Half the plants that fail in British gardens fail because they were planted in the wrong light, not because they were badly cared for. Before you buy anything, it is worth spending a single sunny day working out how much direct sun each part of your garden actually receives. The answer is almost always different from what you would guess.
What the terms actually mean
Plant labels and catalogues use a shorthand that is rarely explained. In UK horticultural practice the terms translate into hours of direct summer sunlight roughly as follows:
- Full sun — six or more hours of direct sun a day in midsummer. Think of an open south-facing border with nothing casting shade on it between mid-morning and late afternoon.
- Part shade (or partial sun) — between three and six hours of direct sun, or dappled light through a light tree canopy for much of the day.
- Full shade — fewer than three hours of direct sun. This still includes bright, open shade, such as the north side of a house with open sky above it.
- Deep or dense shade — little or no direct sun and reduced sky light too, for example under an evergreen tree or between closely spaced buildings.
Two things matter beyond the raw hours. Morning sun is cooler and gentler than afternoon sun, so a spot with four hours of morning light suits woodland plants such as hellebores (Helleborus) that would scorch in four hours of hot western sun. And "full shade" is not darkness: many superb plants, including Sarcococca confusa and hardy ferns, are adapted to it.
How aspect works in the UK
Aspect — the compass direction a border or wall faces — is the biggest single influence on light in most gardens. Because the UK sits between roughly 50° and 59° north, the sun is never directly overhead, and even in June it arcs across the southern half of the sky. That gives each aspect a distinct character:
- South-facing: sun for most of the day from spring to autumn. Warm, bright, and often dry at the base of walls. Suits Mediterranean plants, most fruit and vegetables, and sun-loving perennials.
- West-facing: shade in the morning, sun from around midday until evening. The afternoon sun is the hottest of the day, so west borders behave almost like full sun in summer. Good for plants that dislike cold morning sun on frosted growth, such as camellias (Camellia japonica).
- East-facing: sun in the morning, shade from early afternoon. Cooler overall. The classic caution is that early sun on frozen buds can damage camellia and magnolia flowers in March and April, because rapid thawing ruptures plant cells.
- North-facing: little or no direct sun for much of the year, though a north border with open sky can get early morning and late evening sun in June and July. Reliable territory for hydrangeas, ferns, Fatsia japonica and climbers such as Hydrangea anomala subsp. petiolaris.
Remember that the aspect of a border is set by what it backs onto, not the garden as a whole. A "south-facing garden" still contains a shady north-facing border along the back of the house.
The sun moves more than you think through the year
The seasonal swing in the sun's path is dramatic at UK latitudes. At the summer solstice in late June the sun rises in the north-east, climbs to about 60° above the horizon in southern England (lower in Scotland), and sets in the north-west, giving sixteen or more hours of daylight. At the winter solstice in late December it rises in the south-east, peaks at barely 12–15° above the horizon, and sets in the south-west, with under eight hours of daylight.
The practical consequences:
- A bed that basks in sun all day in July may receive no direct sun at all from November to February, because the low winter sun cannot clear fences, hedges or neighbouring houses.
- Shadows are far longer in winter. A 2 m fence that casts a 1 m shadow at midday in June can cast a shadow of 6 m or more at midday in December.
- Deciduous trees leaf up between April and May, so ground beneath them switches from bright to shaded exactly as the growing season starts. Spring bulbs such as Anemone nemorosa and Narcissus exploit that window, which is why they succeed under trees where summer perennials fail.
How to map the light in your garden
You need one clear day, ideally between April and September, and either a notebook or your phone.
- Sketch a rough plan of the garden showing the house, fences, sheds, large trees and beds.
- Starting at around 8am, walk the garden every two hours and shade in the areas in direct sun at that moment. Photographs from an upstairs window taken at the same times work even better, because you can compare them side by side later.
- Continue until early evening. Six snapshots across the day is enough.
- For each bed, add up the hours of direct sun and assign it a category: full sun, part shade, or full shade.
If you can repeat the exercise once in spring and once in midsummer, you will capture the seasonal shift too. Free sun-tracking phone apps that overlay the sun's path onto your camera view are a useful shortcut, and are particularly good for predicting winter light in a garden you have only seen in summer — helpful when viewing a new house.
Common mistakes when judging light
Assessing the garden in winter
People who move house between October and March routinely conclude their new garden is far shadier than it is. Judge from the sun's summer path, or wait and observe, before condemning a bed to shade planting.
Ignoring what casts the shade
Shade from a building is fundamentally different from shade under a tree. A north-facing border by a wall has full sky above it, cool soil and reasonable moisture — easy conditions. The ground under a mature birch or conifer is shaded and riddled with roots that strip moisture and nutrients from the soil. Dry shade under trees is the hardest planting situation in gardening, and plants sold simply as "shade tolerant" often cannot cope with it. Look for plants specifically recommended for dry shade, such as Epimedium, Geranium macrorrhizum and Iris foetidissima.
Forgetting reflected light and heat
Light-coloured walls, paving and glass bounce light and warmth into nearby beds. A part-shade bed beside a white-rendered wall can behave like a sunnier spot; a south-facing patio can push temperatures high enough to stress plants that would be fine in open ground.
Assuming the picture is permanent
Trees grow, neighbours build extensions, and hedges gain 30 cm a year. Reassess every few years, especially if established plants that once flowered well are becoming leggy and sparse — stretching towards the light is a classic symptom of increasing shade.
Matching plant-label language to your map
Once you have real numbers for each bed, translating labels becomes straightforward. This table matches common phrases to what your survey found:
| Label phrase | What it needs | Your survey result |
|---|---|---|
| "Full sun" | 6+ hours direct sun | Open south or west positions |
| "Sun or part shade" | Flexible; flowers best with more sun | 3–6+ hours, most aspects |
| "Part shade" | 3–6 hours, or dappled light; shelter from hot afternoon sun | East-facing beds, light tree canopy |
| "Full shade" | Under 3 hours; bright open shade is fine | North-facing beds with open sky |
| "Dappled shade" | Shifting light under deciduous trees, moist soil | Under open-canopied trees |
Be a little sceptical of the sunnier end of "sun or part shade" claims on plants bred and labelled for continental climates: in the relatively cool, cloudy UK, many plants tolerate — and often prefer — more sun than the same label suggests they would in southern Europe or much of the USA. Tomatoes, dahlias and most grey-leaved plants want every hour of British sun they can get.
Working with what you have
Light is the one condition you can barely change, so plan around it rather than fighting it. Reserve your sunniest ground for the plants that genuinely demand it — vegetables, fruit, lavender, roses — and treat shade as an opportunity rather than a penalty. You can also edit light at the margins: crown-lifting a tree (removing lower branches) in late winter can turn deep shade into usable dappled shade, and replacing a solid fence panel with trellis lets useful light into an east or west border. Painting a shady wall a pale colour and choosing pale, reflective paving both brighten adjacent beds noticeably. What you cannot do is make a north-facing basement courtyard grow lavender, and no amount of feeding or watering will compensate for planting in the wrong light.
Sources and further reading
- Royal Horticultural Society — plant selection advice by aspect and light level, and the RHS Find a Plant database.
- Met Office — UK sunshine duration averages and daylight data by region.
- Garden Organic — practical growing advice for siting fruit and vegetables.