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The Power Colors Of Autumn

A Personal Journal Entry For October

Stefan's Corner

Stefan Fediuk, Staff Writer

And so once again we've come to that time of year. It's autumn, and it's a good time for me to reflect on what's going on in my part of the Northscaping world and share some of it with you, wherever you may be.

Though the weather is turning quite cold in my home region here on the northern prairies with temperatures threatening to dip below the freezing mark, I can't help but look in awe at the breathtaking colors that this autumn has unveiled. Autumn is generally typified by a cast of yellow leaves in the lovely Pembina and Red River Valleys, as the dominant native tree species around here are bur oak, Manitoba maple (commonly known as boxelder elsewhere), green ash, basswood (American linden), American elm and quaking aspen. But this year something markedly different has occurred.

The aspens have a golden to orange hue this fall

It seems that the heavy rains that tormented us in the early part of the summer have had a wonderful and positive effect on the trees and have subsequently improved the fall colors. I have asked other colleagues if they have noticed anything different, and we all seem to feel that there is greater abundance of oranges and reds in the fall display this year. And this is not just where new plantings of trees and shrubs have been designed specifically to promote these colors; there is even a noticeable improvement in the color of older trees throughout the city.

Just yesterday I was visiting a friend's yard and noticed a considerable amount of orange highlighted in his green ash trees (Fraxinus pennsylvanica). What really caught my eye, though, was a silver maple (Acer saccharinum) that had a great deal of deep orange in the leaves. Now I know that there are some popular hybrids of silver maple which have been crossed with red maple (Acer rubrum), known as Freeman maples, to improve the fall color, but this tree had been there for years and had never shown anything more than maybe a pale butter yellow during the fall.

Colorful bur oaks in the neighborhood

Even the mighty bur oaks (Quercus macrocarpa), the stalwarts of our city, were displaying an early and pleasant display of orange in the leaves, where usually they turn a rustic brown. I figured there had to be something that triggered this increase in anthocyanins and carotene, which are the chemicals within plant leaves that are responsible for the red and orange colors respectively.

Another clue was that many, if not most of the Amur maples around town (Acer ginnala or A. tartarica var. ginnala, depending on your reference source) were sporting the most spectacular display of scarlets, reds, burgundies and maroons. Normally, our calcified clay soils cause these potential gems to be rather mute with yellowish orange or dull red fall color at best.

Then I recalled the process that is responsible for the leaf color change. Instead of an increase in anthocyanins and carotene as I had originally surmised, it dawned on me that there might rather have been a deficiency or dilution of chlorophyll, the chemical that produces the green in leaves. As I recalled the oak tree I had been examining, I remembered that the leaves were not as brown and leathery as they normally are. Instead, they had an soft, almost delicate appearance, somewhat uncharacteristic for an oak.

Again this lead me to believe that the excessive moisture of the early part of the season had affected the chemical composition of the leaves, making them more fluid. This resulted in the chlorophyll and tannins (chemicals responsible for the brown color) being diluted and breaking down faster, leaving in their wake the beautiful display of warm fall colors which we are experiencing in our yards and gardens this autumn around here.

Yes, this is what the Amur maples are looking like this fall!

Peak fall coloration also occurs when there is adequate moisture (i.e. neither too excessive nor too dry) in the soil and air. Also, daily temperature swings should range from a fairly warm day to a cool frosty night for optimal color. Furthermore, more sun during the autumn will help to increase the fall color display.

This isn't just restricted to the leaves of trees, but it also affects the color performance of countless fall blooming perennials and shrubs, like rudbeckia, chrysanthemums and most importantly hydrangeas. Just the other day, I came across a garden bed which I normally pass by every day of the year, only this time to stand and revel at the spectacle of the beautiful pink, red and maroon blooms of a mass planting of Pink Diamond hydrangeas (Hydrangea paniculata 'Pink Diamond'). I realized that I was not the only one, as many people who passed by were commenting on how beautiful the flowers were.

But alas, as I write this a cold weather system known as a "Colorado low" is moving north towards Manitoba, and this beautiful display will be short-lived for the Northscapers in its path. Luckily, in the warmer areas further to the south, my fellow Northscapers in Minnesota, Wisconsin and the Central Plain States, can expect their fantastic autumn display to continue for a time yet, so long as the weather cooperates. Maybe I'll make the trip down to see the red maples and sumacs in what I deem to be their most impressive outfit of any of the seasons.

So the next time any of us experience a summer where the endless rains seem to infer that the second global flood is at hand, let's remember that this adverse weather can have a positive effect on the plants when it comes to autumn splendor. But for now, I'll look out the window and watch as the premature snow starts to erode this joy of the harvest season, at least for my immediate world.

To my Canadian Northscapers, I wish you a Happy Thanksgiving Monday. And to my Northscaping friends in the United States of America, I wish you well this Columbus Day.

Happy raking, or shoveling, as the case may be!

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