The range of possible fruits for the garden is great, from the strawberry, a herbaceous plant occupying only a square foot or so of ground, to the apple, pear, plum or cherry, any one of which can produce a large tree 20 ft (6 m) high and as much in diameter. Between these extremes are cane fruits, such as the raspberry, loganberry and blackberry, which can be trained to wires or against fences, and bush fruits, such as the gooseberry and currant, which are shrubby in habit and occupy as much space as a moderate-sized shrub.
There is nothing particularly ornamental about a strawberry, raspberry, gooseberry or black currant, but red and white currants can be quite attractive when in fruit and well-grown apples and pears really add something to the appearance of the garden. Both when in flower and in fruit.
Another point that must be considered is that fruit often requires rather special attention. It is not always easy to fit in fruit with other plants and the idea that a few fruit trees can be planted in the middle of the vegetable garden is likely to result in poor fruit as well as inferior vegetables.
The ideal thing is to keep fruit in a section to itself, but. Where space forbids this, fruit should at least be kept sufficiently separate to enable it to be sprayed, thinned. Pruned, led and picked without interference with other plants nearby.
Propagation and Training
Gooseberries and currants are produced from cuttings which are grown on for two or three years by nurserymen and sold as young bushes of an age for fruiting. Raspberries are grown from suckers produced quite naturally by the plants and these start fruiting in their second year. Strawberries are produced from little plantlets on runners which grow naturally from the mature plants, and will fruit in the summer following planting, but more freely the second year.
All these plants are said to be grown on their own roots. This means that the plant or bush is of the same kind throughout, its roots having been produced by natural processes from its above-ground parts.
Grafted Tree Fruits
This is not so with the tree fruits; apples, pears, plums,cherries, etc. Only very rarely are these on their own roots, and never when purchased in the normal way from nurserymen. This is for two reasons; one is that they are difficult to increase by cuttings or layering, the other is that by grafting them on to a different rootstock very substantial advantages can be gained.
Grafting is an operation whereby a shoot or growth-bud of one plant is joined to the roots of another, which is subsequently prevented from producing any more top growth of its own. A grafted plant is therefore a union of two different, and even dissimilar, plants, one of which, known as the scion, provides all the branches, and the other, known as the stock, provides all the roots.
The two parts, though completely and \ permanently joined together, continue to preserve their own individuality, the scion producing the stems, leaves, flowers and fruit characteristic of it, and the stock its own particular kind of root system. But though the two parts do not intermingle. They do exert an effect upon one another. A given variety of apple, for example, may grow more rapidly and make a bigger tree on one rootstock than upon another, or it may start to fruit at a younger age.
Dwarfing and Vigorous Stocks
A great many rootstocks have been tested and classified forjust these kinds of effect. Those that restrict the growth of trees are known as dwarfing stocks and those that encourage growth are known as vigorous stocks. In-variably the dwarfing stocks encourage early fruiting and as a rule the more vigorous the stock the slower is the tree grafted on it to come into bearing.
All this is obviously of the greatest possible interest to the owner of a small- to medium-sized garden. Fruit trees of restricted size that start to fruit almost at once are likely to be much more suitable than very large fruit trees that may not bear much for eight or ten years.
The Mailing Apple Stocks
There are so many stocks available for apples that they have been given numbers preceded by a letter; M for Mailing, indicating that the stock was selected at the East Mailing Research Station, and MM for Malling-Merton, indicating that it was produced jointly by this station and the John Innes Horticultural Institution. Thus M 2, M 7, M 9, M 16, M 25 and M 26 are all useful apple stocks in the Mailing range and MM 106 and MM 111 are two good apple stocks in the Malling-Merton range. M 9 gives the smallest tree and the earliest fruit but on poor soil or with varieties of naturally weak growth it can be too dwarfing. M 7, M 26, and MM 106 are not quite so restrictive and are probably the three best apple stocks for most gardens. M 2 and MM 111 are fairly vigorous and suitable where sturdy bushes are required. M 25 is the most vigorous of all and very suitable for standard apple trees.
With pears there is not such a wide selection. Quince stocks are commonly used and are fairly dwarfing, that known as Quince C being more dwarfing than Quince B, which in turn is more dwarfing than Quince A. Seedling pear stock grows a much larger tree.
The Single Stem Cordon
It is not necessary for the amateur gardener to become an expert on fruit stocks, for the nurseryman from whom he buys his trees should be able to provide them on stocks suitable for the purpose for which they are required, but the gardener should know that different stocks exist and he should have a general idea of what influence they have on his trees.
