JoAnne Skelly
Suddenly, the deciduous trees and shrubs are turning color. It seems as if the date saying it’s fall resonated with the trees’ color clocks. One day the aspens high in the canyon to the west of us were green and the next day yellow hues became visible.
The day after that showed swathes of yellow. We drove up to the meadow at Mt. Rose today and many of the aspens have turned yellow, with some turning a glorious orange. The other mountain plants are putting on their autumn-colored clothes as well.
The Amur maples and ash trees in our yard are also changing their visual tones, more subtly than up on the mountains. The sumacs are showing colors from yellow to deep burgundy. I suspect they will be completely red soon.
The night temperatures have not been cold, and the days have been quite warm for this time of year, helping the colors develop. However, temperature is not the only factor that influences color changes.
Shorter days with less intense sunlight play a significant role. With less light, plants slow down the production of the leaf pigment chlorophyll that makes leaves appear green. When this slowdown occurs, the yellow, orange and brown pigments (carotenoids) and the red and purple pigments (anthocyanins) are revealed providing those luscious fall colors.
With the warm temperatures, there is a lot of sugar in leaves to encourage the red pigments. Adequate soil moisture also encourages stronger colors, and we just had a nice rain.
I hope you are thinking about planting trees, shrubs and perennials now, as well as bulbs, of course. The soil is the warmest of the entire year, yet the air temperatures are mild. This means that roots can establish easily.
Since the soil stays warm for quite a while, roots can actually grow for most of the winter. Fall planted trees usually put on two to three times the leaf growth in the spring as spring planted trees.
The mild temperatures now are gentle on the plants so there is little water stress. This really is the best time of year for planting. One reminder – if you do plant in the fall, remember to water the newbies regularly throughout the winter.
We rarely get enough precipitation, often enough, to keep young plants moderately moist. I received 30 daffodil bulbs for my birthday. Since my birthday is in August, my bulbs arrived yesterday. I will plant them in a couple of weeks for a burst of happy color in early spring. Color in leaves and flowers is one of nature's best gifts.
JoAnne Skelly is Associate Professor & Extension Educator Emerita at University of Nevada Cooperative Extension. Email skellyj@unr.edu