One of the things that may discourage gardeners from growing some sorts of fruit is the apparently elaborate pruning methods that seem to be involved. Whole books are devoted to this esoteric art and offer many different methods, especially for grapes and pears which seem to have attracted more different and diverse pruning regimes than all other fruits put together. In these complex instructions, that pruning, which is the truly necessary minimum, has become overtly complicated - mostly because of the desire to train fruit trees into constricted forms. Although of course for the finest results then the more care and skill employed the better, but in reality pruning is not so difficult when reduced to the simple basics. Indeed one can get good results with a much less complex methodology than the expert books seem to imply.
We have to prune for many reasons; to remove dead and diseased wood, to let in light and air, to encourage fruiting rather than growth but most of all pruning is done to control size. For most trained forms we must continually prune to create the shape and after a few years to confine the vigour of a tree into a given space. But trees growing in their natural form are almost always best left alone and then look after themselves admirably. So by desiring heavily trained forms we create the need for so much pruning. However unlike trees the soft fruits qualify under almost all of the reasons to prune almost all the time as they soon get congested, diseased and unproductive if left unpruned . On the plus side they are also very forgiving and easy plants to practice on, and it's better to learn on these than to assault trees which will suffer more if subjected to poor pruning.
Raspberries are the simplest case, particularly Autumn fruiting ones, all the old canes and any new ones that have sneaked in are removed at ground level during late winter. In spring the new shoots coming from the ground are thinned to leave only the strongest to flower and fruit, these are then pruned away in their turn the following winter. No canes survive longer than a year so most pests and diseases are removed with the prunings. The stool, as the root and bud system is called, can be productive for decades providing the plants do not get virus diseases, the hard pruning helps prevent these but even so raspberry plants rarely outlive ten or fifteen years productively.
Summer raspberries are similar but their canes do not fruit the same year but wait out the winter. During the next year sideshoots grow from the old canes and carry the fruit then the whole cane withers and dies. Meanwhile new canes spring from the ground underneath; these need to be thinned early on to save removing too many of them, with the old, at the later pruning when they would have grown large and wasted the plant's energies. As soon as all the old canes have finished fruiting they are cut away at the base to leave the remaining new canes room to ripen well. It pays to thin these out, and to tie them down to strong horizontal wires to get a good burst of fruiting sideshoots in the spring. Canes therefore cannot be older than two years old when they are pruned out after fruiting so pests and diseases find it hard to build up.
All the brambles and berries that are related to raspberries are treated exactly the same way except they have much longer canes and need more and stronger wires for support. Their longer canes mean the new ones need temporary tying in place during summer before the old are removed to make space for them. (As I'm sure you are all well aware they also mostly have vicious thorns which makes their training a slow and/or painful affair.) The true brambles occasionally fruit a second or third time from the old canes but not so productively and they are rarely worth retaining.
For most other shrubby fruiting plants we can use similar pruning methods; we choose the best wood for fruiting and remove the other as soon as possible to prevent it wasting resources. Raspberries and their kin are easy as all the canes come from the ground, and most of them wither after fruiting, so it is not difficult to decide which wood must stay and which go. With other plants the choice seems more complicated but is much the same.
So black currants for instance are like raspberries, planted deep they throw up new canes which grow one year to fruit the next. But black currants are different in that their canes do not wither after fruiting but stay alive and form sideshoots that fruit productively the next year so these can be retained to fruit another year, and so on. Unfortunately all the new growth then tends to come on the ends of the ends of old canes and the plants get bigger and bigger. So to rectify this they are pruned much like raspberries but not quite so severely, one third of all the old canes, with regrettably lots of young wood on it, is cut away to ground level after fruiting. This leaves a clear space for young canes to grow into and fruit before they are removed in their turn. (As with raspberries it is worthwhile thinning the new basal shoots during spring so only a few strong canes are allowed to form.) As no wood can be more than three years old then many pests and diseases are removed with the prunings which does help keep big bud and reversion off the plants, but even so the stools deteriorate after a decade or so. (Theoretically it would be possible to grow black currants as cordons or espaliers but this is rarely done.)