By using a dwarfing stock it is possible to restrict a fruit tree to a single stem, no more than 7 or 8 ft (225 to 2-5 m) in length, and still pick worthwhile crops from it. Such trees are known as single stem cordons and they are very useful in the small garden. They can be planted in rows, the cordons as close as 2 ft (60cm) apart with 5 or 6ft (1-5 to 2 m) between the rows. A single row of apple or pear cordons can make a most attractive screen between one section of the garden and another, may be grown against a fence or may border a path.
Another way of training fruit trees is the espalier. This is a French name for a post and wire fence but it is also used for fruit trees trained to grow against such a fence. Each espalier or horizontal-trained tree has a stout central stem from which grow horizontal arms in one plane only. The arms are spaced about 15 in (38 cm) apart and there may be three, four or five tiers of these arms, giving a tree from 4 to 7 ft (1-25 to 2-25 m) in height. Espaliers are usually spaced about 8ft (25m) apart so that, after a few years, their horizontal arms meet and they make a continuous fence or screen. They can be highly decorative but need a little more management than cordons. Espaliers need not be trained against wire fences: they are equally suitable for training against walls.
A third form of trained tree, particularly suitable for walls and fences, is the fan. In this the main branches radiate from one place like the ribs of a fan. It is a form of training that suits plums, cherries, peaches and nectarines better than either the cordon or the espalier form as it allows for a lighter system of pruning, to which these trees respond.
Soil Preparation and Planting
The details of soil preparation and of planting are exactly the same for fruit trees and plants as they are for ornamental trees, shrubs and herbaceous plants. Like them they will occupy the ground for a considerable time, during which it will not be possible to dig or fork the soil deeply, so the initial cultivation should be thorough and the ground clear of weeds at the time of planting.
All the large fruits need secure staking or, if they are grown against walls or fences, secure tying. Autumn and winter are the best times for planting everything except strawberries, which are best planted in late summer but, failing this, they can be planted in early autumn or spring.
It is the pruning of fruit trees that seems most puzzling to the inexperienced and this is not surprising for even the experts differ in the methods they advise. However, it is possible to reduce pruning to quite simple rule-of-thumb methods which will give good results.
Taking the simplest first of all; the cane fruits, a term which includes raspberries, loganberries and blackberries, bear their fruit on one-year-old stems or canes. These canes are produced during the late spring and summer and one lot of young canes will be growing up while the previous lot is fruiting. As soon as the fruit has been gathered, the old canes that have borne the crop are cut right out and the young canes take over. If there are too many of them and from five to seven per root is usually enough – the excess can be cut out at the same time. The ones to retain are the strongest and most conveniently placed for training.
Exception to this general rule must be made for autumn-fruiting raspberries which crop on the current year’s growth. All canes are cut practically to ground level in late winter and the best of the new canes are retained for fruiting, others that would cause overcrowding being cut out at an early stage.
The pruning of black currant is not dissimilar to that of cane fruits for this also bears its fruit best on year-old stems. As soon as the fruit has been picked, or at any time during the autumn or winter, as many as possible of the stems that have borne fruit are cut out, but all the strong young stems are retained. It may not be possible to cut out all the old stems, because some good young stems may be growing from them. The new growth does not all come from the base or from the roots, as it does with raspberries, loganberries and blackberries, so a little common sense is required. The rule should be to get rid of as much as possible of the old without wasting anything good of the new.
Peaches, Nectarines and Morello Cherries
Again there is a similarity between pruning black currants and the pruning of peaches, nectarines and morello cherries. All fruit on year-old stems and the aim is to get rid of the old fruiting stems and replace them with the profitable young ones. Sometimes the trees need a little assistance to make enough young growth to replace the old. This is done, in late spring and early summer, by thinning out the young shoots a little at a time until there are only about three to each fruiting stem: one somewhere near its base, one about half way up, the third at the tip. The last two are left to draw sap up through the stem and help to swell the fruit. It is the shoot near the base that will be retained at pruning time, after fruit has been gathered or in the autumn or winter. The rest of the fruiting stem is then cut out and the young basal shoot trained in its place.
Apples, Pears and Red and White Currants
When we come to look at apples, pears and red and white currants we find a quite different system of bearing fruit. It is not carried on the year-old stems but on older branches and in particular on short side growths from them that are composed almost entirely of fruit buds. They are quite unlike any other shoots, indeed they are not shoots at all in the popular sense but little congested clusters of fat buds. They are called ‘spurs’ and they are very important as the whole object of pruning is to encourage their formation.
