Shade is easy to recognise and rather harder to describe accurately. The ground beneath a mature tree, a north-facing border and a bed which receives three hours of morning sun may all be called shady, although the light reaching each of them is quite different.

The familiar terms full shade, part shade, dappled shade and deep shade are useful because they give us a common language, but they should never be treated as exact measurements. The time at which sunlight arrives, the brightness of the surrounding space, the object casting the shadow and the season can all alter what a plant actually experiences.

As a practical starting point, full shade receives less than about two hours of direct sun, while part shade generally receives between two and six hours. Deep shade sits at the darkest end of the scale, with almost no direct sunlight, while dappled shade describes the broken, moving light which filters through an open canopy. Those definitions become much more useful once the character of the site is added to them.

For the wider questions of soil, moisture, planting and maintenance, see our complete guide to shade gardening in Ireland. Here the concern is the light itself: what the different shade terms mean and how to decide which one describes your garden.

Shade is a moving condition

A shaded area is rarely equally dark from morning until evening. The sun changes position continuously, shadows lengthen and shorten, and light may reach the same border from several directions during the course of a day. A label based on one brief look at the garden can therefore be misleading.

A border on the eastern side of a house may receive direct morning sun and remain shaded for the rest of the day. On the western side, the pattern is reversed, with shade in the morning followed by stronger light later. Both could reasonably be described as part shade, but they do not provide identical growing conditions.

Trees make the picture still more variable. Light passing through an open deciduous canopy appears in small moving patches which travel across the ground as leaves and branches shift. Beneath a dense evergreen, by contrast, the shadow may alter little even though the position of the sun has changed considerably.

This is why the number of hours of sun is useful without being sufficient. A more informative description includes when that sun arrives and what the garden looks like during the hours when direct sunlight is absent.

What is full shade?

Full shade is generally a position receiving very little direct sunlight during the growing season, commonly less than about two hours a day. It does not mean complete darkness. Plants still receive indirect or reflected light from the sky and surrounding surfaces, and the amount of this background light can make one full-shade position considerably brighter than another.

The north side of a house provides a good example. A border may receive little or no direct sunlight yet remain open to a broad expanse of sky overhead. On a bright day it can feel surprisingly luminous. A narrow passage between two buildings may also receive no direct sun, but because much less sky is visible the actual light level at plant height can be markedly lower.

Shade from a solid building is also different from shade beneath trees. A wall blocks sunlight from one direction but does not form a roof over the border, so light can still arrive freely from above. Under a tree, the canopy intercepts some of that overhead light as well.

Full shade is therefore best understood as a shortage of direct sunlight rather than an absence of useful light altogether.

What is deep shade?

Deep shade is the darkest end of full shade. Direct sunlight is almost entirely absent and relatively little indirect light reaches the ground either. It is commonly found beneath dense evergreen trees and shrubs, beside thick evergreen hedges, beneath low spreading branches or in narrow spaces enclosed by several structures.

Look upwards when judging it. If a plant has almost no clear view of the sky because foliage, walls or buildings surround it, the position is more restrictive than an open border which happens not to receive direct sun.

Deep shade is often associated with dry ground beneath established trees because the canopy intercepts rainfall and roots compete for the moisture which does reach the soil. The two conditions should not be confused, however. Deep shade describes light, not moisture. A dark position can be dry, moist or badly drained, and those differences will later be just as important as the shade itself.

Very dark ground also tends to place greater emphasis on foliage. Flowering is usually less generous as light becomes severely restricted, so evergreen structure, leaf texture and ground cover often become more useful than trying to force a succession of plants which need brighter conditions to flower well.

What is part shade?

Part shade, sometimes called partial shade, describes ground which receives direct sunlight for part of the day and is shaded for the remainder. A working range of roughly two to six hours of direct sun is useful, although the quality of those hours matters as much as the total.

