The Garden Life: Autumn weather creates colorful foliage

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Gardening enlivens the emotions and keeps our creative imaginations alive. Something about the change of seasons, especially the metamorphosis into autumn, illuminates these feelings for me. Distinctly cooler evenings and a veritable pinch of chill in the morning air brings me to the brink of inspiration. The end of the garden season is nigh but dreams of my future garden wait, just on the tip of my tongue.

When we think of the garden in November, most of us conjure up all the colors of fall. Even as the temperatures of the days change from cool to crisp to cold, it’s a medley of warm tones that hold sway in our thoughts. There is orange, of course, like that of pumpkins, “Ambercup” squash and Mexican sunflowers. The picture changes daily with a mix of complimentary color shades unique to the season. Russet, umber, amber and dun.

As a child, I thought that cold weather was the only reason that leaves changed colors. I was surprised to learn that the most important factor in the onset of fall color is the length of daylight. As the amount of light diminishes with each new day, the short, warm daytime hours and the chilly nights trigger a physical change in leaf color. In a good autumn, weather conditions cooperate to create a classic autumn palette.

The scientific interpretation of autumn color is told through the perspective of chemical reactions. As the amount of light diminishes with each day, plants slow down their production of chlorophyll, which is the green pigment in the leaves. Eventually, production comes to a complete stop. Carotenoids are the yellow and gold pigments within a plant’s leaves that begin to show through as the green fades.

During these autumn days, when the degree of sunlight and temperatures collaborate, sugars are produced in the leaves of trees, shrubs and many perennials and groundcovers. At the same time, the veins that run through the leaves are gradually constricted by crisp night air, which prevents the sugars from moving out of the leaves and into the tree. These conditions produce anthocyanin pigments, which give us the brilliant reds and purples.

Fall foliage reminds us that nature has a genius for design. Around the Thanksgiving holiday, the landscape gives us new ideas for table settings and flower arrangements. At least for November we shy away from pastels. The primary colors of summer are cut back as well. Instead, dried seed heads, fallen pinecones and the twisted brown branches of Harry Lauder’s Walking Stick (Corylus avellana “Contorta”) add texture to the outdoor garden and indoor decorations.

To the gardener, autumn is a visual reward for all of the thought put into the art and science of plant selection. Depending on the plants we have chosen, the show can be a blast of one intense monochromatic tone or a kaleidoscope of autumn hues. Each leaf on the red maple “October Glory” (Acer rubrum) turns from green to red in progressive stages, changing every day. Within a week, every leaf on the tree is a blaze of metallic scarlet.

Other trees and shrubs show their fall colors in a different manner. Each leaf changes colors at a different rate so one leaf is part green and part hot pink while the next is pink and gold or gold and russet red. The dogwoods, viburnums and spireas are fine examples of this mottled coloration. With an evergreen backdrop, these colors stand out like neon lighting.

Every year I am glad that I planted the garden for each of our four distinct seasons. If it were up to me, I would be out in it every day with that very thought in mind, continually planting for the season just around the corner. While I know I’ll spend many hours outside in the chilly late-fall and winter garden, the warm seasonal colors of holiday decorations entice me into the house to be with family, friends and a couple of red boy cats.

We can all agree that time seems to be racing by with each new day. Summer barbecues and cocktails on the patio already feel like distant memories as I throw on a long-sleeve sweater just to walk around the garden. Thanksgiving is just around the corner. It will most likely be an indoor gathering. I always hope that the day will be warm enough to leave the curtains wide open for a final look at the autumn garden. If it is cold that day, we may just light the fireplace to fill the house with warmth and all the fiery colors of the season.

Robb Rosser is a WSU-certified master gardener. Reach him at Write2Robb@aol.com.