Why the garden after dark matters

Most British gardeners plant for bees and butterflies, then stop thinking about wildlife at dusk. That is a shame, because Britain has roughly 2,500 species of moth, and the vast majority do their work — feeding, pollinating, mating — between late afternoon and dawn. Many are in long-term decline, and a garden that offers nectar after sunset is doing something a bee-friendly border simply cannot.

Moths are not just night-time butterflies. They are pollinators in their own right, especially of pale, strongly scented flowers with deep nectar tubes that long-tongued species such as the elephant hawk-moth and the silver Y can reach. Leave the evening half of your garden unplanted and you leave half its potential wildlife uninvited.

What makes a flower a moth flower?

Night-flowering plants tend to share a handful of traits, and once you know them you can spot good candidates at a glance.

• Pale petals — white, cream, soft yellow or pink, which show up in low light.
• Scent released at dusk — fragrance peaks when pollinators are on the wing, then fades by morning.
• Nectar held deep in a tube or spur, often with a flat landing platform for moths to settle on.
• Flowers held open through the night rather than closing, as with white campion and evening primrose.
• Abundant, repeat flowering over a long season, so there is nectar on warm nights from May to October.

This is why a border of day-blooming daisies can look generous at noon and be almost silent by ten o'clock.

Native and long-established plants worth growing

You do not need anything exotic. Several of the best moth plants are natives, or plants that have been at home here for centuries.

• Honeysuckle (Lonicera periclymenum) — the classic. Its scent peaks in the evening and pulls in hawk-moths. Grow it up a fence or through a hedge that gets sun for most of the day.
• White campion and bladder campion — native, scented at night, with pale flowers that seem to glow at dusk. Both are easy from seed in a sunny, well-drained spot.
• Common valerian (Valeriana officinalis) — tall, pinkish-white heads with a sweet evening perfume, happy in damp or ordinary soil.
• Soapwort (Saponaria officinalis) — pale pink, generous, and lightly scented after dark.
• Sweet rocket (Hesperis matronalis) — naturalised here since the Middle Ages, purple or white, and much loved by moths.
• Evening primrose (Oenothera biennis) — a naturalised short-lived plant whose yellow flowers open visibly at dusk.
• Ivy (Hedera helix) — not scented in the same way, but its autumn flowers are one of the best late-season nectar sources for moths.
• Hemp-agrimony, wild marjoram, field scabious and greater knapweed — late-summer nectar for dusk-flying and day-flying moths alike.

Plant in generous groups rather than single specimens, and put the strongest scents near a path, patio or open window where you will actually notice them.

Feed the caterpillars, not just the adults

Nectar keeps moths alive; leaves keep the next generation alive. If you want a self-sustaining population rather than a passing stream of visitors, you need caterpillar foodplants, and that means tolerating a little untidiness.

• Leave patches of long native grass — cocksfoot, Yorkshire fog, fescues and meadow grasses feed many caterpillars.
• Allow bird's-foot trefoil, clovers, docks and nettles in a corner. Nettles are not wasted ground.
• Grow mullein, foxglove and willowherb for the species named after them.
• Keep a native tree or shrub — willow, oak, hawthorn, blackthorn or birch — if you have room. Each supports dozens of species.
• Leave seed heads and hollow stems standing over winter, and let leaf litter gather beneath hedges. Moths pupate in it.

A pile of logs, a hedge bottom left alone and a strip of unmown grass will do more for moths than any amount of summer bedding.

Turn the lights down low

Artificial light is one of the quieter pressures on night-flying insects. Moths drawn to a bright wall will circle it until exhausted, and they are easy prey while they do. Good lighting is part of good planting.

• Use warm, low-intensity bulbs and shield fittings so light points down at the path, not up and out.
• Fit motion sensors so lights come on only when needed.
• Close curtains and blinds at dusk, or set timers that cut outdoor lighting between dusk and dawn.
• Keep one corner of the garden genuinely dark, and put your scented plants there.

An evening ritual worth keeping

Start small: a pot of night-scented catchfly or sweet rocket by the back door, a honeysuckle on the fence, one patch of long grass left uncut through winter. Then take a torch out at dusk in July, sit still for twenty minutes, and watch what arrives. You may see silver Ys hovering, a burnished brass shining on a valerian head, or the sudden blur of an elephant hawk-moth working down a honeysuckle floret. That quiet shift change is one of the best-kept secrets of British gardening, and it costs nothing but a little patience and a few well-chosen plants.