A tree left to its own devices will produce spurs freely along the length of stems two years and more old. But a completely un-pruned tree soon becomes such a tangle of growth that it is difficult to do anything with it, even to pick the fruit, and this may be produced in such quantity that individually the fruits tend to be small.
The easiest way to prune apples and pears is simply, in autumn or winter, to thin out the older branches so that the tree does not get overcrowded. Particular attention should be paid to the centre of the tree which should be kept fairly open so that light and air can penetrate and the fruit grower can get in to pick the fruit. If two branches cross and cut off the light one from another, one should be removed. If the trees get too big some of the branches can be cut back. Where possible the cut should be made at a fork so that another smaller branch continues to draw sap up through the stump. This is known as de-horning and may only be necessary ever)’ eight or ten years – perhaps not at all if the trees were grafted on fairly dwarfing stocks. It is trees on vigorous stocks that tend to get out of hand and grow-so tall that it is very difficult to gather fruit from the topmost branches.
This kind of common-sense thinning, and occasional de-horning, is known as regulated pruning. It is suitable for trees grown in more or less natural shapes, as bushes with a head of branches on a short leg or main trunk, or as standards with a head of branches on a taller trunk. It is not suitable for trained trees, such as cordons or espaliers, which must be restricted to a much more formal plan imposed upon them by the gardener.
For these pruning must be done in summer, as this has the effect of depriving the trees of a lot of leaves and so restricting their growth. The work is usually done a little after mid-summer but it is the state of growth rather than the calendar date that really matters. By late spring fruit trees are usually growing fast and they continue to do so for several summer weeks. Then they slow down and the young shoots begin to change colour and texture, becoming browner and harder, particularly near the base. This is the signal to start summer pruning.
The operation itself is quite simple. All the young stems, except those extending the ends of branches, are shortened to a few inches. At the base of each young shoot there is a little cluster of very small leaves; ignore these. Above this basal rosette are the properly developed leaves. The shoot should be cut off just above the fourth or fifth of these leaves. In autumn or winter these summer-pruned shoots should be further shortened to I or 2 in (25 to 5 cm).
The only other pruning that trained apples and pears need is a shortening of the leading stems, that is. Those that are extending the ends of the branches. In a cordon tree only one such leader is needed at the summit of the tree. It is left unpruned until the cordon reaches the maximum desired height, after which it is cut out. In an espalier there will be one leader at the summit and one at the end of each horizontal branch or arm. Each should be shortened to about 15 in (38 cm). Only one new shoot will be required the following spring at the end of each horizontal arm to extend it still further, but three shoots can be retained at the top of the tree; one to go straight upwards and so increase its height and two to be trained to right and left as a further tier of horizontal arms. When all available space is filled, or the espaliers have reached the maximum desired height, all further extension shoots are removed.
Sweet cherries are pruned in a similar way, except that when the shape of large trees is regulated the work is done in late summer or early autumn. This is to lessen danger of infection by a disease known as bacterial canker which is liable to enter through wounds in late autumn or winter.
Bush and standard plum trees are usually regulated, the work being done as soon as the crop has been gathered. When plums are trained, the fan form is usually adopted and summer pruning is applied. But rather earlier than for apples and pears. About mid-summer, or even a week or so before, each young shoot is shortened by a few inches. Plums do not submit so well to really severe pruning and so are seldom grown either as single stem cordons or as espaliers.
Pruning After Planting
The first pruning after transplanting should usually be rather more severe than that which follows. This is essential with all cane fruits which should be cut to within 4 in (10cm) of ground level, and usually also with blackcurrants which should be cut back to about 6 in (15 cm). Weak gooseberry and red currant bushes may be similarly hard pruned but strong bushes can be treated more lightly and permitted to carry some fruit the first year.
Left to their own devices some fruit trees produce more fruit than they can mature to a satisfactory size and therefore the young fruits need to be thinned. This is most likely to occur with cooking apples, which need to be individually large. The thinning is commenced when the fruits are no larger than marbles but it should not be completed until after mid-summer as quite often there is a considerable natural drop of fruit about then. Peaches may also need thinning if they are carrying a big crop and this, too, is done in stages, completion being left until the stones have formed within the fruits, a condition that can be ascertained by cutting a fruit in half.