Homeowners should know what direction their home faces before planting anything. My house faces almost directly south, so if I stand in the street looking at it I’m looking north and south is behind me. West is to the left and east to the right. My lot is bordered by forest on the north, east, and west sides, so some part of it is always in shade. Knowing these things allows me to place any plant accurately according to its light requirements.
The sun sets in the west, which means the eastern side of my yard gets hot afternoon sun. Since the sun rises in the east, the western side of my yard gets the cool morning sun. If I were laying out a vegetable garden I’d lay it out so the plant rows went east to west. Doing so would mean the plants would get morning, mid day, and afternoon sunlight and would be growing in full sun.
Because of the blocking action of the trees, in my yard the sun shines brightest directly opposite of where it rises or sets.
Plants that need partial sun usually do well when shaded in the morning but need hot afternoon sun, so I’d plant them on the eastern, afternoon sun side of my yard. If the plant was a delphinium, iris, daylily, sedum, or any other sun lover, this would be the best place for it.
For plants that need partial shade, it’s the reverse. These like cool morning sun and may shrivel in the extreme afternoon heat, so I’d plant them on the western, morning sun side of my yard. Hosta, columbine, creeping phlox, ferns, impatiens, and any other plant that dislikes hot afternoon sun would do well.
When a plant is said to “prefer shade,” this really means that it dislikes hot sun but would happily take 8 hours of cooler morning sun if it were possible. It is more accurate to say that these plants actually tolerate shade but still need some morning sun, or at least bright light.
In my experience there are very few plants that actually need “full sun.” Even those that supposedly do will often do well in partial shade provided they get some afternoon sun. I once grew tomatoes for people in a garden that received only 2 hours of direct sunlight each afternoon. They weren’t going to the farmers market each Saturday with tomatoes to sell, but they had a fairly good harvest.
When it comes to sun exposure the important things to remember are:
Full sun means 6-8 hours of direct sun per day.
Partial sun means 3-6 hours of afternoon sun per day.
Partial shade means 3-6 hours of morning sun per day.
Shade means filtered light or dappled sunlight under trees or taller bushes. The light in such areas is cool and quite bright, though little or no sunshine ever reaches the ground. The soil also stays quite cool and is usually under a mulch of leaves. This is where plants like lady’s slipper, trillium, sweet woodruff, mountain laurel, shad bush, hawthorn, flowering raspberry, and many other understory plants grow naturally.