Start by understanding what you are up against

Most British small gardens have one. That north-facing strip behind the shed, the corner beside the fence where the soil stays cold and the moss moves in, the narrow passage down the side of the house that only ever sees an hour of sun. These spaces rarely fail because there is no light at all. They fail because the eye has nowhere to travel. A dark corner is not just dim, it is a dead end.

Mirrors and lighting solve that problem between them. One gives the eye somewhere to go, the other gives it something to look at. Get both roughly right and a gloomy eight-foot square starts to feel like a proper room. Get them wrong and you end up with a fairground. The difference is mostly restraint.

Choose a mirror that can survive a British winter

An ordinary indoor mirror left outside will fail within a season. Moisture creeps behind the silvering, the edges blacken, and no amount of polishing brings it back. Purpose-made outdoor mirrors use acrylic or safety-backed glass with sealed edges and a solid frame, and they are worth the extra cost.

Acrylic is lighter, cheaper and will not shatter, which matters if children play nearby, but it scratches easily and can bow in strong heat. Safety glass gives a truer, sharper reflection and holds its shape; it is heavier and needs a firmer fixing. Either way, mount onto a backing board or a sound fence post rather than screwing directly into a thin panel.

One caution worth knowing: avoid hanging a mirror where it catches direct summer sun at an angle. A curved or highly polished surface can concentrate light enough to scorch nearby planting, and in rare cases acts as a magnifier. In a genuinely shady corner this is unlikely to be a problem, but check the path of the sun before you commit.

Positioning: reflect something worth looking at

The common mistake is fixing a mirror flat to a wall and mirroring the patio back at yourself. It adds light but no interest. Angle it instead so it captures something worth stealing: a sunlit border at the far end of the garden, a pale tree trunk, a bird feeder, the sky above the roofline.

• Hang at seated eye level if you use the corner for sitting. Standing height is usually too high.
• Tilt two or three degrees downward so the mirror catches planting rather than blank sky.
• Hide the bottom edge behind ferns, hakonechloa or a low pot. A mirror that ends in a hard straight line reads as a mirror; one that appears to continue into foliage reads as space.
• Use a slim panel on a boundary fence, a freestanding arched mirror leaning behind pots, or a mirrored back panel inside a shed niche or arbour.
• Be sparing with mirrors facing one another. The infinity effect is disorienting in a small space and quickly looks like a trick.

Lighting that warms rather than interrogates

Colour temperature matters more than raw brightness. Choose warm white fittings around 2700K. Cool white at 4000K and above makes damp shade look clinical and turns green foliage grey. Layer your lighting rather than flooding the space with one source.

• Uplighting: a spike or wall uplighter at the base of a shrub throws shadows up a fence and gives instant depth. One is usually enough.
• Low-level fixtures: bollards of 300–400mm and step lights at very low output, used to trace a route rather than illuminate it.
• Grazing: a wall washer or a fitting set close to brick or timber reveals texture you would otherwise never see in shade.
• Social light: a single dimmed festoon or lantern over a bench, warm and low, for evenings outside.

Keep every bulb out of the eyeline. Point sources should be shielded by foliage, a hood or a small baffle. If you can see the lamp itself from where you sit, you have the angle wrong.

The practical side, briefly

Solar lights are tempting but unreliable in deep shade, because they need direct sun to charge. Mains low-voltage is the better answer where the corner is genuinely dark. Fittings under cover should be at least IP44; anything fully exposed should be IP65. Cable should be armoured where it crosses a border or lawn, and the circuit should be RCD-protected. Anything involving mains wiring deserves a qualified electrician, and it is money well spent.

Run the lights from a timer or photocell so the corner lights itself at dusk, and fit a dimmer if you can. Full brightness at 5pm in July looks absurd; a gentle glow at 10pm in November is the whole point.

Planting that makes the light work harder

Mirrors and lamps are only half the job. Pale, glossy and variegated foliage carries low light far better than dark green, and white flowers glow at dusk in a way that colour cannot.

• Structure: Fatsia japonica, Sarcococca confusa for winter scent, bamboo in a root barrier.
• Texture: Dryopteris erythrosora, Polystichum setiferum, hakonechloa for movement.
• Ground cover: Epimedium, Liriope, lamium, tiarella.
• Dusk glow: white foxgloves, Nicotiana, Hydrangea 'Annabelle'.

Mulch with pale gravel rather than dark bark, and paint the boundary wall a warm off-white or soft sage. Pure brilliant white looks cold and shows every mark. Clean the mirrors with mild soapy water twice a year, check the fittings before winter, and nudge the angles as planting fills out. A fern that hides a mirror in August is not a failure, just a prompt to adjust.