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.
Dwarf Apple-trees are "garden toys," and they do not pay. For ourselves, we never would plant them, unless in pots to be grown in an orchard-house. If our ground were so limited that we had no room for Apple-trees, we would certainly plant Gooseberry-bushes, Currants, or Rasps, or other "small" fruit; and if we had room for only one Apple-tree, it would be one that would some day or other come to something. We - that is, everybody - want Apples by the bushel; dwarfs only produce them by the dozen. When ground is so limited that Apples, to be grown at all, must be borne by little bushes, we think it a waste of ground to plant them, and a waste of time to pinch, root-prune, and train them. To this rule there is only one exception; and that is, when there is a greater extent of walls, 5 or 6 feet high, than is wanted for growing Gooseberries and Currants. In that case we think a few dwarf trees might be planted profitably, just because there is little profit, and less beauty, in having bare walls.
Still, many villa-owners have such trees in their possession, and derive a great deal of pleasant occupation pinching, tying, and petting their little trees. The thousands of villa gardens are not cultivated for the sake of profit, but for pleasure; and there is as much pleasure to be derived from cultivating small Apple-trees and gathering in their fruits, as there is in growing Fuchsias, or Pelargoniums, or Chrysanthemums, or other plants which require staking, tying, petting. Having said that such trees do not pay, we have performed one duty : to those who wish to know how best to cultivate them we hasten to perform another.
Apple-trees which, from the first, are intended to be grown as dwarfs, are, or should be, grafted on some of the dwarfer forms of the Paradise. Even this is not enough to prevent Apple "trees" attempting to grow into trees, more especially if they are planted in rich soils. On poor soils they do not grow into large trees sometimes, unless carefully top-dressed and manure-watered. We have only had such trees to deal with twice. In one of the cases they were in a good deep soil, were lifted and sparingly root-pruned every year, and liberally mulched. They were then 6 or 7 feet high, and about 4 in diameter; were well furnished with fruit-spurs; were handsome pyramidal trees, and bore really good fruit freely. In the other case, the trees had had similar treatment, so far as we could ascertain, but the result was very different. The trees were dwarfs - were hide-bound, stinted, and fruitless. The reason seemed to be that, in the one case, the soil was deep and fertile; in the other, thin, gravelly, sterile, and burnt up.
It is also quite possible that the trees were on an inferior kind of Paradise, for some of the varieties are truly "starving" stocks.
A great deal depends on the intelligence brought to bear on the trees. When trees grow lustily and outrun their space, careful lifting and root-pruning is just what will correct this tendency. Then, when a heavy crop of fruit ensues, which may be so great as to stop their growth, heavy mulchings and manurings are absolutely necessary to enable the trees to stand the strain. To mulch and manure-water trees which are growing well, inevitably causes the trees to grow too strongly; and to do this first, and then be obliged to lift and root-prune in order to correct it, is wrong. Often enough, however, the opposite mistake is made. Trees growing very moderately, and producing some fruit, and an abundant promise of more in the shape of blossom-buds, are often lifted and root-pruned, simply because the satisfactory state they are in has been brought about by that process. The consequence is, that the trees are checked just at the very moment when they ought to be strengthened, in view of the prospective crop so liberally promised by the abundant fruit-buds. Beginners ought to learn to distinguish between fruit-buds and buds which will only produce leaves; for when plenty of flower-buds are formed, with only a moderate amount of young shoots, lifting and root-pruning is the greatest mistake that could be made; - well, no - not the greatest mistake; for lifting trees which are covered with flower-buds and nothing else is a greater one, and we have seen even that mistake committed.
When this is the case, a heavy mulching should be given the moment it is seen that growths are not to be formed, and the flower-buds which form at the points of the leading shoots should be picked out, so that the wood-buds at their base may have a chance of breaking into growth, - if they are allowed to develop into Apples, farewell to growth. The fruit should also be thinned, and plenty of liquid manure given during summer. Such treatment will generally enable the trees to make a fair growth. As we have said, the opposite treatment is to be corrected by root-pruning, and this operation may require to be performed annually. Small trees are much more easily managed at the root than large or even medium-sized ones. In good soil, where root-pruning is annually performed, the ball becomes such a mass of roots that lifting may be done so as to cause no perceptible check at all. Such trees generally prove very satisfactory, and scarcely need lifting so long as they continue to bear; but sometimes spring frosts kill the blossoms, and the removal of the natural check to an over-production of wood - a crop of fruit - being removed, away go the trees into basket wood. When this is the case, the roots require checking, in order to induce a return to fruitfulness.
To "hit the happy medium" in all cases, requires a good deal of intelligent forethought, based upon observation and experience, and this can only be acquired among the trees.
In the matters of pruning, pinching, and training, we should say that the directions given for medium trees apply to dwarfs in everything but one, and that one is, that when the dwarfs begin to come near the size at which it is intended to keep them, the annual growth should be cut back nearly their whole length. When they have arrived at this stage, it is a good thing to be occasionally removing old branches as opportunity occurs, and allowing their places to be filled with younger wood. This also applies to medium-sized trees, and indeed to all trees whatever. When any tree ceases to make a certain amount of annual growth, it begins to decline, and sometimes the decline is precipitate. When trees have grown as large as is considered desirable, the annual growth may very often take the form of young branches replacing old ones, with advantage. Old branches often get covered with spurs, which cluster too closely, and so mutually weaken each other. A careful pruner will be always shortening back his spurs as well as his young shoots, and so keeping them thin and close to the main rods.
When they do get long, thinning out and shortening back should be done gradually and intelligently.