Each October and November the forests and hillsides of North Carolina burst forth with swaths of red, purple, orange, copper and yellow when the trees change color. People travel from all over to catch the spectacular show in the mountains and foothills of the state. For those of us who haven’t the time or inclination to travel to the mountains, the scene in your own backyard can, with a bit of planning, be as rich and varied.
Why do leaves change from the bright green of spring and summer to the fall palette we so admire, and why is the show so spectacular here? The answer lies in a mix of science and luck.
First, the science. Chlorophyll gives leaves their green color. It absorbs sunlight, which powers photosynthesis, the chemical process that turns water and carbon dioxide into sugar. When the days get shorter, deciduous trees stop producing chlorophyll and store the sugar in the twigs and branches. This is one reason deer find your trees and shrubs so delicious in winter.
When the green of chlorophyll fades away, the other pigments present in the leaves can show their colors. Carotenoids give you orange and red, tannins give you brown. Anthocyanins are produced in fall and give you pink and purple. Each species of tree has the chemicals present in different mixtures, giving each tree its unique fall color.
Next, the luck. Climate will affect the strength of those colors. Bright sunny days and cool nights help break down chlorophyll and produce anthocyanins, bringing out the best fall colors. Stress or drought in spring and summer may cause leaves to drop early before they reach their best color. Wind and rain in autumn can knock foliage from the trees, shortening the season. An early frost destroys all the pigments except tannin, leaving only brown leaves in its wake.
Many trees available from your local nurseries provide a wide range of color in the fall season. Once you step beyond the bright scarlet of the red maple and the Bradford pear the possibilities are abundant.
Japanese maples and crape myrtles are the two groups of trees that can give you the greatest range of fall color. There are hundreds of cultivars in every size and color imaginable. The gingko tree gives the clearest yellow of all trees. For folks who don’t have room for a full size specimen, there are several dwarf cultivars available. The much-maligned sweet gum does turn beautiful colors in the fall. Try the columnar cultivar ‘Slender Silhouette’ which burns like a torch. Black gum, another native, is an incredible brilliant red. The weeping form and the contorted ‘Zydeco Twist’ do not get quite as large and can find a home in a smaller yard. The native sassafras is also a small tree and flaunts an impressive range of colors. While most of the ornamental fruit trees have only basic fall color, the Kwanzan cherry tree turns a warm gold and the purple leaf plum tree sports a good red.
Be an artist. Paint your own fall scene just outside your window. Plant a few of these trees. Tuck in some colorful flowers and shrubs and enjoy the view without leaving home.
Trees and their fall colors:
Japanese Maple (Acer palmatum) – Red, orange, yellow or purple, depending on the cultivar
Red Maple (Acer rubrum) – Green-yellow, yellow and red
Sugar Maple (Acer saccharum) – Orange-yellow
Katsura Tree (Cercidiphyllum japonicum) – Apricot-orange
Dogwood (Cornus florida and Cornus kousa) – Purplish-red to scarlet
Ginkgo (Ginkgo biloba) – Yellow
Sweet gum (Liquidambar styraciflua) – Yellow, purple or red
Black gum (Nyssa sylvatica) – Bright red
Chinese Pistachio (Pistacia chinesnsis) – Red, Orange, Gold
Kwanzan Cherry (Prunus serrulata ) – Gold
Purple Leaf Plum (Prunus cerasifera ) – Red
Sassafras (Sassafras albidum) – Yellow, orange or scarlet
Pat Brothers works at Atlantic Avenue Orchid and Garden Center in Raleigh.