Why plants save their scent for after dark

A garden at dusk is a different place. The colours drain away, the birds quieten down, and suddenly the air carries something you did not notice all afternoon. That is not your imagination. Many plants have evolved to release their scent only in the evening, timed to the shift change in pollinators.

Bees and butterflies are largely daytime workers, guided by colour and shape. After sunset, the night shift takes over: moths, and in some gardens bats hunting them. Moths navigate a dark, cluttered world with a superb sense of smell, so plants that want their attention have to shout with fragrance rather than petals. The flowers tend to be pale, often white or cream, so they still glow faintly in low light, and frequently tubular or funnel-shaped, which suits a moth's long tongue.

The practical upshot for you is simple. If you choose the right plants, your patio can smell extraordinary exactly when you are most likely to be sitting on it, glass in hand, watching the last of the light go.

The best night-scented plants for a UK garden

You do not need a large plot. A few well-chosen plants in pots by the back door will do more for your evening than a whole border of daytime colour.

• Evening primrose (Oenothera biennis) — the classic. Pale yellow flowers open in front of your eyes at dusk, often in under a minute, and the scent is sweet and citrusy. It is a biennial, so sow one year for flowers the next, and let it self-seed in gravel or a sunny border.
• Night-scented stock (Matthiola longipetala subsp. bicornis) — the strongest scent per gram of plant you will ever grow. The flowers are small, greyish and frankly dull by day, then shut entirely; by evening the whole plant smells of cloves and vanilla. Sow direct in April and again in late May for a longer run.
• Tobacco plant (Nicotiana) — N. sylvestris is tall, stately and white, while N. alata varieties such as 'Lime Green' are shorter and suit pots. Both release their perfume in the evening and keep going well into autumn if deadheaded.
• Honeysuckle (Lonicera periclymenum) — our native honeysuckle is a magnet for moths, including the spectacular elephant hawkmoth. Grow it up a pergola or over a shed where you can sit beneath it.
• Sweet rocket (Hesperis matronalis) — cottage-garden favourite, scented in the evening and a good nectar source. It seeds about freely, which is usually a bonus.
• Night-scented phlox (Zaluzianskya ovata 'Midnight Candy') — small, neat and perfect for a container near a seat, opening white flowers that age to pink.
• Abyssinian gladiolus (Gladiolus murielae) — late-summer elegance with a delicate evening fragrance, ideal at the back of a sunny border.

Plant for scent where you actually sit

Scent is carried on cool, humid, still air, and it travels downhill. That means a plant at the bottom of the garden will scent the lawn, not your chair. Put your fragrant plants within two or three metres of where you sit, and ideally on the sheltered side, so the breeze brings the perfume towards you rather than snatching it away.

Warm paving and brick walls help. A Nicotiana against a south-facing wall that has soaked up sun all day will release far more scent in the evening than the same plant in open ground. Grouping several fragrant plants together concentrates the effect, and pots give you the freedom to move them as the season shifts — closer to the door in June, out on the patio in August.

Avoid planting night-scented flowers next to anything strongly perfumed itself, such as lavender or roses, unless you want the fragrances to compete and cancel each other out.

Make your evening garden work for moths and bats

A wildlife-friendly evening garden is more than a scent machine. Moths need nectar, shelter and somewhere for their caterpillars to feed, and many of the plants above supply all three.

• Choose single, unfussy flowers. Double blooms often have no accessible nectar.
• Leave a patch of long grass and some leaf litter over winter — a huge number of moth species pupate or overwinter in it.
• Skip pesticides entirely. A garden with a few nibbled leaves is a garden with a food chain in it.
• Add a shallow water source, such as a saucer of pebbles and water, for moths and other insects to drink.
• Plant a mix that flowers in succession, so there is nectar from May right through to the first frosts.

Bats will follow the moths. If you have mature trees nearby and a dark corridor along a hedge or fence line, you may well see them stitching through the dusk above your border.

Lighting that doesn't spoil the show

Bright white security lighting is the enemy of a good evening garden. It washes out your night vision, hides the shape of the planting and disrupts the moths you have just invited in.

Keep lighting low, warm and directed downwards, ideally on a timer or motion sensor. Solar stake lights along a path are usually enough to stop you tripping, and a candle or two on the table beats a floodlight every time. Where you can, leave the far end of the garden properly dark — that is where the wildlife will be.

Keep the perfume going from June to September

Succession is everything. A single sowing of night-scented stock will give you a few glorious weeks and then nothing, so sow a small pinch every three or four weeks from April to July in a spare corner of the veg patch or in a pot.

Deadhead tobacco plants and gladioli regularly to keep them flowering. Water in the evening rather than the morning during dry spells, which suits these plants and reduces evaporation. A mulch of garden compost in late spring will keep them growing strongly without much fuss.

Finally, do go out. The whole point of a night-scented garden is that it asks nothing of you after dark except to sit down and notice it.