Even though we are reaching the low 90s and high 80s across the southern half of the United States, these high temperatures won’t stop the first day of fall. With fall comes the changing of leaf colors, and deciduous trees will lose leaves. Why trees lose leaves is not a mystery. Managing trees in the winter has unique challenges, and you can read about some of the solutions in these three blogs:
- Why You Need to Water Trees in Winter
- Five Tips for Watering Trees in Turf
- Five Tips for Watering Trees During a Drought
Why Trees Lose Leaves
Deciduous trees lose their leaves in the late fall and early winter. It occurs at different times across the U.S., mainly due to weather. In Southern California it is not unusual for deciduous trees to still have leaves at Christmas. Cold temperatures in the winter can freeze the water in the soft vegetation in the leaves and stems. The damage could be so harsh it would kill the tree. The shedding of the leaves is a defense mechanism so the trees can survive even when winter temperatures are very low. This also helps the trees conserve water and stay alive until Spring.
Evergreen trees are different. They have leaves that are tightly rolled, resembling a needle. These needles are resistant to cold and stay moist and green during the winter. Many landscapes take advantage of a combination of deciduous trees and evergreen trees. The deciduous trees, with their broad leaves and changing colors, make a dramatic visual in landscapes. While the evergreen tree during winter provides a beautiful visual of a living tree giving hope for Spring and helping get us through winter. Interestingly the evergreen trees are also primarily dormant during the winter while looking the same as in summer.
Changing Leaf Colors
As daylight hours shorten in the fall and trees start slowing down for the winter they do not produce as much chlorophyll. Chlorophyll is the chemical in leaves that make them appear green. It also helps the tree turn sunlight into glucose, which trees use for food. As chlorophyll production slows down, the color of the leaves present themselves naturally, and we experience the beautiful fall colors. It seems lately these are best viewed with the addition of a pumpkin-spiced latte.
Trees are and will continue to be the most valuable assets in our landscapes. Fall can be one of the best times of year for understanding their value. However, year-round trees make a positive difference in landscapes, and learning how to best care for trees often makes the difference between a spectacular landscape and a mediocre one.