Choose tree varieties for fall display in your garden

Have you ever wondered why some trees turn red in the fall while others turn only yellow? Have you wanted to plant one of those beautiful red-looking trees or shrubs in your landscape but were afraid to because you may get one that doesn't turn red in the fall? Let me explain how fall color develops and then I'll answer these questions.

In the spring, as leaves emerge from the bud, sunlight hits them and activates the production of pigments inside the leaves. These pigments, anthocyanins and carotenoids among others, are responsible for the yellows, oranges, reds and purples we find in leaves.

Sunlight is also responsible for the production of chlorophyll, which is green. Usually leaves produce so much chlorophyll that the other pigments in leaves are masked, so that all you see with your naked eye is green.

The actual amount of each pigment produced in a given plant is determined, by the most part, genetically. For example, some Japanese maples have green leaves but plants produced from cuttings of bloodgood Japanese maples will always produce leaves that are red. Sometimes as summer progresses, with additional sunlight shining on bloodgood Japanese maple leaves, the red will begin to "fade" as more green chlorophyll is produced.

In the fall, as days begin to shorten and as cool temperatures begin to prevail, leaves begin the process of senescence, or dying. When this begins, chlorophyll is broken down, and what remains are the other pigments that were produced early in the spring. As the green fades, leaves begin to turn from greens to reds, oranges, yellows and purples.

Fall color also is determined genetically. Let me explain. If you buy a seedling red maple, you may get fall color that is somewhere between red and yellow, with a little orange mixed in. The color is quite variable in

seedling red maples. On any given tree you will not know what the fall color is until you actually see it in the fall. The fall color on a particular tree will not change appreciably from one fall to another.

To be assured of a particular fall color that you want, you should purchase a named variety. "Red Sunset" red maple is a named variety of red maple. Even before the leaves come out in the spring, you can be assured that the fall color will always be a bright crimson red. "Red Sunset" is a grated tree. Therefore, each tree will have the same genetic information. No matter where it is planted, it will always produce the same fall color.

Other species, such as dogwood, do not have very much variation in fall color. All of the flowering dogwoods that I am aware of will turn crimson red in the fall no matter what variety you plant. The same is true of most ornamental pears. No matter if you plant "Aristocrat," "Bradford" or "Cleveland Select," you will always get the same fall purple-red color.

Weather does play a role in the intensity or brightness of the color on any particular tree or shrub. For the brightest color display in the fall, we need to have good rainfall all spring and summer long. Then in the fall, a combination of cool temperatures and dry conditions will enhance the colors that do develop in the fall.

Here is a short list of trees and shrubs that will provide beautiful fall colors for your landscape. For crimson red colors, try burning bush, some oakleaf hydrangea, dogwood or firepower nandina. If you are looking for purple colors, try "Autumn Purple" ash or plum nandina. For oranges, use "Harbour Dwarf" nandina, standard nandina or "October Glory" maple. For an extended list of plants with particular fall colors, go to your local garden center and ask them what they would suggest.

We usually think about color in the landscape in the spring or in the summer. Now with some planning you can also provide for color in the fall.

Send your gardening and landscape questions to Paul Schnare at P.O. Box 699; Cape Girardeau, Mo. 63702-0699 or by e-mail to news@semissourian.com.