Contrary to popular perception, California does change colors during autumn. While evergreen conifers may dominate portions of the state, the green leaves of many broadleaf species slowly transition from green to yellow, orange or red from September through December. In fact, because of the state’s unique combination of climate and geography, California offers some of the finest foliage-watching opportunities in the country.
Why Leaves Change Colors
Green plants derive their color from a pigment called chlorophyll. By combining chlorophyll with carbon dioxide, water and sunlight, the plants produce sugars, which form their primary food source. However, as the days become shorter and the nights become longer, trees produce less and less chlorophyll. Without chlorophyll to turn the leaves their characteristic green color, brown, yellow, orange or red colors become visible, courtesy of the other pigments and structures of the leaves. Around the same time, the leaves begin building up a layer of cells – called the abscission layer — which halts the flow of resources to and from the leaf. The abscission layer also weakens the attachment point of the leaves, allowing them to eventually fall off.
Because the leaves of different tree species have different chemical compositions and structures, they exhibit different colors during the fall. For example, most dogwood leaves turn magenta or burgundy, while hickory leaves turn a brilliant gold. Other species, such as the beautifully gaudy maples, may turn a variety of colors; a single tree may even bear leaves of many different colors. Some of the most remarkable specimens are cultivars that have been artificially selected for brilliant fall color.
Factors Influencing Color
Not all autumns are created equally. Some autumns seem to be painted with eye-popping colors, while others tend toward more muted tones. Differing environmental variables, such as temperature, windfall and precipitation, cause this year-to-year variation.
In general, cool, yet sunny, days and cold nights often elicit the finest colors that local trees have to offer. By contrast, warm autumn temperatures typically reduce the intensity of fall colors. Droughts are similarly detrimental to fall color (a particularly important variable in California), while moist soils in the fall enhance fall colors. Poor weather, such as torrential rain or high winds, often causes the trees to lose many of their leaves, which effectively shortens the duration of the fall colors.
Searching for Fall Color
Adventurous souls often enjoy taking road trips to enjoy the fall color. In most locations, timing is critical for catching the colors at their peak. Arrive a week too soon, and the colors will still be developing; arrive one week too late, and many of the trees will have jettisoned their leaves for the year. Fortunately, this is not the case for much of the Sunshine State.
California’s geography provides a unique advantage for viewing fall color. In fact, California tree lovers often have a better chance to catch peak fall colors than New Englanders do. The timing of the New England fall color change varies largely with latitude; the farther south a given location is, the later the leaves begin to change. Accordingly, each given latitude has a narrow window of peak color.
By contrast, at a given latitude, Californians can view trees at a wide range of altitudes. This variation in altitude affects the timing of the color change just as variation in latitude alters the timing of New England’s color change. This means that while standing at the bottom of the Sierra Nevada Mountains, you can see the color change progressing from the top of the tree line towards the bottom. While the entire slope is unlikely to change at the same time, some part of the slope is likely to be clad in glorious colors during a large portion of autumn.
If you want to see the best fall colors that the state has to offer, check out this list from the California Department of Parks and Recreation. You can also check out CaliforniaFallColor.com to see photos of the current colors of various locations around the state.
Planting for Fall Color
You do not have to chase fall colors to enjoy crimson, gold and blaze colors; you can grow your own colors in your yard. Many common species and cultivars produce stunning fall foliage. By planting several different varieties, you can create gorgeous fall landscapes. It is generally wise to rely heavily on native species, but you can use also use suitable exotics to incorporate colors and textures unseen in the natural landscape.
Some California natives that display good fall color include:
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Vine MapleAcer circinatum
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Mountain MapleAcer glabrum
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Big Leaf Maple Acer macrophyllum
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Quaking AspenPopulus tremuloides
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Black CottonwoodPopulus trichocarpa
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Oregon White Oak Quercus garryana
Several non-native, yet hardy species (which are unlikely to become invasive) include:
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Gingko TreeGinkgo biloba
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Pin OakQuercus palustris
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Black GumNyssa sylvatica
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Red MapleAcer rubrum
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Japanese Maple Acer palmatum
Be sure to check out this list of trees by the Arbor Day Foundation. It details nine different species that usually produce excellent fall color, are unlikely to spread and are suitable for planting in a wide variety of locations.