Guides

Which side of a fence gets the most sun?

North of the equator, the south-facing side of a fence gets the most direct sun over the year, and the north-facing side gets the least. The east-facing side gets its sun in the morning and the west-facing side in the afternoon, in about equal amounts. South of the equator, swap north and south.

Hours of direct sun on each side

These are the hours of direct sun at a spot 1 m (about 3 ft) out from the middle of a long fence 1.8 m (6 ft) high, on a clear day, with nothing else in the way.

The hours count every minute the sun is above a level horizon and not behind the fence, including the weak sun just after sunrise and before sunset. East-facing and west-facing sides come out within five minutes of each other, so they share a row.

Two things in these tables that surprise people

The north-facing side gets full sun in midsummer

In June the midday shadow of a 1.8 m fence is less than 1 m long, so a spot 1 m out is clear of it. Early and late in the day the summer sun is in the north-east and the north-west, so it shines straight onto the north side.

That only lasts while the sun is high: from early June to early July in London, and from late April to late August at 40° north. From early October to the middle of March the same spot gets no direct sun at all.

The south-facing side loses a few hours in midsummer

This is the same effect seen from the other side. In summer the sun rises and sets north of due east and west, behind the fence. Those are the weakest hours of the day, so plants hardly notice. At the equinox and in winter the south-facing side has sun from sunrise to sunset.

Further from the fence, the sides even out

Three metres out, the north-facing side is in sun all day from the March equinox to the September equinox. It still gets none in midwinter, when the midday shadow of a 1.8 m fence in London is nearly 7 m long. The guide to fence shadow lengths has the figures for other latitudes and heights.

What to grow on each side

South-facing (north-facing, south of the equator)

The warmest and brightest side, with sun all day in spring, autumn and winter. It suits tomatoes, fruit trained against the fence, and anything labelled full sun. It is also the side that dries out first.

North-facing (south-facing, south of the equator)

In shade from autumn to spring, and cooler and damper all year. The strip closest to the fence is the shadiest. It suits ferns, hostas and other plants labelled part shade or full shade.

East-facing

Sun from sunrise until around midday, then shade. The morning sun is gentler, so this side suits plants that scorch in a hot afternoon.

West-facing

Shade in the morning, then sun from around midday until sunset. It gets the same hours as the east-facing side, but in the hottest part of the day, so it is warmer and drier.

If your fence runs at an angle

Most fences don't run exactly north to south or east to west, and most spots have more than one fence or wall near them. Then the tables above are only a rough guide.