Originally posted 11/28/2013
The fall colors in North Texas not only appear to be more vibrant this year, but the timing of their autumn palette is perfect as it is Thanksgiving week, 2013. As I look out my 3rd story window at work, I see the greens, reds, russets, and yellows of live oaks, maples, red oaks, and elms, along with the gorgeous medleys of fall colors typically found on Bradford pears.
It can be puzzling that some fall seasons are more colorful than others. It can also be frustrating that one year your maple keeps its deep red leaves right up to winter and the next; it drops its leaves before there is time for its true colors to be shown.
While I must admit there aren’t many 100% absolutes in gardening, there are a couple of reasons our season is especially beautiful this year.
First of all, it is important to understand that it is the vital substance chlorophyll that gives plants their green pigment. I spoke of this in an earlier blog post regarding my albino sunflower seedling find and how I was disappointed to learn it wouldn’t survive long without chlorophyll. Along with being an essential element, the green color of chlorophyll dominates most other pigmented substances found in a plant. However, as sunlight lessens with the shorter days of fall, the production of chlorophyll gradually slows and allows the subdued carotenoids (yellow, orange and brown pigments), ever present but overshadowed by the green of chlorophyll, to burst through the leaves. And, again, while chlorophyll is indeed crucial to plants, our temperate trees and shrubs are programmed to prepare for its reduced production in the winter by storing up essential sugars throughout the warmer growing seasons. In fact, when sugar production is at its peak during the early fall, it is the excessive sugar found in the leaves of some trees that is responsible for the third type of pigment we see in the fall – anthocyanin, accountable for red and purple hues.
So what is it that has brought us in North Texas such beauty this year exactly at the right time? A perfect combination of temperature and moisture conditions:
According to the US Forest Service,
- a succession of warm, sunny days with cool (but not freezing) nights as fall approaches will bring out the best tree colors, and
- a severe summer drought will cause a delay in the timing of the turning of the leaves.
Of course, there are other temperature and rain combinations that will produce good results earlier in the season, and on the contrary a premature hard freeze can cause leaf drop and abort the process.
I conclude today’s post by giving thanks for our beautiful trees as they surround us with an array of autumn hues at optimal timing to enjoy during our holiday weekend. The summer drought and the recently warm, pollen-filled days have offered us a small blessing after all.
Until next time,