Millions of people drive countless miles on autumn weekends to see New England's concentrated palette of fall foliage. That's great, but people in Minnesota and Wisconsin, China and Korea, Germany and Sweden, and other locations in the Northern Hemisphere also can enjoy the foliage colors which often runs from September to November in their homelands. The overall peak of fall color for the greater Twin Cities area, to Northfield and Mankato, comes the first week of October into the second week. Last year the peak day was October 6.
Each year, trees, shrubs and vines turn color one after another in a predictable progression. Among the first to turn in Minnesota are the rich reds of the sumac and Virginia creeper. Then comes the green ash with golden-yellow foliage and the red maple with its brilliant red leaves. Many more species follow until we get to the midseason golden glow of the sugar maple forest and the fiery red of lone maples exposed to the Sun. The fall color season ends in November with the golden-yellow foliage of the weeping willow and European larch.
Some fall seasons are much more colorful than others as an early frost can kill the foliage; or, a warm, cloudy autumn can produce dull colors. The striking color changes that take place, as deciduous woody plants prepare to drop their leaves, are triggered by shortening days and cooler weather. Changes in color may also come about because of what we call built-in biological clocks.