What does a garden bed look like in sun and shade? It might be bright at noon but still be in the shade for most of the day. This distinction is important before starting to pick perennials, shrubs, ground cover, and flowers. Sun varies throughout the day, and small areas can have varying light levels depending on whether there is a wall, fence, tree, or building nearby. Before choosing plants for a bed, take some time to watch the garden over a period of time to understand the light variations rather than getting a quick snapshot of the light levels.
Pick one area, either a bed or a border, and observe it at various times during the day, such as early morning, mid-day, late afternoon and early evening. Make a note in a journal or make a top down sketch of the area, and indicate what parts of the bed get sun and what parts get shade. There is no need to make a pretty landscape plan or map; a basic sketch showing the border, path, fence, existing plants and some notes about where sun and shade occur will give you a clear picture of how uneven the lighting is.
Keep in mind the difference between full sun and partial sun. Some areas will get full sun in the morning and then be in the shade for the rest of the day. Some areas will be in partial shade all day. Some areas will get full sun but only for a couple of hours in the morning or afternoon. Keep track of where the light is full and where it is partial. Some plants will tolerate being in the shade beneath a tree all day while others will do better in full sun. It is worth noting that being in the shade beneath a tree is different from being in the shade beneath a building. Shade conditions may impact soil moisture, and it is worthwhile paying attention to how dry the soil gets after watering.
It is tempting to choose plants simply based on the color of the flower, the texture of the foliage, and what looks nice in the container. But once the plant goes in the ground, it may not get the light that it needs. Pay attention to the height and spread of the plant and how much space it will take up once it matures. It may look like a great choice for a sunny spot, but will it crowd out a neighboring plant and rob it of light once it grows larger?
Also pay attention to how wet or dry the soil is. An area in partial shade next to a wall may retain more moisture after watering, whereas an area in partial shade under a large tree may dry out quickly due to competition for water. Notice where moisture remains and where it dries out after watering or rain. Don’t just judge by looking at the surface of the soil; use your finger or a hand trowel to dig a bit deeper into the soil. These observations will give you additional insight into the conditions of your garden and why two areas in partial shade could be completely different for growing plants.
If possible, repeat your observations a day or two later, especially if it was cloudy when you made your initial observations. It is also worth noting that sun changes throughout the year, and deciduous trees will get much more shade once their leaves emerge. Again, your garden map doesn’t need to be perfect or even keep forever; it is meant to give you more information than guessing alone. When you can point to the full sun, partial sun, full shade, wet and dry areas of your bed, choosing where to plant becomes a much more straightforward decision.