Growing healthy plants in shady places is something many of us need and want to do. To do this well we first need to identify the type of shade an area has, as well as identifying the degree of shade that a plant requires or will tolerate. Very few plants will thrive where shade is very dense particularly when coupled with a dry and impoverished soil to grow in.
Shade is often a subjective term and not all shade is created equal. The Oxford Paperback Dictionary & Thesaurus
All plants need some form of light to process their food, through photosynthesis, some plants need more, some less.
Defining shade tolerance in a plant and shade levels in a planting location allows us to determine a successful position for a plant to grow. Which in principle is simple in practice it is obvious that it is not. Where you live in the world will also determine again how intense the sunlight is, southerly latitudes have more intense light. Weather is a further factor cloud cover also screens light intensity.
So how can we define shade in rough terms in our own gardens?
The standard definitions of shade are:
- Light shade: A site that is open to the sky, but screened from direct sunlight by an obstacle, such as a high wall or group of trees.
- Partial shade: A site receiving sunlight for 2 or 3 hours either in early morning or late evening. No midday sun as it supplies considerably more light.
- Dappled or Moderate shade: Mainly reflected or diffused light, for example through tree canopies. Trees may have a trunk cleared of low branches that allows light to access beneath at certain times of day.
- Full or Deep shade: Usually under dense deciduous or evergreen trees, e.g. beech, conifer hedges or overgrown shrubberies. Also beneath decks and low raised structure in the garden. Less than 3 hours of direct sunlight each day, with filtered sunlight during the rest of the day. Deep shade does not mean no sun. There aren’t many plants, that can survive in the dark!
Other sources discuss Partial and Full sun:
- Partial sun: A site with partial sun differs from partial shade in that it receives more light, between 4-6 hours of sun a day, and can include midday and afternoon sun
- Full Sun: A site with full sun receives 6 or more hours of sunlight. This doesn’t have to be continuous and could be 3 hours in the morning, shade at midday and 4 hours in the afternoon as long as the light is direct light.
For new garden sites I am designing I use a great little phone app called Sun Seeker – I use lite which is free. Originally designed for Filmmakers/Photographers it shows your position (or that of the phone), the sun’s rising/setting positions and the route it travels through the day. This helps you see where your shady spots might be. I also use SketchUp to 3D model my sites and it’s locator functionality allows me to see easily how feature might affect the light in the garden.
A final alternative, demonstrated by Alan Titchmarsh in a recent Love Your Garden episode is to sit in a deck chair and watch the sun’s movement around your garden for a day noting how much each area gets and when.