Start by Reading the Space

A side return is rarely generous — most are somewhere between one and a metre and a half wide, running the length of the house between kitchen window and boundary wall. Before you buy a single plant, spend a week noticing how the space actually behaves. Where does the sun land, and at what time? Does the passage funnel wind from the front of the house to the back? Does water sit in the corner by the downpipe after rain? These small observations will save you money and heartbreak later on.

Be honest about your aspect. A passage running north to south will catch sun along its length for part of the day, whilst one running east to west may stay in shade until late afternoon. In deep shade your palette is smaller, but it is a good one: ferns, ivy, climbing hydrangea and sarcococca all cope admirably. Then decide what you need this space to be — a route to the garden, a place to store bikes and bins, a view from the sink, or a spot to sit with a coffee. It can be several of these, but let one lead the design.

Light the Floor and the Boundaries

In a narrow corridor, light is the whole game. Pale surfaces bounce what little arrives, so swap dark gravel and charcoal slate for light grey porcelain, cream-toned stone or pale pea shingle. Gravel is inexpensive, drains beautifully and softens the sound of footsteps, though it needs a firm edge to stop it wandering onto the patio.

Walls and fences deserve the same treatment. A soft off-white, a warm grey or a pale sage will lift a shaded passage far more effectively than a dark stain, and painting the boundary on both sides makes the space feel wider than it is. Repair crumbling pointing and wash down brickwork before you plant anything against it, because damp, flaking mortar is a climbing plant's worst enemy. Keep to two boundary colours at most, and repeat them at the far end so the eye is drawn along the corridor rather than stopped by it.

Grow Upwards with Slim Trellis and Climbers

With so little ground to play with, the vertical plane does the heavy lifting. Fix narrow trellis panels — 30cm to 45cm wide is plenty — to battens so air can move behind the foliage and the wall stays dry. On brick, tensioned stainless steel wires are neater and almost invisible once the plants have knitted through them.

Choose climbers to suit the light you have. Star jasmine (Trachelospermum jasminoides) is evergreen and gloriously scented in a sheltered, sunny spot. Climbing hydrangea will thrive on a cool north wall, and winter jasmine flowers cheerfully through the coldest months in shade. Clematis armandii and most climbing roses want warmth and sun. Avoid thuggish self-clingers such as ivy and Virginia creeper on old mortar, however tempting their speed.

For quick cover in the first season, annual climbers are hard to beat. Sweet peas, cobaea and thunbergia will scramble up a tripod or a length of wire in weeks, and you can pull them out in autumn without any commitment.

Plant in Slim, Pale Layers

Keep borders to 30cm or 40cm deep and plant in layers instead of spreading outwards. Columnar shrubs give height without girth: Fatsia japonica, mahonia, Pittosporum tenuifolium and the upright euonymus all earn their keep. Underplant them with hakonechloa, libertia or pheasant's tail grass for movement, and dryopteris or polystichum ferns where the ground stays damp.

• Scent in winter: sarcococca, Lonicera fragrantissima and Daphne odora will perfume the whole passage from January.
• Pale flowers: white foxgloves, astrantia, Japanese anemones and white hydrangeas read well in low light.
• Silver foliage: stachys and lavender brighten a sunny wall and set off whites beautifully.
• Bulbs: snowdrops, white alliums and pale tulips tucked into gaps and pots give you months of interest for very little outlay.

Repeat a handful of plants along the length rather than collecting one of everything. Repetition calms a narrow space and makes it feel considered.

Practical Kit That Earns Its Place

Every object in a side return should justify its footprint. A slim bench, a folding bistro set, wall-mounted shelves for pots and a well-designed bin or bike store will keep the route clear without feeling like a corridor of utility. If you have room, a water butt against the wall saves countless trips with a watering can, and a drip line or soaker hose is a sensible investment for pots that dry out fast.

Lighting transforms the space after dark. Small uplighters at the base of climbers graze the foliage, and a catenary wire strung between house and wall will carry festoon lights for summer evenings. Choose warm bulbs and avoid anything stark and white.

Maintenance, Wind and the Long View

Side returns funnel wind, so tie climbers in regularly and choose tough, weatherproof plants rather than delicate ones. Damp shade encourages slugs, so set nematodes in spring and mulch with grit around hostas and newly planted perennials. Prune climbers annually to keep them clear of windows, gutters and air bricks, and give everything a seaweed feed in early summer.

Twenty minutes a week is usually enough to keep a narrow garden looking sharp: a sweep of the paving, a snip here and there, a check on ties. Do that much and your passage becomes what it should be — a green corridor that draws you out to the garden rather than a place you hurry through.