The least concrete of the elements that go into the creation of a garden, light is also the element that can have the greatest sway over the success of the designed space. Managed correctly light renders the garden vibrantly alive, responsive to the seasonal changes in plants and colours. Get it wrong and you will have a functional space that fulfills the requirements of the brief, yet feels lifeless. Light is the magic that enlivens the garden and creates mood and atmosphere more fully than any planting or landscaping.
The most obvious consideration in devising a plan for a new garden is aspect - where does the light fall, at what time of year and at what time of day? In the northern hemisphere a south-facing is plot good for full sunshine over the longest period, east-facing less good for spring plantings (a full dose of early sun on frosted vegetation is not recommended) and north-facing even more challenging. However, even in the latter case it is unusual to find a garden which does not receive any direct sun at all - the job of the designer is to maximise the impact, even if the only spot which enjoys a daily dose of sunshine is that currently occupied by the garden shed.
The next consideration is the strength and quality of the light. The nearer to the equator you are the brighter and more intense it is, and by the time you get to the Mediterranean light can have an almost crystalline, physical presence at the height of summer. At more northerly latitudes the light is filtered through thicker layers of atmosphere and water vapour, with the resultant loss of brilliance found further south. There are compensations, though, and there is scope for gentler effects, greater subtlety and softer colours: the vibrant colours that suit the Mediterranean light look dull and muddied by comparison.
So how to manage light? If the garden is exposed too fully to light then shade will be essential, if light is in short supply it will need to be maximised by reflective surfaces and pale colours. Shade can be solid, a cool pool of dark, a retreat from heat and the brightness elsewhere, or dappled by overhead trees, speckling the ground plane and bringing movement to the scene. If you are going for deep shade, especially in hot southern situations, the addition of cooling water will bring the necessary element of movement - the sparkling droplets or surface taking the place of the dappling that is preferable where light is not always reliably bright. Even dappling can have varied quality - birches, with their loose forms and flexible twigs create a very lively carpet of light shade; more static trees bring shafts of light to ground level - with less movement but more definite puddles of illumination, glorious when they hit well-chosen plants like a spotlight. In the image a mossy path enjoys just this treatment, and paths in general benefit from some overhead canopy of vegetation.
Decide what effects you need and enjoy in a garden, and consider how best to achieve them - look out for future posts on other essential elements of design.