Sun versus Shade – Landscape Guide for proper plant choices
What amount of sun is full sun, part sun or partial shade? And how can knowing these specifications guide plant choices?
Each landscape plant has a preferred range of sun exposure. All shrubs, trees and perennials need sunlight. And it is often more than one would think. But each plant has specific sunlight preferences relating to the quantity of light, the quality of light, and the time of day it receives that sunlight exposure. These specific light exposure preferences are easily found with sources such as http://www.missouribotanicalgarden.org with their PlantFinder application. This source provides a detailed range of landscape specifications for virtually all ornamental landscape shrubs, trees and perennials.
The majority of landscape trees, shrubs and perennials prefer over six hours of full sunlight. This is considered a full sun preference. Within the full sun plant category, there are many nuances that are less easily understood. For example, many Hydrangea varieties are listed as a full sun plant. However, Hydrangea does not like hot, late day sun. Therefore, Hydrangea should be located where they get good morning sunlight into early afternoon. That would be on the east side of buildings or larger shrub and tree groupings.
Few landscape plants are truly adapted to blazing full sun throughout the entire day. Mediterranean plants like roses, Hypericum, lavender and succulents all tolerant full, hot, all day full sun. They are also a group of plants that tend to be drought tolerant. They in fact prefer the dry soil over too much water. Thought the standard is at least six hours of sunlight, this group may be best classified as a full, full sun grouping and prefers at least 8 to 10 hours of sunlight to be healthiest. This landscape category also tends to tolerate the sandy or clay soils with little organic components.
The full sun, part shade landscape plants is a category that includes plants that prefer at least 3 hours of full sunlight. They will tolerate more if available. But this category of tree, shrub and perennial often prefers relief from late day sun or full summer hot sun. These plants will tolerate mildly filtered sunlight if direct, unimpeded sunlight is not available. But don’t expect as optimal plant health if placed in filtered light.
Part shade plants are a group thrives best in filtered sunlight. For example, a loose tree canopy above the landscape gardens will allow dappled sunlight through to give a sequence of sun and shade to each plant. These plants are the types that tend to wilt and burn easily if exposed to direct sunlight any time after morning. They are also a group of plants that tend to prefer rich, organic soils because they have evolved in the hummus of a forest floor.
The full shade plant category is by far the most limited with regard to options and choices. Not many plant families or species truly prefer full shade. At least not many that are commonly used in the ornamental horticulture and landscape trades. We struggle to find plant options when a garden is especially shady. And often those garden tend to be dry in the urban and sub-urban landscape posing yet another level to the plant choice challenge. Plants like Rhododendron are often thought of as full shade plants, but that is a misconception. The plant will tolerate full shade, but it will not be as healthy and grow as well as it would in a part shade setting.
Landscape plants and plantings have preferences, but will often tolerate a little less or a little more sunlight than generally specified. They may not grow as well, but sometimes we just have to put a certain plant in a certain location because we love it there. This means we may need to water the plant and fertilize it more, take a little extra care. But don’t be afraid to try and to learn. That process is the joy of landscaping, the journey not the desitnation.