Gardening Around the Midge: Timing, Wind and What Deters Them

The gardener's favourite hour and the Highland biting midge's favourite hour are the same one: early evening, as the light softens and the air cools. Two defences hold up best: working around the midge's activity pattern, and using wind, which midges cannot fly in above about 5.5mph, in how the garden is laid out. Repellent on skin helps too, whereas most deterrent planting is advice borrowed from a different insect.

Where in Scotland this matters

The Highland biting midge occurs throughout Scotland and is most abundant in the west and north, where boggy, acidic ground suits breeding. Its stronghold is the west coast, the Highlands and the islands. Gardens in the drier east generally have less of that habitat close by, so pressure there tends to follow local wet ground. Midges are seldom found above about 500 metres, where wind limits flight, so higher exposed ground carries less risk than a sheltered glen at the same latitude. In the west Highlands, Argyll and the islands, treat midges as a season-long constraint on when and where you garden; further east, it comes down to whether the garden has a damp, undrained corner.

What the midge is, and what it breeds in

The insect behind most Scottish midge misery is Culicoides impunctatus, the Highland biting midge. There are around 35 species of midge in Scotland, but this one is the dominant biter. Only females bite, because they need a blood meal to develop eggs. Eggs are laid on moist soil, often among rushes, and the larvae live in the watery top layers of the soil: up to 700 larvae per square metre of suitable ground, and up to 24 million per hectare in ideal habitat.

That habitat matters because many "garden midge" articles are really describing chironomid gnats, small non-biting flies that swarm around ponds and outdoor lights. The Highland midge is not a pond insect. It breeds in wet, acidic, poorly drained ground: boggy corners, badly drained lawns, rush-infested rough grass, and damp ground near dung heaps on farms and smallholdings. A garden that backs onto boggy, acidic ground is next to a breeding site. Improving drainage in permanently wet corners and keeping rushy rough ground to a minimum is the closest thing to a habitat-level defence a gardener has.

The clock problem

C. impunctatus is most active at dawn and dusk, and is less active in bright, sunny, breezy conditions than in overcast, still, humid weather. Light is the key factor, so dull overcast days can bring many bites even at midday.

Do the tasks that need lingering outdoors, such as weeding, planting out and harvesting, in the hours either side of midday, when the sun is highest and any breeze is most likely. Push watering, which many gardeners save for the evening, to first thing in the morning once the dawn peak has passed, or accept that watering at dusk in midge season means covering up properly.

The season starts in late April in a mild year (SRUC's midge traps began catching in late April in 2025), and numbers peak in July and August. The first autumn frosts kill the survivors, which is why a calendar date does not end the season. SRUC names temperature as the key driver of how long the season runs, so a cold, late spring buys a shorter season and a mild one the opposite.

Wind: the one defence with real teeth

Midges are small, weak fliers. At wind speeds over about 5.5mph (8.8km/h) they are unable to fly, landing on vegetation instead. On the Beaufort scale that is within force 2, a light breeze, well short of what most people would call a windy day.

A garden does not need to be exposed to get relief. It needs a seating or working area that is not sheltered from every direction. That cuts against the instinct to build a cosy, enclosed suntrap with hedging or fencing on all sides, which is excellent at creating the still air midges prefer. A seating area open on at least one side to the local prevailing breeze, while sheltered from the coldest or most driving weather, gets the benefit without being unusably exposed.

Smoke is commonly credited with a similar effect, on the reasoning that midges home in on carbon dioxide and body scent and smoke disrupts that trail. It is a plausible, widely repeated claim and not a measured one, so a fire pit or chiminea near a seating area is a reasonable bet, not a guaranteed fix.

Repellents on skin

NatureScot's advice is to use repellents containing DEET. A Scottish field trial in the 1990s tested a eucalyptus-based repellent (PMD) against DEET on people exposed to C. impunctatus, and both gave high protection for several hours. Reapply after sweating, washing or swimming, as the product instructions say. A head net and long sleeves help when you have to work at the peak hours. This is the one way to protect yourself that works regardless of the weather or the site.

Deterrent planting

The standard plant list (citronella, lavender, mint, basil, rosemary, marigold, lemon balm, garlic, eucalyptus) is recycled from generic "garden midge" content about non-biting gnats, not the Highland biting midge. None of these plants has institutional or peer-reviewed backing for reducing C. impunctatus in a garden. That does not make them bad plants, but none is a proven midge deterrent.

Bog myrtle (Myrica gale), the aromatic native shrub of Highland bogs, is the exception with a real Scottish trail. Scots used it in the past as a repellent, historically carried or rubbed on, and research on oil from its leaves has been done against the biting midge. Bog-myrtle-scented products are sold, and some people also use Avon's Skin So Soft, a moisturiser with no midge-specific design, on a word-of-mouth basis. The tradition is old, but no field trial shows how much protection a living bog myrtle in a border, as opposed to its oil on skin, gives someone sitting nearby. It is a good native shrub for a damp, acidic Highland garden on its own merits, not a solved repellent.

Building a midge-lighter garden

Applied together over a season, timing, wind and drainage compound. None guarantees a midge-free evening, but together they make a materially different garden to sit in by July. Small, permanently damp spots near where people sit are worth a second look too: a shaded compost heap that never dries out, a mulchA layer of material spread over the soil around plants to suppress weeds, retain moisture, and improve soil structure as it breaks down. Full definition → pile kept wet, a stack of logs on bare damp soil. They do not breed midges the way rushy, undrained ground does, but they keep the immediate area humid and sheltered, which midges favour as a daytime resting place. Moving seating away from the compost heap, or lifting a log pile onto a pallet so air reaches underneath, costs nothing.

Common questions

Sources