Fruit trees grown on dwarfing rootstock in pots/containers are suited to small gardens, courtyard gardens or patios providing a few procedures are followed, e.g.
When choosing the pot/container the first consideration should be stability and durability.
A pot with a small base can be come unstable in windy conditions particularly when the tree is in full leaf and or full of fruit.
The material the pot is made of should be frost proof to stop rapid degradation.
For instance clay pots are generally quite heavy and stable, but not always frost proof.
Another thing to consider is clay pots are often prone to drying out, so an impervious material e.g. plastic might be better.
Pots around 400-500 mm (15"-18") diameter/square are generally adequate.
Where trees remain in the one spot all year round then larger pots could be considered.
When filling the pot with compost firstly place 50mm (2”) of crocks, gravel, or broken up polystyrene over drainage holes.
Keep the base of the pot off the ground by standing it on purpose made feet or bricks.
This allows surplus water to drain off and prevents the pot sitting in pools of water during the winter months.
One should consider filling the pot with loam / soil based compost* rather than soil-less as this will give more stability.
It can also be an advantage to mix in a controlled slow-release fertiliser to sustain the plant during the growing season at this stage.
Leave a gap of 25-50mm (2”-3”) between the top of the compost and the rim of the container to allow for watering.
* If lime-free compost is required, then one should use ericaceous compost.
The first consideration is to select compact cultivars.
Next is the flowering period!
Cultivars must flower at similar times for reliable cross-pollination and subsequent fruit-set.
Cultivar choice also depends on the need for pollination partners.
Self-fertile cultivars pollinate themselves to some extent, but fruit best with a cross-pollinator.
Check here for a list of apple pollinating partners, there are similar lists available for pears.
Specialists are now producing family trees where two or three differing cultivars are grafted on to one dwarfing rootstock to help with this issue, however these need careful pruning to prevent one cultivar taking over.
Where possible locate the pot / tree in full sun.
Hardy fruit trees can be left outdoors over winter, but trees such as peaches and apricots should be put under cover in a cool greenhouse /tunnel.
If this is impractical surround them with some form of temporary shelter to keep the worst of the weather off.
Subject to location in the garden the trees can be trained as fans, espaliers and or cordons against walls and fences.
Alternatively, they can be trained against pergolas and trellis screens.
One can even consider stepover cordons where a pair of branches is trained parallel to the ground to form an edging for beds and paths.
Water liberally and often, and never allow the pot to become bone dry, watering may be required twice a day in summer.
Use rainwater for ericaceous plants.
When the embryo fruit has formed feed fortnightly with a high-potassium liquid feed e.g. tomato feed.
Root prune the tree prior to re-potting in alternate years (after leaf-fall) to avoid the plants becoming pot-bound.
Tease out the roots, trim the thicker roots, re-pot with fresh compost and controlled slow-release fertilizer into the same size pot.
In intervening years, it will suffice to replace the top 50mm (2") of compost.