Three hours of gentle morning light are not equivalent to three hours of stronger late-afternoon sun. A plant on an east-facing boundary may enjoy the first situation, whereas the same plant beside a west-facing wall can experience much warmer conditions before the sun disappears.

Part shade is consequently a broad category. It includes borders at the edges of tree canopies, positions beside buildings, areas temporarily shaded by shrubs and places which move in and out of direct sunlight as the sun crosses the garden.

Of all the common shade types, this is often the one with the widest planting possibilities because there is enough direct light to support good growth and flowering while some protection remains from prolonged exposure. That does not make every part-shade position equally suitable. The timing of the light and the conditions below ground still have to be considered.

What is dappled shade?

Dappled shade describes a pattern rather than a fixed number of hours. It occurs when sunlight filters intermittently through gaps in a canopy, producing a constantly changing mixture of light and shadow on the ground.

Deciduous trees are the usual source. A high, airy canopy with relatively small leaves allows a considerable amount of light through, while a lower or denser canopy can produce much heavier dappled shade. Two trees standing beside one another may therefore create quite different conditions beneath them.

Dappled shade is broadly a form of part shade, but the distinction is useful. A border receiving three uninterrupted hours of morning sun is exposed to light in a different way from a border receiving hundreds of brief flashes of sunlight throughout the day, even if their total exposure were similar.

There is also a visual difference. The shifting light brings out changes in leaf surface and texture particularly well. Broad foliage alternately brightens and recedes as the sun moves, while finely divided fern fronds catch small patches of light along their edges. This is one reason woodland-style planting often looks especially convincing beneath a light tree canopy.

Bright shade can still receive no direct sun

It is sometimes useful to add the term bright shade or light shade when one of the main categories does not tell the whole story. A position may receive no direct sunlight and technically fall within full shade, yet remain bright because it is completely open to the sky or receives reflected light from pale walls and paving.

This is quite different from deep shade beneath a dense evergreen canopy. The two sites may record the same number of hours of direct sunlight, namely none, while offering very different amounts of usable light during the rest of the day.

The distinction is particularly helpful around buildings. An open north-facing border can be a good deal brighter than its aspect suggests, whereas the base of the same wall beneath an overhanging tree may be considerably darker. The compass direction has not changed; the amount of sky visible to the plants has.

The same garden changes through the seasons

A shade assessment made in midsummer is not a permanent description of the garden. The angle of the sun changes through the year, and deciduous trees alter the amount of light reaching the ground dramatically as their leaves appear and fall.

Beneath a deciduous canopy, winter and early spring can be surprisingly bright. Bulbs and early perennials take advantage of this period, making much of their growth before the leaves overhead have fully expanded. By midsummer the same piece of ground can be in substantial shade for most of the day.

Evergreen trees and hedges create a more continuous shadow, although even here the changing height and angle of the sun alter where that shadow falls. Buildings do the same. A border completely shaded by a wall in winter may receive some direct light when the summer sun is much higher.

For important planting areas, one observation in one month is therefore not enough. The garden does not have to be mapped every week, but seeing the site in spring and again around midsummer will prevent many mistaken assumptions.

How to assess the shade in your garden

A simple observational approach is usually enough. Choose a reasonably bright day and look at the garden several times rather than standing in it once and deciding that it is shaded.

• Begin in the morning: note which areas receive direct sunlight and roughly when it reaches them.
• Look again around midday: watch whether earlier sun has disappeared, whether shadows have moved and whether tree canopies are producing broken light.
• Return in late afternoon: west-facing ground which was dark earlier may now be receiving its strongest light.
• Look upwards: decide whether the position is open to the sky, partly enclosed by branches or almost completely covered.
• Identify the cause: a wall, deciduous tree, evergreen hedge and neighbouring building each create a different sort of shade.
• Repeat in another season: this matters particularly where deciduous trees or the changing angle of the sun have a strong influence.

Exact measurements are rarely necessary in a home garden. The purpose is to understand the pattern well enough to make sensible planting decisions. A gardener who knows that a border receives two hours of morning sun followed by bright open shade has more useful information than one who simply writes “shady border” on a plan.

