Fall Means Frost & Colors
Fall is definitely in the air after this past week’s dreary and cool weather. Areas away from the lakefront woke up to frost this weekend.
From Green Bay to Madison and then just west of the lakefront, the average date of first frost is Oct. 4 to Oct. 10, while communities along the lakefront have their first frost between Oct. 11 and Oct. 24. This delay is due to the warmer lake water temperatures.
Leaves are changing quickly across the area and many believe that is due to the frost. It is just coincidence that the first frost is usually around the time of the color change. Color change is due to the lack of daylight that leaves need to create food, or chlorophyll. With less daylight, less chlorophyll is produced so leaves lose their green color. This past week was cloudy so colors have really popped out quickly.
When chlorophyll is no longer produced, the carotenoid which is always in the leaves, allows the yellows, oranges and browns to show. You get more red and purple leaves when you have a streak of sunny warm days and cool, but not freezing nights. The warm days create lots of sugar in the leaves and cool nights trap the nutrients in the leaves. Anthocyanins are produced to save the nutrients for the tree before leaf falls off and gives the leaf its red color.
This week will have warm and sunny days with cool nights, so look for a lot of red leaves in the next week or so.