of time it took to grow pear-trees to such an extent, and what an amount of care had to be bestowed upon them, even before they could attain to such dimensions; and when anything injurious to either the main stem or roots of the tree attacks one such large tree so as to cause its death, what a blank is caused.
What I am about to state is not with any view to supersede the above modes of training entirely, but more with a desire to remind the readers of the 'Gardener ' that there is often a great waste of time as well as of fruit while waiting the growing of trees trained in either of the above modes. Most people after planting choice fruit-trees become anxious to taste fruit from them, as soon as such can be had, having due regard to health and the growing condition of the trees, rather than keep on growing and training them for the next generation. What I would suggest for consideration to those who may have an opportunity to put such into practice, is this - where any new gardens are in contemplation, let the garden-walls be built to a good height, as no good, but positive injury, results from walls being low, for other reasons as well as a means to allow the trees planted against them to more fully develop themselves to near their natural extent. It certainly is a very great mistake wherever this is not kept in mind.
Supposing a good Pear-tree, when growing upon a good sound and healthy stock, would grow when planted as a standard to 24 feet high and some 10 to 18 feet diameter; but supposing the position in which it is planted will not allow of the tree growing to half these dimensions, and then whenever this is the case, unless those who may have the care and management of the trees well understand what they recpiire, so that the roots and top management are made to work, as it were, hand in hand, the results are rarely satisfactory. What we mean by root and top action often not working well together, may be seen where the walls are low, and the soil of a good healthy and productive nature; in all such cases, unless the manager is well versed in root management, there will in all probability be a great inclination in the trees to produce breast wood all over, and cutting in with the knife (if this is all that is done) seldom brings the desired result; less breast wood and more fruit-buds is what is desired, but with low walls and a strong soil, how is this desired end to be obtained? Not so much by continually using the knife, as by attending to the condition of the roots, either by lifting the tree entirely and cutting away all strong bare roots, or, as we have sometimes done, lift only one half of the roots and replant them into some fresh and healthy loamy soil, and if possible let it be from pasture land, where it has been many years under grass; this may be the safest course to adopt with large trees that may never have had any root-pruning; but when this is done to young trees and before they have attained to much size, and their roots have not wandered far, the whole of the roots can be lifted with perfect safety.
I have seen a lot of pyramidal Pear-trees that had been subjected to a regular lifting every second year, for a number of years; under such treatment they required scarcely any pruning, and their roots became quite a picture of small and healthy feeders. Of course those that did not incline to grow useless wood were not lifted so frequently as those which continued to do so. When all the ground is well loosened and not a mere hole like a flower-pot, they do not suffer to any great degree from lifting, especially if any short half-rotten straw or long dung is put over their roots in hot weather, thus keeping the soil more uniformly moist, and encouraging the roots to keep near the surface, and of course to derive more benefit from the action of the air than when they are allowed to descend deep into the soil. This should be avoided as far as possible.