If you’ve ever moved from one part of the country to another—particularly from north to south or vice versa—you may have been surprised at how different gardening was after you moved. Regional differences play an important role in the location of plants in the garden. For instance, the azalea that took almost full sun in Oyster Bay, Long Island, needs plenty of protection and shade from the elements in Louisville, Kentucky.
The reason for such differences is that the intensity of the sun increases the closer you are to the equator. Add to that basic fact the multitude of climatic influences—fog, clouds, lain, wind, and others–and you quickly realize that blanket statements concerning the type of exposure to give a plant are difficult to make.
Experience and a little common sense are your best guides in interpreting planting instructions. The instruction in this book may, for example, say to provide medium to light shade for tuberous begonias. If you live in an area that has a distinct marine influence, with frequent fog, moderate temperatures, and high humidity, you should know that the begonias could stand a great deal more sun than they could if you were living in Lubbock, Texas.
Once you get to know your own climate, and the many little climates that surround your house, the process of providing the right conditions for each plant becomes much easier.
Plants utilize the power from sun to create the food they want to be able to grow. In this sense, all plants need some light to survive. But don’t confuse light with direct sun; many plants can exist on comparatively small amounts of light that is reflected.
As light falls on the plant’s leaves, the chlorophyll (green pigment) inside the leaf uses the energy found in the light to convert water and carbon dioxide into oxygen and sugar, which, in turn, power the plant’s growth procedure. The plant receives most of its own water from beneath the surface of the land; the carbon dioxide is taken in the air enclosing the plant and processed through the pores of the leaves. This miraculous procedure is known photosynthesis, and to this day it’s not entirely understood.
Some plants are adapted to growing in shady places. These “shade fans” normally have significantly more chlorophyll than plants adapted to the sun. Their leaves are sensitive to light and able to use a modest number. But the cost they pay for this particular susceptibility is that they’re not rough enough to take direct sunlight for long. By destroying chlorophyll, the brightness of direct sun bleaches their leaves to a yellowish or gray colour.
Afterward these leaves that are bleached are not able to shield themselves from the warmth of sunlight. On days that are warm, they overheat and die, either by growing burnt spots, or by scorching in the edges.
Your competence can be substantially increased by even a cursory knowledge of how a plant works as a gardener—especially as it pertains to gardening in the shade.