Start with the rootstock, not the variety

It is tempting to leaf through a catalogue and choose an apple purely on flavour, but in a small garden the rootstock does most of the work. The rootstock is the root system onto which the fruiting variety is grafted, and it governs how tall the tree will eventually grow, how quickly it crops and how well it anchors itself. Get this decision wrong and you will spend the next decade hacking back a tree that desperately wants to be four metres tall.

Three rootstocks are worth knowing. M27 is the most dwarfing of the widely available options, producing a tree of roughly 1.2–1.8m. It suits large containers and the tightest of courtyards, though it needs permanent staking and more generous watering and feeding than the others. M9 is the best all-rounder for a modest plot: expect 1.8–2.5m, fruit from two or three years after planting, and a tidy, manageable habit. M26 suits a slightly more generous space, reaching 2.4–3m, and copes better with heavier clay soils. Anything more vigorous — MM106, M25 — belongs in an orchard, not a back garden.

Match the training form to your space

A tree's shape matters as much as its size. Decide where it will live before you buy, then choose a form that fits that footprint.

• Cordon: planted at about 45 degrees or upright, 60–75cm apart, reaching roughly 2m. Brilliant along a fence or wall, and heavy cropping for the space it takes.
• Espalier: horizontal tiers trained against a wall or fence, spreading 3–4m. Needs a spur-bearing variety and annual summer tying-in.
• Stepover: a single low tier around 40–50cm tall — perfect as an edible edging along a path or veg bed.
• Dwarf bush: the traditional open-centred tree on M27 or M9, with a spread of about 1.5m.
• Columnar: varieties such as 'Waltz' and 'Bolero' that crop on short spurs close to the trunk, occupying barely a square metre.

Varieties that earn their place

In a small garden every apple needs to justify itself, so favour varieties that crop young, crop reliably and taste worth the trouble. 'Discovery' is an early, bright-flavoured apple with a useful trick: it is partially self-fertile and crops heavily, though the fruit does not store. 'Katy' is another self-fertile option with crisp, juicy fruit in September. 'Egremont Russet' is partially self-fertile too, and its nutty, firm flesh keeps until Christmas.

For reliability in our damp climate, look at 'Fiesta', 'Sunset' and 'Spartan', all of which resist scab better than the notoriously fussy 'Cox's Orange Pippin'. 'James Grieve' is a fine dual-purpose apple and an excellent pollinator. If you want a cooker, 'Bramley' is a triploid: it cannot pollinate anything, including itself, so it needs two other varieties nearby. A single tree of 'Greensleeves' or 'Kidd's Orange Red' may be a wiser use of the space.

Pollination and siting

Most apples need a partner that flowers at the same time, so if you have room for only one tree, choose a self-fertile variety or a columnar type. Otherwise plant two varieties from the same or adjacent flowering groups — usually groups 2, 3 and 4 overlap well — within about 20 metres of each other. A neighbour's apple tree or a nearby crab apple can do the job just as effectively.

Site your tree in full sun, at least two metres from a boundary, and avoid frost pockets at the bottom of a slope, where late spring frosts can strip the blossom. Apples prefer a fertile, well-drained soil at around pH 6.0–7.0. Bare-root trees, planted between November and March, establish far better than pot-grown ones and are considerably cheaper.

Planting, pruning and the first few years

Dig a hole wide enough to take the roots spread out, but no deeper than the tree was growing before. Work in some well-rotted compost, firm the soil gently around the roots, and water thoroughly. Stake M27 and M9 trees permanently with a sturdy stake and a soft tie, and mulch with a ring of compost kept clear of the trunk.

Pruning depends on the type. Spur-bearing cordons and espaliers are pruned in late summer, cutting new shoots back to three or four leaves above the basal cluster. Tip-bearing varieties — 'Discovery', 'Worcester Pearmain' and others — carry much of their fruit at the ends of young wood, so cutting those tips off costs you next year's crop. If you are unsure, prune lightly and watch where the fruit forms.

In June, thin clusters to a single apple every 15cm. It feels brutal, but the remaining fruit swells larger, and thinning helps break the biennial cropping habit that many older varieties fall into.

Growing in containers

If your only space is a patio or balcony, all is not lost. Choose a variety on M27 or M9 and plant it in a container at least 45–50cm across, using a loam-based compost such as John Innes No. 3. Keep it in full sun, water regularly through summer, and top-dress each spring by scraping off the top few centimetres of compost and replacing it. Feed with a general-purpose fertiliser from March, then switch to a high-potassium feed once the fruit starts to swell. Expect a modest harvest — perhaps 5–10kg from a well-tended container tree — but there are few pleasures quite like picking your own apple a few steps from the kitchen door.