In response to garden center customers' interest in pollinator plants for shaded gardens, I collaborated with my colleagues to write this blog post of recommended plants. But as I was thinking about it a little more, another question that I often hear from other gardeners arose: what is shade? More specifically, what are the differences between full sun, part sun, part shade, and full shade? And how can you observe these differences in your garden so that you can make appropriate choices? Here is a simple method:
Be prepared to spend a sunny day at home in order to observe how the sunlight falls across your garden throughout the day. At 2-hour intervals for a total of 4 observation times, take notes on how the sunlight falls at the following approximate times: 10am, 12pm, 2pm, and 4pm. Since we're currently in Eastern Daylight time, solar noon occurs at approximately 1pm, so the period of most intense sunlight occurs from 10am-4pm.
Be sure to look for microclimates by observing multiple locations in your garden. A garden bed next to a South-facing wall is likely to be a few degrees warmer and a little drier whereas an installation to the North-east of a large hedge may remain cooler and more damp.
If you observe that a given spot is sunny all 4 times from 10am-4pm, that spot receives full sun. For our geographic area, full sun is described as 6 or more hours of direct sunlight.
If you observe that a given spot is sunny 3 out of 4 times, that spot receives part sun. (Between 4 and 6 hours of direct sunlight.)
...2 out of 4 times, part shade. (Between 2 and 4 hours of direct sunlight.)
...1 (or 0) times, full shade. (Less than 2 hours of direct sunlight.)
One of DC's best-kept secrets for garden inspiration and how to make the best use whatever space you've got, sun or shade, is the Smithsonian Ripley Garden.
The Virginia strawberry I planted as a groundcover in my shaded front yard is currently in bloom. Soon, it will be covered in petite, flavorful berries.