Describe the site in a little more detail

Once the main category has been chosen, add one or two qualifications. They take only a few words but make the description much more useful.

For example:

• Full shade beside a north-facing wall, but open to bright sky.
• Deep shade beneath a dense evergreen canopy.
• Part shade with morning sun and shade after lunchtime.
• Part shade with stronger late-afternoon sun.
• Dappled shade beneath a high deciduous tree, much brighter in spring.
• Deep shade beneath an evergreen hedge with a dry, root-filled soil.

The final example includes moisture and roots because they are important to the site, but they are not part of the definition of shade. Keeping those ideas separate prevents the common assumption that all deep shade must be dry or that all dappled shade must be moist.

Use the shade label as a starting point for plant choice

Plant labels often reduce light requirements to a small sun or shade symbol, which is useful for screening out obviously unsuitable choices but does not settle the question. Plants respond to a range of conditions, and moisture, soil and root competition may decide whether a theoretically suitable plant actually succeeds.

Fatsia japonica, for example, is valuable in shade because its large evergreen leaves maintain a strong presence where flowering may be limited. Pachysandra terminalis can make a useful evergreen ground layer in low light, while Polystichum setiferum gives a much finer texture. Yet none of these plants should be selected by light alone; the root zone and available moisture still matter.

In brighter part or dappled shade, plants such as Brunnera macrophylla ‘Jack Frost’ and Hosta ‘Gold Standard’ show why the exact character of the site is worth understanding. Their foliage can be particularly effective in subdued light, but a position beneath thirsty tree roots is very different from cool, moisture-retentive shade beside a wall.

Epimedium × perralchicum ‘Fröhnleiten’ is useful where shade is combined with a more competitive root zone, while Hydrangea petiolaris illustrates another distinction altogether: a shaded wall can still provide enough open-sky light for a substantial climber, even though direct sun is limited.

These examples are not intended as a plant list. Once the light pattern has been identified, the next step is to combine it with soil, moisture, mature size and garden use. Our guide to choosing plants for your shade conditions covers that decision in detail.

Frequently asked questions

Is full shade the same as deep shade?

No. Full shade generally means very little direct sunlight, but the position may still receive plenty of indirect or reflected light. Deep shade describes the darkest part of that range, where both direct sunlight and background light are severely restricted.

Does full shade mean no light at all?

No. Green plants still need light. A full-shade border normally receives ambient light from the sky or reflected light from surrounding surfaces even though direct sunlight reaches it rarely or not at all. A position approaching complete darkness is not a useful planting site merely because it has been labelled shade.

Is dappled shade a type of part shade?

Broadly, yes. Part shade describes a position which is shaded for some of the day, while dappled shade describes the broken pattern of light created most commonly by a tree canopy. The distinction is helpful because intermittent filtered light affects a garden differently from several continuous hours of direct sun.

Is a north-facing garden always in deep shade?

No. Aspect is only one influence. A north-facing garden which is wide and open to the sky can remain quite bright, while one enclosed by buildings, trees or evergreen hedges may be much darker. The actual movement and intensity of light should be observed before the shade type is decided.

How many hours of sun count as part shade?

Roughly two to six hours of direct sunlight a day is a useful working definition, but it should not be treated as a rigid rule. The time of day, intensity of the light, season and brightness during the remaining hours all affect the character of the site.

Can the shade type change during the year?

Very often. Deciduous trees may leave the ground comparatively bright in winter and early spring before producing substantial summer shade. The changing height of the sun also alters the shadows cast by buildings, walls and fences, so an important planting area is best observed in more than one season.

The most useful shade label is therefore not necessarily the most precise-sounding one. It is the description which tells you what the plant will actually experience. Once the difference between full, part, dappled and deep shade is understood, the garden becomes much easier to read, and later decisions about soil, moisture and plant choice can be made on firmer ground.