Fall foliage color is produced by deciduous trees and shrubs. Up North, the spectacular fall color has long come and gone. Here in the Deep South, fall color is not as prominent, but we do see some. And it occurs much later.
Fall color begins to show up in October but occurs mostly in late November to mid-December. I’m still seeing a few trees with fall color now.
Even though fall color is not as spectacular in our climate, a few trees do color up nicely here (although this can vary tremendously from year to year).
The cherry laurel tree is a broadleaf evergreen tree.
A few of the more reliable trees for fall color include gingko (Gingko biloba, butter yellow), Chinese pistachio (Pistacia chinensis, scarlet and orange), crape myrtle (Lagerstroemia, yellow, orange, red), green ash (Fraxinus pennsylvanica, yellow), sumac (Rhus species, brilliant scarlet), Japanese maple (Acer palmatum, yellow, orange, red), swamp red maple (Acer rubrum var. drummondii, red, orange), Southern sugar maple (Acer floridanum, gold), sweetgum (Liquidambar styraciflua, burgundy, purple, orange, yellow) and Chinese fringe tree (Chionanthus retusus, brilliant gold) to name a few. A great deciduous native shrub for fall color is the Virginia willow (Itea virginica).
Why leaves drop
Plants that drop all their leaves at one time and enter a leafless, dormant state are called deciduous. In climates that experience cold winters, the leafless period for trees and shrubs is during the winter months when sub-freezing temperatures occur.
The Sweet Bay magnolia is an evergreen in the South but is deciduous in the North.
In cold climates where the ground freezes, it is difficult for plants to absorb frozen water from the soil in winter. So, trees and shrubs there tend to be deciduous due to lack of available water in winter. (Deciduous plants also occur in the tropics where plants have evolved a deciduous habit to cope with a dry season.)
In addition, it is hard to protect broad, thin leaf tissue from extreme cold. And the broad leaves of trees such as maples and oaks would catch the snow and cause branch breakage.
So, deciduous trees and shrubs with broad leaves simply shed them in fall and put their effort into keeping important buds, twigs and branches alive through the winter. Losing their foliage helps broad-leaved trees and shrubs get through cold Northern winters.
The Savannah holly is another broadleaf evergreen tree.
Why do trees like maples, elms, oaks and ashes drop their leaves down here? We don’t get tons of snow, and the ground never freezes. When trees that evolved in cold climates grow in milder climates like ours, they are still genetically programed to drop their leaves. So, species that have evolved a deciduous lifestyle retain it even when they grow in mild climates.
This can change. Plants do not stop evolving. The native sweetbay magnolia (Magnolia virginiana) comes in two forms. Up North these trees are completely deciduous. But, over time, Southern populations have evolved the ability to retain their leaves in winter and are evergreen (Magnolia virginiana var. australis).
Conifers, such as pines, firs and junipers, are about the only trees that keep their foliage during the winter in the Northern United States. When a Northern gardener or gardening book uses the term “evergreen” in reference to trees, it is generally synonymous with conifer.
In our mild winter climate, however, there are many broadleaf evergreen trees that are not conifers, including live oak (Quercus virginiana), holly (Ilex), cherry laurel (Prunus caroliniana) and Southern magnolia (Magnolia grandiflora) to name a few.
Still, deciduous trees are the backbone of our shade-tree plantings. This is because we prefer to use trees that provide welcome shady relief from the hot, intense sunlight of summer, but drop their leaves and allow the welcome warmth of the sun to shine through in the winter.
Red buckeye is a native deciduous plant.
Evergreen shrubs
When it comes to shrubs, however, deciduous plants are not at all preferred. Here in Louisiana, we have a vast selection of evergreen shrubs to choose from that retain their leaves year-round. Louisiana gardeners use these evergreen shrubs almost exclusively for landscaping. Although we accept and use deciduous trees in our landscapes, few gardeners will choose shrubs that look like “a bunch of dead sticks” during winter.
That’s a pity, because there are many excellent deciduous shrubs that can be used effectively to enhance Louisiana landscapes. Many of our outstanding native shrubs are deciduous, including red buckeye (Aesculus pavia), American beautyberry (Callicarpa americana), Virginia willow (Itea virginica), honeysuckle azalea (Rhododendron canescens) and arrowwood (Viburnum dentatum). Balking at the use of deciduous shrubs deprives landscapes of many desirable plants.
Of course, I’m not advocating that we use mostly deciduous shrubs in our landscapes. We are fortunate that our mild climate allows us to use a lot of evergreen trees, shrubs, ground covers, vines and herbaceous perennials. This helps provide a certain continuity of appearance throughout the year. But I have found that mixing some deciduous trees and shrubs into a landscape does two things.
First, I think it is desirable to have a landscape that changes its appearance with the seasons. The bare branches of deciduous trees and shrubs in the winter create a striking contrast to how the landscape looks in spring and summer. And new leaves emerging from bare branches signal the beginning of spring in a way that new growth on evergreen trees and shrubs never can.
Second, dropping its leaves creates a whole new personality for a tree or shrub. Take the crape myrtle for instance. With their canopy of filigree branches and smooth, muscular trunks, they are a work of art in the wintertime.
When all the leaves have fallen, and they are nestled snugly in beds as mulch or fill our compost piles, don’t despair at the barren branches. Instead, let’s appreciate the unique beauty of deciduous trees and shrubs during their leafless period.