Why Leaves Change Color - Fact Sheet, autumn colors 

United States 

Department of 

Agriculture 

Forest Service 

Northeastern Area 

Fact Sheet 

SP-01-01 

Autumn in the Northeast and Midwest can be a spectacular 

season of bright blue skies, cool temperatures, and brilliant 

leaf color. Over 170 million acres of land in the twenty 

Northeastern states are covered with trees and forests, 

giving us plenty of opportunity to enjoy fall color. These 

forests are a mix of conifers (cone-bearing trees such as 

pine, spruce, and hemlock) and deciduous trees (trees that 

lose their leaves each year such as maple, oak, birch, and 

aspen.) 

You may have noticed that leaf color varies every year. Leaf 

color is most spectacular when the right combination of 

factors are present. Scientists don't fully understand all of 

the complicated interactions that cause the best display of 

leaf color, but they do know that leaf pigments, length of 

night, the type of tree, genetic variation, and the weather 

all play a role. 

Where Do Leaves Get Their Autumn Colors? 

Tree and plant leaves contain pigments that give them their color. Three pigments are 

involved in fall color: 

· Chlorophyll — gives leaves their green color. 

· Carotenoids — provide the yellow, orange, and brown colors 

Anthocyanins — give the red and purple colors. In contrast to the other two pigments, 

· anthocyanins are produced in the autumn, in response to bright light and excess plant 

sugars in the leaf cells. 

During the growing season, most tree leaves are green because they are full of chlorophyll. 

Plants use chlorophyll to capture sunlight for photosynthesis, the process that enables them 

to manufacture their own food. The amount of chlorophyll is so high during the summer that 

the green color masks all other pigments present in the leaf. As the days grow shorter in the 

fall, chlorophyll production slows down and eventually stops. The carotenoids and 

anthocyanins that are present in the leaf then become visible. 

http://na.fs.fed.us/spfo/pubs/fs/colors/colors.htm (1 of 3)11/22/2004 10:35:03 AM 
Why Leaves Change Color - Fact Sheet, autumn colors 

Do Different Kinds of Trees Turn Different Colors? 

Certain colors of leaves are characteristic of particular species of trees. 

· Oaks turn red, brown, or russet; 

· Hickories turn golden bronze; 

· Dogwood turns purplish red; 

· Beech turns light tan; 

· Red maple turns brilliant scarlet; 

· Sugar maple turns orange-red; 

· Black maple turns glowing yellow; 

· Sourwood and black tupelo turn crimson; 

Aspen, birch, and yellow-poplar turn golden · yellow. 

Leaves of some species such as the elms simply shrivel up and fall off, exhibiting little color 

other than brown. 

The timing of the color change also varies by 

species. Sourwood in southern forests can 

become vividly colorful in late summer while all 

other species are still green. Oaks put on their 

colors long after other species have already shed 

their leaves. These differences in timing among 

species seem to be genetically inherited. The 

timing of color change for certain species 

appears to be consistent regardless of local 

weather patterns or changes in latitude 

Why Are Some Autumns More Colorful? 

Temperature and moisture greatly influence autumn color. Since each of these vary greatly, 

no two autumns are ever alike. A succession of warm, sunny days and cool, but not freezing 

nights seems to bring about the most spectacular color displays. Since carotenoids are 

always present in leaves, yellow and gold colors are fairly constant from year to year. In 

order for the brilliant scarlet, purple and crimson colors to develop, bright sunlight in the 

early fall is needed. Bright sunny days increases food production in trees and plants. These 

sugars are trapped in the leaves spurring the production of anthocyanin pigments, providing 

the red tints to fall foliage. 

The amount of moisture in the soil also affects autumn color. A late spring, or a severe 

summer drought, can delay the onset of fall color by a few weeks. A warm period during fall 

lowers the intensity of autumn color. Trees defoliated by insects during the growing season 

may also show less fall color. 

http://na.fs.fed.us/spfo/pubs/fs/colors/colors.htm (2 of 3)11/22/2004 10:35:03 AM 
Why Leaves Change Color - Fact Sheet, autumn colors 

Why Do Leaves Fall? 

Deciduous trees drop their leaves in order to survive the harsh conditions of winter. Stems, 

twigs, and buds are equipped to survive extreme cold. Tender leaf tissues however, would 

freeze in winter, so plants must either protect their leaves or shed them. 

The evergreens — pines, spruces, and hemlocks – are able to survive winter because they 

have developed a way to protect their foliage. Their needle-like or scale-like foliage is 

covered with a heavy wax coating and the fluid inside their cells contains substances that 

resist freezing. 

Fallen leaves are not wasted, they decompose and restock the soil with nutrients. The rich 

layer of decomposing leaves protects the roots of other plants on the forest floor and absorbs 

and holds rainfall. Imitating nature by mulching with shredded leaves provides similar 

benefits for trees and shrubs in the home landscape. 

Where and When is the Best Time to See Fall Color? 

Generally, peak colors develop in late September for the 

Northern States and can extend from October through early 

November in the Mid-Atlantic and Southern Midwestern states. 

The National Forest System lands, State Forest and county 

lands provide ample opportunities for driving, hiking, and 

recreating in areas surrounded by fall color. For updates on fall 

color as well as scenic drives, call the USDA Forest Service’s 

Fall Color Hotline: 1-800-354-4595. 

For more information: 

— Autumn Colors - How Leaves Change Colors 

— Why Leaves Change Color 

On-line Publications and Other Info. |St. Paul Field Office 

http://na.fs.fed.us/spfo/pubs/fs/colors/colors.htm (3 of 3)11/22/2004 10:35:03 AM