Greenhouse orientation in the UK

Ridge direction is the useful measurement

When gardeners ask which way a greenhouse should face, they often mean the door. The more important line is the ridge running along the roof peak. A greenhouse with an east–west ridge presents one long side towards the south; a north–south ridge lets sun move across both long sides during the day.

Use a compass or map to establish direction, then look at the real horizon. Houses, trees and fences alter when sunlight reaches the glazing. A perfectly oriented greenhouse behind a garage can receive less usable light than a slightly rotated greenhouse in an open part of the plot.

East–west for lower winter sun

The RHS orientation guidance notes that an east–west orientation can slightly extend winter light. In the UK, the sun remains low and tracks across the southern sky in winter, so the long south-facing roof and wall can intercept more of it. This can help when winter use is the priority, provided the site is not shaded by buildings or trees.

The north side will receive less direct sun and can stay cooler or damper. Keep glazing clean, avoid tall storage on that side and leave enough space outside for air and maintenance. In summer, the south side may receive intense exposure and need shading.

North–south for summer crops

With a north–south ridge, the east side receives morning sun and the west side receives stronger afternoon sun. Light moves across the greenhouse rather than remaining concentrated on one long face. The RHS identifies this as a good orientation for summer crops such as tomatoes.

That movement can distribute growth more evenly across opposing beds. It does not guarantee uniform conditions: the west side may run hotter in late afternoon, and nearby boundaries can still create persistent shade.

Orientation cannot repair a poor site

Do not sacrifice drainage, safety or usable access to achieve an exact compass bearing. A greenhouse should not be placed under branches, in a waterlogged hollow or in a severe wind funnel simply because the ridge points east–west.

Rank the decisions in this order:

1. a stable site with open light and safe clearance;
2. shelter from severe wind and a secure anchoring route;
3. convenient door, water and maintenance access;
4. the best seasonal ridge orientation that fits those constraints.

Our greenhouse positioning guide explains the full site survey.

Lean-to orientation

A lean-to is governed by the available wall. A south-facing wall captures strong light and stores heat, which can help in cooler months but increase summer overheating. An east-facing wall receives gentler morning sun. A west-facing wall is exposed to stronger afternoon heat, while a north-facing wall may be too shaded for many demanding crops.

Assess the wall itself: overhanging eaves, windows, vents, downpipes and neighbouring buildings alter light and installation. Masonry can release stored warmth after sunset, but only if the greenhouse is designed and fixed for that wall.

Wind direction and doors

Ridge orientation also changes the surface presented to prevailing wind. A gable may shed wind differently from a long glazed side, but product design and local turbulence make simple rules unreliable. On an exposed plot, choose the orientation that reduces risk without creating deep shade, then follow the manufacturer's anchoring requirements.

Avoid directing an outward-opening door into the strongest wind. Provide a positive catch and keep roof vents closed during storms. A door placed for easy daily access is more valuable than one moved to satisfy a compass rule.

Slopes and local microclimates

South-facing slopes and walls receive more solar energy; north-facing areas remain cooler. Low points can collect cold air, while urban walls create warm pockets. These site effects may be stronger than the difference between two ridge directions.

Observe frost, dew and snowmelt patterns. An area that stays frosty long after the rest of the garden warms is a poor choice for early propagation. An area that dries immediately but is exposed to hard wind may need porous shelter.

Crop layout inside the greenhouse

Orientation should influence staging. Avoid putting permanent tall shelves or opaque storage where they shade the main growing bed. Place tall summer crops so they do not block every tray behind them, and rotate movable plants as the sun changes.

In an east–west greenhouse, taller crops are often best managed towards the north side so they do not shade lower plants to the south. In a north–south house, divide vigorous crops between sides or train them so light can move through the canopy.

Final orientation check

Mark the footprint, stand at each end and trace the sun's likely path. Check the view again in morning and afternoon, then imagine the lower winter sun. If rotating the greenhouse creates a narrow door approach, inaccessible gutter or weaker base, choose the practical alignment. Orientation improves a good site; it does not rescue a bad one.

Compare orientation with the clearance needed around the greenhouse and the space occupied by nearby trees. A useful seasonal alignment still needs a safe and maintainable site.