Sun or Shade- What Do You Have?
One question you have to answer to situate your plants correctly is how much sun or shade does the area of the garden you are planting have. It is really a difficult question unless you know what criteria to use to make that designation. I find it helpful to think of the amount of light an area gets on a continuum from full sun to deep shade. The designations most websites use of full sun, part sun or part shade and full shade does not give enough information to situate plants correctly. It don't consider the crucial question of when that sun is actually hitting the plants nor does it take into account the all important issue of how much moisture is available to the plant. For that reason we have developed our own system which we have used throughout the website.
Sun, at one end of the continuum, means direct sun for at least six hours during the hottest part of the day. In the center of our daylily field the plants get sun from sunrise to sunset with no shade from buildings or the shadow of trees. As you move along the edge of the field toward the tree line the daylilies in that area would be in shade for a couple of hours in the early morning but would still get at least six hours of direct hot sun. That area would be considered sun as well. Some plants that we would not normally consider sun lovers can do well in that environment as long as they are never allowed to dry out. We have included that information in the Growing and Maintenance Tips provided for each plant
In our display garden as the sun moves overhead there are areas that get from four to six hours of direct sun but, because of the trees surrounding the gardens, do not get the six hours necessary to be classified as sun. The crucial question is whether any of that sun occurs over the hottest part of the day from 10:30 am to 2:30. If it does we classify that area as partial sun. Many sun loving plants grow well in that environment even though they are not getting sun all day long. Many hostas that are not sun tolerant will burn in that situation even though most websites would categorize that area as part shade based just on the measurement of hours of sun.
If the area is in shade over the hottest part of the day we classify that area as partial shade. Direct sun is still hitting the plants but it may be early morning or late afternoon or both. Many plants love this environment. There is enough sun for darker foliage to colour well and for the plant to remain compact and not stretched for light. However plants will not be scorched by the hot sun over the noon hour. Plants will not dry out as quickly so can survive brief periods of drought better.
If the area gets less than four hours of direct sun either in the morning or the late afternoon this would be classified as shade. This often happens in areas where buildings, fences or dense trees shade the area for most of the day. Many of the blue leaved hostas like this situation and will hold their blue colour better. Many of the native woodland plants also like this environment. Finding the right plants for this situation can often be a bit of trial and error. If there is not sufficient light flowering will be sparse and the plants will become too leggy.
Dappled Light or Filtered Shade
When you have trees on your property there will be areas under those trees where there is a mixture of sun and shade. Some light penetrates through the foliage and the area is usually cooler. The amount of light there will depend on the type of tree and whether it has been limbed up to allow more light to penetrate. In these conditions many woodland plants like Ginger (Asarum) and Jack in the Pulpit (Arisaema) whose native habitat is the forest floor do very well. If the trees are deciduous these plants will get lots of light in the spring when they are actively growing. In this environment the other consideration is competition from tree roots. The tree roots strangle many plants, taking all the available nutrients. A hosta in a container would grow well with the available light but may be strangled by tree roots if it is in the ground. A groundcover like Sweet Woodruff (Galium odoratum), which only needs a couple of inches of soil, will grow well.
There are very few plants that will thrive in very deep shade. Spring ephemerals like Trilliums will grow under deciduous trees because they get lots of light in the spring when they need it. Lamiastrum will carpet the ground even in dense shade. Native Plants like Baneberry are also good candidates but often the best solution is to use containers which can be rotated in and out to provide colour in very dark sites.