Start with the space you actually have

Most narrow city courtyards are not really gardens in the traditional sense. They are strips of outdoor space behind a Victorian terrace or a modern townhouse — often three metres wide and six metres long, bordered by brick walls and overlooked from two or three sides. The trick is to stop treating it as a small garden and start treating it as a room: one with a floor, walls and a ceiling of sky. Once you do that, the design decisions become far clearer.

Before you plant anything, spend a week watching how the light moves. A north-facing courtyard may get direct sun for only an hour or two. A south-facing one can become uncomfortably hot by mid-afternoon. Both are workable, but they call for different plants and different seating positions. Note where the sun lands, where damp patches sit after rain, and which corner feels most sheltered. That knowledge will save you a fortune in plants that sulk and die.

Use vertical planting to double your growing space

In a narrow courtyard, walls and fences are your greatest asset. They represent far more square metreage than the ground, and they are exactly where wildlife wants to be — sheltered, warm and out of reach of cats. Climbers soften hard boundaries and make the space feel larger than it is.

Good choices for British courtyards include honeysuckle, whose evening scent feeds moths; star jasmine for a sheltered south or west wall; and ivy, unglamorous but superb for nesting birds and late nectar. A climbing rose will cope with a sunny wall and give hips for the birds in autumn.

• Fix trellis or wire grids to walls and fences so climbers have something to grip.
• Use tall, narrow pots at the back of borders to add height without eating floor space.
• Hang wall-mounted planters at eye level for herbs and trailing flowers.
• Train a small fruit tree flat against a sunny wall as an espalier.

Stacking plants this way creates layers of shelter — exactly what insects, frogs and small birds need to move safely through the space.

Paint the walls pale to bounce light and stretch the view

Dark brick and grey fencing absorb light and make a narrow courtyard feel like a tunnel. A coat of pale, muted paint — soft chalk white, sage or a warm limestone tone — reflects what light you have and pushes the walls visually outwards. It is one of the cheapest transformations you can make.

For wildlife, the finish matters more than the colour. Use a breathable masonry paint on brick or render, and avoid anything glossy on timber. If your fence is old and full of gaps, leave a little of it unpainted and add a hedgehog highway: a 13-centimetre square gap at the base of a panel, so wildlife can pass between neighbouring gardens. Small gesture, surprisingly large effect.

Pale walls also make the green of your planting sing. If you want to add depth, paint the back wall a shade lighter than the side walls. The eye reads the lighter surface as further away, and the courtyard instantly feels longer.

Choose a slim bench that earns its place

Seating in a narrow courtyard should be narrow itself. A deep garden sofa will swallow half your floor. Look instead for a slim bench — no more than 40 to 45 centimetres deep — in weatherproof timber, powder-coated steel or rattan. A low back keeps sightlines open; a backless bench can double as a table for trays and drinks.

Position it against the longest wall or in the sunniest corner, facing the best view. If space is truly tight, a fold-down bench hinges flat against the wall when not in use. Add weatherproof cushions stored in a lidded box that doubles as a side table, and keep secateurs and a watering can tucked underneath so the space never feels cluttered.

Repeat a handful of plants for a calm, unified feel

The single most effective design trick in a small space is repetition. Rather than collecting one of everything, choose three to five plant varieties and repeat them along the border, in pots and up the walls. Repetition creates rhythm, and rhythm reads as intention. It also makes the courtyard feel larger, because the eye travels along a pattern rather than stopping at each new plant.

A simple palette for a British courtyard might be ferns for shade, lavender for sun and scent, Japanese anemones for late colour, and a single climbing rose. Each one feeds pollinators and earns its keep across several months, giving green structure, summer flowers and autumn interest. Add a few evergreen shrubs in pots to hold the shape through winter.

Layer in wildlife-friendly details and cosy evening light

Wildlife-friendly gardening in a courtyard is mostly about small, consistent provision. A shallow dish of water at ground level gives birds and hedgehogs a drink and a bath. A small log pile in a shady corner becomes a home for beetles and solitary bees. A few native plants — foxgloves, ox-eye daisies, wild marjoram — will bring in bees and butterflies that bedding plants simply will not.

Then make it cosy for you. Warm white solar fairy lights strung through a climber transform the space after dark. A single lantern on the bench, a pot of mint by the door and a wool throw for cooler evenings turn a narrow passage into somewhere you genuinely want to sit. The best courtyard gardens are not the cleverest ones; they are the ones that get used.