Red and White Currants and Gooseberries do not fruit on young shoots coming from the ground but do fruit well on sideshoots that come from older wood. The flowers and fruit come directly from buds that are on wood that grew the previous year. So instead of doing the thinning and pruning to ground level the shoots are cut back to stubs which are growing from out of old wood canes that form a semi-permanent framework. Each winter almost all shoots are pruned back to one or two buds growth of that year forming little stubs on the old wood called spurs. In spring almost all the young shoots come from these stubs or spurs left on the framework, those coming from the ground are totally removed and almost all the others are pruned back by two thirds in length soon after midsummer. The only shoots that are not pruned so hard are those called leaders; those growing in the right direction to be allowed to extend the framework, these are usually tipped in winter to promote more sideshoots. Because the old wood is retained with it's burden of spurs then it can take almost any shape; cordons, espaliers and gridiron shapes can all be easily wrought from these plants. There is some advantage to having cordons as then many more varieties can be squeezed into the same site and espaliers are particularly suited to growing on walls or fences especially where space is limited. As the old wood does remain for years it can build up pests and diseases and although it is possible to replace worn out bits of the framework with newer younger limbs the life of the whole plant may be too short to justify it. I find that despite all care gooseberries do not often outlast fifteen years or red currants twenty.
Grape vines are not unlike red currants, they fruit on sideshoots formed on wood that grew last year. But whereas the currants flower and fruit directly from buds made the previous year with grapes the flowers appear about three to five leaves out on the young shoots, counting from where their buds started on the year old wood. Thus they have to make quite long shoots before the flowers appear so they come much later than other fruits usually not blooming outdoors till July. Grape vines make so much vigorous growth from every adventitious bud that summer pruning is essential if you are not to get swamped by the vines, though they do not send many up from the ground. All shoots springing from anywhere other than last year's wood and all the non-flower bearing shoots are rubbed off as soon as they can be discerned. The fruit bearing canes are best left unstopped and again any leaders required to fill or extend the frame are left untouched in the summer. In winter all the young growths except the leaders are cut back to stubs of two or three buds thus creating spurs. The leaders may then be tipped or shortened to increase their tendency to make sideshoots.
There are however a couple of points that make grapevines different. First, given the opportunity they make huge frameworks, these are no problem providing that most of the fruiting wood is at approximately the same height and none is allowed to rise far above the rest. If any wood is higher than the rest it will steal all the sap and buds lower down will not break. The second difference is that unless the number of bunches is reduced the vine will over crop; failing to ripen many of the bunches and progressively doing badly year after year. Whereas most soft fruits do not carry excess fruit in this manner and so need no thinning, grapes must have the bunches reduced in number depending on the age and vigour of the vine. The fewer bunches left then the sooner and better they ripen.
Most fruit trees can best be left unpruned but with trained forms such as cordons or espaliers they need to be treated much the same as red currants or grapes. The single stem of a cordon or each limb of an espalier is permanent. On it shoots are trimmed back during summer to prevent crowding and making most into short stubs. Later these are reduced in length again in winter which causes them to form spurs on the permanent frame. Finesse is not actually required in summer pruning; many growers use shears or hedge-trimmers to reduce the masses of sideshoots. The winter prune needs to be a bit more neatly done, and opportunity taken to shorten old spurs that have got too long.. Apples, pears, apricots and to some extent sweet cherries can be regarded just like red currants. Indeed all of these can be maintained as cordons or espaliers in much the same way. However those varieties of apples known as tip bearers have the habit of predominantly fruiting on the tips of shoots formed the previous year. If these are cut back then little fruit can result, thus these sorts are best grown as naturally formed unpruned trees, - incidentally the majority of tip bearing apples are early fruiters. Peaches, nectarines and to some extent the plums and Morello cherries are more like black currants. They fruit best on young wood made the previous year and if this is cut back hard little fruit will result. Thus they can be left as free form trees, or if trained then are usually fan shaped and need the constant tying in of new young shoots and the removal of those that have just finished cropping -rather like black currants in fact. Indeed I have an idea peaches might be treated very much in the same manner as black currants and grown as multi-stemmed stools -but I believe no-one has yet tried it.