Excerpt
In nature as well as in gardens, shade is never a constant: it depends on a fluctuating framework of trees and shrubs — the bones of the garden. This shade-giving framework changes steadily and thus alters the location, timing, and intensity of the shade it provides. In time, gardeners may have too much shade. The remedies are simple. The most obvious and frequent solution is to cut down trees or tall shrubs or to resort to "limbing up" the offending trees. Some trees and most tall shrubs need periodic pruning for best performance anyway, so this pruning can be performed with ultimate shade requisites in mind. As trees and shrubs grow older, eventually they die and must be removed or storms topple them. Gardeners should be aware that their shade might disappear in spots. With the passing of time, all gardens change.
For gardens without shade-giving trees, shade may be created by erecting shade houses or vine-covered pergolas. These can be rudimentary structures or they can take on a more architectural tone. As decorative, functional, and useful as they may be, these structures can never replace the living beauty of shade-giving trees and shrubs in a woodland garden.
The wild woodland floor is made up of the byproducts of tree growth and organic life in the woods. Such woodland soil is to die for but rarely, if ever, is such "gardener's gold" available. In many residential areas, the suburban landscape is so thoroughly disturbed that gardeners must "create" their own soil.
To take available soil and improve it to attain good physical structure and openness (a condition sometimes referred to as good tilth) is timeconsuming, labor-intensive, and often expensive. Adding organic matter to natural clay or sandy soils is essential. Among the types of organic matter suitable for gardens are ground bark, coarse sphagnum peat, or ground natural waste, such as peanut hulls or corncobs. Ground tree clippings can be obtained cheaply and are sometimes free for the taking. Gardeners can collect pine needles, leaves, or other natural waste; once composted, these materials make fine soil amendments. There is nothing better than adding humus from a gardener's compost pile.
Knowing the soil is essential to making a garden. Many county extension offices of the United States Department of Agriculture (USDA) provide a soil analysis service either free or for a nominal charge. Soils can be acid, alkaline, or neutral, which level is indicated by the pH number. Neutral soil is represented by pH 7. Readings above 7 indicate increasingly alkaline conditions, and those below 7 indicate increasingly acid conditions. Inexpensive pH meters are available at nurseries, so gardeners can do their own pH testing.
Many shade perennials with large leaves require considerable available and constant amounts of water in the soil. These conditions can be accomplished by adding organic matter to the soil. Some soils can hold too