There are very, very few plants that can thrive in any light conditions. Typically, they favor either full sun or mostly shade with a varying tolerance for doses of the opposite. The gardener needs to carefully asses and consider the available light in his outdoor space before buying plants. This is especially important when purchasing perennials, which can cost more because they return in the next growing season. If you don’t know a plant’s needs, it probably won’t thrive and it may not even live. Make sure you know the proper place for your perennials.
Sunlight will naturally vary to some during the course of a day or over the span of a year due to cloudy days and other weather patterns. However, a gardener can usually determine the average exposure a particular area receives without much trouble.
- Full sun. Full sun is defined as 6 or more hours of sun exposure in a day. This includes open areas of lawn and areas not blocked by walls or structure. Perennial for full sun include daylilies, sedum and salvia.
- Partial sun or partial shade. Used interchangeably, this category receives anywhere from 3 to 6 hours of sun exposure. If it is on the lower end of the range, we typically say “partial shade” and the higher end is referred to as “partial sun”. Partial sun/shade perennials include holly fern, ajuga and some hostas.
- Dappled sun/shade. An area of dappled sun or shade is usually under the cover of high deciduous trees, as in a wooded area or beneath an established oak. It gets several hours sun but in a filtered way.
- Full shade. Receiving less than 3 hours of direct sun exposure in a day, a full shade area is limited in what light it receives. The sun may be somewhat blocked by your home or thickly wooded. Some hostas and the painted fern like full shade.
You can purchase color changing exposure meters to help measure your available light. They can cost just a few dollars for a simple device or quite a bit more for a fancy digital version. You can also map your garden yourself for free.
Just make a rough sketch of your garden on paper and check the light at several intervals during the day. Use a pencil to shade in areas where the garden is no longer getting direct sun. Check at least four times: early morning, midmorning, early afternoon and late afternoon. More frequent checks will give you better results.
Once you know how much sun your planting beds are getting, you can begin to choose perennials to fill them. Look at the tags on plants or the descriptions if you are ordering online. Many will give a range, like “full sun to partial”. This means the plant has a preference for the first but will tolerate the second (keep in mind, full sun perennial will need a little more water than shade).
Putting your perennials in the right place will help you grow the lush garden you want.