Pruning apple trees normally begins immediately after planting. Remove the central stem to just above the highest side branch. For the following 3 years, prune only the tips of the remaining main branches by one third in winter. Aim for about six main branches which will form the frame of your tree, with fruiting sub branches growing off of them. From the fourth year, some sub branches can be pruned out at the union where they join the main branch, to allow new sub branches to take their place.
However, if you are dealing with overcrowded mature trees then you may need to do some renovation pruning to restore the tree to a nice open shape and improve air circulation and light penetration. But be careful not to remove more than 25% of the canopy per year. This type of pruning should also be undertaken in winter. First remove all damaged, dead, crossing and diseased branches. Then remove any crowded branches to create a nice, even framework. Once you have thinned out the unwanted branches, you can begin a regular pruning regime, removing older fruiting spurs so that younger ones can replace them. You will need to spread this renovation process over several years though so it will require a bit of patience and may also reduce your crop initially.
We assume that we are talking about a dwarf tree which has 2 different varieties of apple grafted onto one rootstock such as our family apple tree.
Apples should be pruned during the winter months while the plants are dormant. Immediately after planting, trim back the grafted main branches by a third, always making the cut just above an outward facing bud.
For the following 3 years, prune the tips of the main branches and sub branches by one third in winter. Aim to develop the main branches to form the permanent framework of your tree, with fruiting sub branches growing off of them. From the fourth year, some sub branches can be pruned out at the union where they join the main branches, to allow new sub branches to develop and take their place. The sub branches will produce the best quality fruit.
We know this sounds complicated but there are lots of useful diagrams online and you are essentially pruning to create a ‘bush’ tree. Just bear in mind that when pruning ‘family apple trees’ you will need to treat each of the grafted stems individually as the different varieties are likely to have different growth rates. Remember to remove any suckers that develop at the base of the tree each year as well.
We have assumed you mean training your trees as an espalier (a main trunk with neatly pruned horizontal branches on either side). This is fine for apple trees but quinces are better trained in a fan shape as they don’t respond well to such restrictive pruning. It’s also worth checking that your apple tree is spur-bearing (bears fruit all along the branches) rather than tip-bearing as you wouldn’t get very many apples on an espaliered tip-bearing tree!