Why a balcony makes a surprisingly good fruit garden

Balconies are often warmer, sunnier and more sheltered than the garden below, and that microclimate suits fruit far better than most people expect. A south-facing wall holds heat into the evening, which helps figs, peaches and early strawberries ripen properly. The real advantage, though, is control. You choose the compost, you manage the drainage, and when a late frost is forecast in May you can drag a pot into shelter rather than standing helplessly over a tree in open ground.

The trade-off is that a container is a closed system. There is no subsoil to draw on, so every drop of water and every nutrient has to come from you. Get that right and a few well-chosen pots will crop more heavily than a scrappy patch of border ever would.

Choosing pots, compost and drainage

Size matters far more than style. As a rough guide, allow 5 litres of compost per strawberry plant, 30 to 40 litres for a blueberry, and 40 to 50 litres for a dwarf apple — more if you can spare the space. Terracotta looks lovely but dries out alarmingly fast in wind, so glazed ceramic, thick plastic or fabric pots are usually kinder on a balcony. Whatever you choose, it needs several drainage holes, not one grudging hole in the middle.

• Stand pots on feet, bricks or a slatted tray so surplus water escapes and slugs have less of a motorway.
• Use a loam-based or peat-free multipurpose compost with a little added grit or perlite to keep it open.
• Never fill pots with garden soil. It compacts, drains badly and arrives complete with weed seeds.
• Top-dress each spring with fresh compost and a slow-release general fertiliser.

Strawberries: the quickest reward

If you grow nothing else, grow strawberries. They crop within a season of planting, tolerate smaller pots and look cheerful tumbling over a railing. Plant in early spring or autumn, setting the crown level with the compost surface — bury it and the plant rots.

Choose a modern variety such as 'Malling Centenary' or 'Cambridge Favourite' for a heavy June flush, or a perpetual type if you would rather have a steady trickle of fruit from July to September. Water little and often while flowering, then keep the compost evenly moist as the fruit swells. Straw or a handful of gravel under the berries keeps them clean and deters slugs. After cropping, cut off the old leaves, remove runners unless you want new plants, and feed to build the plants up for next year.

Blueberries: acid lovers worth the fuss

Blueberries are handsome shrubs with autumn colour, and they crop well in pots because you can give them exactly the compost they demand. Use ericaceous compost and never let them dry out — they have fine, shallow roots that sulk the moment they shrivel.

Water with rainwater wherever possible. Tap water in hard-water areas gradually raises the pH and the leaves turn yellow. If you must use tap water, feed with an ericaceous fertiliser or a sequestered iron tonic through the summer to keep them green. Two varieties flowering together give a much heavier crop than one alone; 'Bluecrop' and 'Patriot' make a reliable pair, while 'Top Hat' stays compact enough for a small balcony. Net the bushes as the berries colour, or the blackbirds will beat you to every one.

Dwarf apples and other small trees

An apple tree in a pot sounds ambitious, but apples grown on M27 or M9 rootstock stay genuinely small and crop happily for years. Columnar varieties, which grow as a single upright stem with short fruiting spurs, are ideal where space is tight.

Look for dessert varieties such as 'Discovery', 'Sunset' or 'Katy'. Most apples need a pollination partner, so if there is no other apple nearby, dab pollen between flowers with a soft artist's brush when they open. Thin the fruitlets in June, leaving one per cluster, so the branches are not dragged down by the weight. A 50-litre pot, a sunny spot and a sturdy stake will see a young tree settle in well.

Watering, feeding and looking after pots

From May to September a fruiting pot may need water every single day, and twice on hot, breezy days. Check by pushing a finger two inches into the compost rather than judging by the surface, which dries misleadingly fast.

• Spring: start feeding with a general liquid fertiliser as new growth appears.
• Flowering onwards: switch to a high-potash tomato feed once a week to encourage fruit rather than leaves.
• High summer: keep pots off hot paving if you can, and group them together to shade one another.
• Autumn: clear fallen fruit and leaves from the surface, which removes a favourite hiding place for vine weevil.
• Winter: raise pots onto feet, move them against a sheltered wall and wrap the rootball in bubble wrap or hessian if hard frosts are likely. Ease off watering but do not stop entirely — dry roots in a cold snap are what kills plants.

Every two or three years, in late winter, slide the plant out, tease away the outer roots and a third of the old compost, then repot into fresh mix and a slightly larger pot. Vine weevil grubs are the main pest to watch — if a plant wilts despite watering, tip it out and check the roots. Do that, feed and water steadily, and a modest balcony will quietly out-produce a whole row of hungry garden borders.