By Jenny Rose Carey
Book excerpt and photos courtesy of Timber Press
By its nature, shade shifts daily and seasonally. The number of hours of shade, the time of day that it occurs, and the intensity of the light falling on a garden are the major factors used to describe types of shade. Shade definitions can be made objective by using light meters to record the number of hours of sunlight a garden receives, but this is unnecessary for the home gardener. I prefer to use an observational approach to assess shade levels.
Generally speaking, full shade areas of the garden receive fewer than two hours of light, while an area in part shade receives between two and six hours of sunlight and is shaded for the rest of the day. For comparison, a garden in full sun receives direct sunlight for more than six hours a day.
It is helpful, however, to be specific about shade conditions in our gardens, as this allows us to make intelligent plant choices. The following categories can be used to describe garden shade more accurately.
A multilayered tree canopy provides full shade to the garden below.
Areas of full shade receive little direct sunlight, but some ambient light will reach plants by being bounced around and reflected off nearby surfaces. Such areas are often found on the darker side of houses, walls, or buildings, under coniferous trees, and beside dense hedges.
In full shade, plants grow steadily but slowly. They tend to flower less profusely than they would with more light, but the individual flowers last longer as temperatures are lower. Shade-loving plants tend to increase vegetatively, often by runners, called stolons. This is a type of asexual reproduction that produces a patch of plants that grows and spreads steadily out from the parent plant.
The darkest areas of full shade are described as deep shade, and they receive almost no direct sunlight. These areas of low light intensity are often coupled with dry soil, so plants have to be carefully selected to suit these conditions.
This partly shaded suburban garden, enclosed by trees and shrubs as well as by the solid walls of a house, has a colorful and exciting selection of plants.
An area in part shade is shaded for a portion of the day and receives between two and six hours of sunlight. This type of shade is the most common in the garden. Part shade can occur under or beside trees and shrubs, or next to hedges, walls, fences, and other garden structures.
The classification of part shade is elusive because it has so many variables. The shade-providing object, the direction of the sunlight with respect to the shade producer, and the intensity of the shade all affect what classification of part shade a garden receives.
Solid walls and other built structures are uniform barriers that block light from one direction. Plants growing near walls are shaded on one side, but not necessarily on others. Additional light may reach plants from above if they are open to the sky. Trees or other organic objects provide irregular shade. Those under the tree canopy are in dappled shade. Plants at the edge of the canopy receive more light, but are still shaded by the tree for part of the day.
Part shade can also be described by the time of day that an area is shaded—morning or afternoon. If any of these shaded situations receives additional indirect light, they can also be qualified as bright shade (for example, bright afternoon shade). All of the following descriptions are categories of part shade that can be used to more accurately describe specific garden shade conditions.
The site around the perimeter of a deciduous woodland is where you will find edge shade. In a home garden, it can even be found around individual trees, typically below the perimeter of the tree canopy. Edge shade provides some of the best growing conditions in the garden. It is an ideal situation because the light that reaches the plants is sufficient for growth and flowering, but there is enough shade so that plants do not burn during hot summer days.
Dappled shade is a type of part shade provided by trees, especially deciduous ones. The size of the leaves and the height and extent of the canopy influence the amount of light that reaches the ground. Trees with a higher canopy or smaller leaves allow more light to the ground below, while a low canopy and large leaves provide a more dense shade.
The tree leaves block much of the sun's light but do not form a complete cover, allowing areas of sun to reach the ground below in a constantly moving pattern. As trees shift in the wind and the sun passes overhead, the "puddles" of light move and change in shape. Many shade-loving plants were originally from wooded areas, so they do best in dappled shade. Plants in this type of shade can receive significant light but it is unpredictable and highly seasonal.
An area in bright shade is near reflective objects that bounce light around. Bright shade might be found near lakes, ponds, or other water features. In urban gardens, bright shade is often located near windows and white or light-colored walls. The amount of light that reaches these areas may vary considerably according to the time of day and the season of the year. There is a wider range of plants that can be grown in bright shade than in full shade due to the increased light intensity.
Trees and shrubs shelter this garden from the heat of the late afternoon sun.
Morning and afternoon shade
Planting areas that are to the west of a shade producer are in morning shade. These areas stay cool in the mornings but heat up in the hot rays of afternoon sun.
Plants that benefit from morning shade are those that bloom early in the year, as their delicate flower buds need to warm up gradually after a frosty night. Plants such as Rhododendron, Magnolia, and fruit trees have delicate flower buds that do well in morning shade. In summer, these west-facing plants receive the hottest sun of the day, so choose tough plants that can cope with the afternoon heat. Try drought-tolerant plants to prevent leaf desiccation.
Late day sun can easily scorch fragile leaves and flowers, so site plants that need protection from heat as well as sun in afternoon shade. The hotter your climate, the better afternoon shade is for the health of your plants. A planting bed situated to the east of a shade producer will receive morning sun and afternoon shade.
Plants such as Clematis and Lonicera are perfect on an east-facing wall, which receives afternoon shade. Shade plants that thrive in moist soil, or that tend to dry out, should also be situated in afternoon shade. Plants with large, fleshy leaves that desiccate easily, such as Rodgersia, Hosta, and Astilbe, are suited to this type of shade.
Author Bio: Jenny Rose Carey is a renowned educator, historian, and
author, and the senior director at the Pennsylvania Horticultural Society's Meadowbrook Farm in Jenkintown. She previously worked at Temple University for over a decade as director of the Ambler Arboretum. Her Victorian property, Northview, contains diverse garden spaces, including a shade garden, moss garden, and a stumpery. Jenny Rose and her gardens have been featured on the PBS series The Victory Garden, in the Wall Street Journal, the Philadelphia Inquirer, Green Scene magazine, and the Pennsylvania Gardener.
All articles are copyrighted and remain the property of the author.