When the summer air wraps around you like a heavy winter blanket, the very thought of a mountain forest’s cool shade can be absolutely thirst-quenching. Running streams, mossy banks and the forest’s many shades of green are all balms for the overheated mind, body and spirit.
For many people, August may be the month to hike new trails and paddle new rivers. But for gardeners, it’s a good time to explore the woods and learn lessons that can be applied to our own gardens and landscapes.
The first step toward enjoying a thriving garden is studying the site. So as you venture into the woods, take note of your surroundings. Are you on a slope, in a valley or ravine, or are you up on a ridge? Is it sunny or shady?
What’s the air like? Is it dry and warm or cool and moist? Use your nose and skin as observational tools. Does the air have a scent? Is it green and funky or brown and dusty? Bend down and dig into the soil with your hands. What does it smell, feel and look like? Is it dark, soft and crumbly or light, hard and stony? Notice the moisture levels of the soil and/or air. Is there any running or standing water nearby?
As you walk in the woods, you may notice how different types of plants and plant groupings change in response to site conditions. Typically, evergreen species such as spruce or fir, and moisture-loving Northern hardwood species such as yellow birch and mountain ash, will be more common at elevations above 4,000 feet, where it’s cooler and rainier. As you move lower down, drier ridges and peaks will tend to favor certain pines, oaks and members of the heath family: mountain laurel, blueberry and huckleberry. In contrast, the wetter slopes and ravines will host hemlock stands along with masses of rhododendron, dog hobble and mountain laurel.
Plant life in sheltered slopes and coves at lower elevations is rich and diverse, thanks to deep, rich soils and adequate moisture levels. This habitat may have you dropping to your knees in grateful prayer, but it’s also a reminder of the vital importance of matching plants with the right site.
As you continue on your walk, observe differences as you move from one habitat to another. Notice how quickly site conditions can change — and also how quickly the types and combinations of plants will shift in response to these changes. These transitional areas illustrate how well plants adapt to the many factors that affect them.
Be attentive to minor changes: Note how an otherwise-dry site can provide just enough moisture from a small, wet-weather spring or freshwater seep to sustain a beautiful patch of cinnamon fern. Don’t rush to judgment without further exploration!
During a walk in any of our local forests, you may come upon a spot that’s markedly different from what surrounds it. Look for a reclining tree trunk that tells the story of a high wind or lightning strike that caused it to fall, creating an opening that admits enough sunlight to allow more sun-loving plants to grow. At the forest’s edge, where it becomes meadow (or vice versa, depending on which way you’re traveling), there are even more visible changes. These warm, dry sites — which host grasses and colorful, sun-loving perennials and shrubs — may better reflect the growing conditions in your own landscape, as these human-made environments are more similar to the growth surrounding many home sites.
Before you leave the forest, be sure to note the different layers created by the various trees, shrubs and ground covers. Notice how big trees create the forest canopy — the uppermost layer of plants that often need more sun to grow and set seed. Smaller trees and shrubs form the subcanopy, or middle layer, which and can tolerate (and may even require) the shade created by the canopy trees. Beneath these are the smaller perennials and ground-covering plants, which typically need the shade provided by their taller neighbors.
Besides enabling you to learn from nature and develop a closer relationship to it, making these observations will help you better understand the various growing conditions present within a single site. Over time, you’ll begin to notice what’s thriving and what isn’t. Even if you don’t know its original habitat, the plant will tell you if the site is suitable. As you move plants around and bring in others, hopefully you’ll make decisions based more on the site’s soils, moisture and light levels rather than solely on the plant. You will come to know that sunny, dry and warm sites work better for oaks, pines, grasses, sun-loving perennials and shrubs such as coneflower, goldenrod, blazing star, yucca, sumac and sweet fern. Wetter, shadier sites with better soil will suit the growth of native azaleas and rhododendron, Christmas fern, black cohosh, cardinal flower, hydrangea, sweet shrub and silver bell.
Many plants, of course, can live in either type of site, given good watering till they’re established. While the list is long (if you include many of the versatile, introduced landscape plants) and some of these have already been mentioned, others to consider are river birch, maple, black gum, fringe tree and redbud.
Whether you’re looking to learn or simply want to get out on a hot, late-summer day to play or just sit and contemplate nothing, the forest is always a source of inspiration. Our time in the woods may be the most important time we ever spend — and the most important thing we ever do for our gardens, our children, their children and ourselves. And if we take what we learn from these forays and integrate it into our landscapes and gardens, a bit of that magic will follow us home.
[Allison Arnold is director of horticulture at The North Carolina Arboretum. She can be reached at 665-2492.]