Why grow upwards?

Floor space is the first thing to run out in a small garden, on a balcony, or along a narrow courtyard. Indoors, every pot lined up on a windowsill eats into the daylight the room behind it depends on. Growing vertically answers both problems at once: a wall that holds nothing but paint can hold herbs, salads, strawberries and trailing flowers, and a shelf can double your cropping area without spreading a single pot across the carpet. The secret is to plan the structure before you fall for the plants.

Start with the wall, not the plants

Aspect matters more than the colour of your planter. A south-facing wall bakes and dries out fast; a north-facing one stays cool and damp; east catches gentle morning sun, west takes the fierce late light. Walk round your space at three points in the day and note which walls are in sun at ten, at two and at six.

Weight is the other consideration. Brick and masonry will happily take a loaded trough on proper anchors, but plasterboard needs a stud finder and fixings driven into timber, or a decent cavity fixing. Keep anything heavy away from doorways, and never hang a full trough directly above a bench where people sit.

• South or west: tomatoes, chillies, aubergines, rosemary, thyme, trailing strawberries.
• East: salads, chard, parsley, mint, calendula, nasturtiums.
• North: cut-and-come-again leaves, rocket, chervil, ferns, ivy and most foliage plants.

Wall planters: pockets, troughs and guttering

Three formats do most of the work. Felt pocket planters are cheap, light and drain freely, which suits salads and herbs; they dry out quickly, so mix in plenty of compost and consider a moisture mat behind the pockets. Rigid troughs, roughly 20–30cm deep, hold more compost and need watering far less often — ideal for tomatoes, bush beans and peppers. Lengths of guttering or downpipe, cut and capped, make superb shallow runs for rocket, cut leaves and annual herbs, and they can be screwed to a fence rail in minutes.

Plant in staggered rows rather than a neat grid, so leaves in the row below do not sit in the shadow of the row above. Put the tallest growers in the top pockets and let trailing plants — tumbling tomatoes, strawberries, creeping thyme — spill from the bottom. In high summer a 60cm trough can lose a litre of water a day, so mulch the surface with gravel or wool pellets and, if you can, run a simple drip line on a timer. It is the single change that turns a pretty wall into a productive one.

Shelves and tiered staging

Indoors, a narrow shelving unit placed in front of a bright window gives you several growing layers in the footprint of one. Keep shelves shallow — 20–25cm is plenty — and leave roughly 30cm of clearance from the glass, so plants are not scorched in summer and the room still receives light. Slatted shelves let daylight filter down to the level below; solid ones simply shade it. A quick coat of white paint on the wall behind will bounce light back onto foliage and keep plants from stretching.

Outdoors, tiered staging works the same trick against a fence or house wall, raising pots into better light and letting you reach everything without bending. Waterproof trays and saucers underneath are non-negotiable indoors, and a sheet of oilcloth on the shelf below saves a great deal of scrubbing. Turn every pot a quarter turn each week so growth stays even.

Trellises, obelisks and climbing crops

Climbers give the biggest harvest per square metre of any group of plants, but they need their support in place before sowing. Tension wires run between vine eyes are neat and almost invisible; wooden trellis fixed with a 5cm gap from the wall allows airflow behind the foliage and room to tie in stems. Netting with a 15cm mesh suits peas and beans, while soft twine wrapped round vertical wires is kinder to tomatoes and cucumbers.

Reliable choices include climbing French and runner beans, peas, cordon tomatoes, cucumbers, Malabar spinach and nasturtiums. Fruit works too: a fan-trained cherry or a column apple against a sunny wall earns its space many times over. Fix the frame securely, pinch out growing tips when plants reach the top of their support, and keep tying in as stems lengthen.

Watering, feeding and light discipline

Vertical gardens dry out faster than ground-level pots because more of their surface is exposed. Water in the morning, water slowly until it runs from the drainage holes, and check by weight — a light pot is a dry pot. Feed fruiting crops weekly with a high-potash liquid feed once flowers set; leafy crops need only a monthly boost.

• Group pots by thirst, so you are not soaking drought-lovers alongside salads.
• Rotate indoor plants weekly and wipe windows monthly to keep light levels up.
• Trim anything on a top shelf that starts shading the plants below.
• Empty saucers after watering to prevent root rot and, indoors, to protect sills.

Done well, a vertical garden is quietly generous. It asks for a little planning, a few good fixings and a watering routine you can keep to — and in return it turns bare walls and wasted shelf space into somewhere genuinely worth harvesting from.