Tag Archive | fall color

Plant Trees To Transform Your Landscape, Part 2

Sep23

 

 

Autumn Lake Tree Nature Leaf - pasja1000 / Pixabay

 

 

After reading Part 1 of “Plant Trees to Transform Your Landscape”, you’ve located the best spot where a tree will shade the house from brutal summer sun. Recommendations and practices presented here are based on climate and soil in the eastern part of the United States, where I live and garden, but the basic principles apply everywhere.

If your main objectives are shade, attracting wildlife, and less grass to mow, include masses of shrubs and perennials in the landscape plan as well. This article concentrates on planting trees, the dominant features in the landscape.

 

 

Native Plants vs. the Non-Natives

 

The choices offered in garden centers can be narrowed down to native species and non-native, or exotic, species. Within each of those groups are the original species and the cultivars (cultivated varieties). Developed by plant breeders, cultivars exhibit more ornamental or desirable—or just different—characteristics than the species.

Japanes maple Red Filigree Lace

‘Red Filigree Lace’, a delicate cultivar of Japanese maple.

Non-native plants originated in a different country or perhaps only a few hundred miles away. If the plant doesn’t occur naturally in your geographic region, it’s non-native, although some gardeners restrict use of the term to plants evolving in another country.

There are many beautiful plants, exotic to our shores, which we’ve enjoyed in our gardens. Japanese snowbell (Styrax japonica), Stewartia pseudocamellia, and the dizzying assortment of Japanese maples (Acer palmatum) are just too hard to pass up. You can compromise, if you wish, by including both natives and exotics.

To most garden center visitors, none of this matters. We buy plants that solve problems and look pretty in our yards. But, to explain the relevance of native species, I’d like to expand the subject.

 

The Benefits of Native Species

First, native plants require less pampering to get them established.

Species that evolved locally can tolerate fluctuations in weather patterns. Temperature extremes, rainfall, humidity, soil types, altitude, wind patterns, and local fauna shaped today’s ecosystems.

Second, gardeners concerned about local pollinators choose plants that foster bees, butterflies, and other animals that pollinate farm crops and wild vegetation.

Every third bite of food we consume is attributable to pollinators. But, you might make the case that since most crops are alien to this country, it shouldn’t matter whether we use native or non-native trees. But we need to consider what larval insects consume, and that’s foliage and other plant parts. Thousands of species—not just bees—pollinate our farms, orchards, fields, and forests.

Egg-laying female moths and butterflies, beetles, and other insects are very selective and seek the natives they evolved with to supply sustenance for the following generation.

Incidentally, honey bees are not native to this part of the world. They will, however, forage from plants grown here, many of which are related to the plants they evolved with.

Making a Case For Single Flowers

 

 

Flowers attract pollinators, which reap the harvest of nectar and pollen. But many double- and triple-petaled flowers have lost their nectaries, stigmas, and/or pollen-tipped stamens. Photos above clearly illustrate the loss of reproductive parts in a double amaryllis cultivar. If these hybridized doubles and triples have lost the ability to reproduce sexually, they can’t make seeds. They must instead be propagated asexually, or vegetatively, by cuttings, division, grafts, or tissue culture.

The anthers, supported by filaments, bear the pollen; the male portion of the flower, collectively, is called the stamen. Female parts comprise the stigma, supported by the style, and the ovary, with its ovules, deeper within the receptacle; the female portion is called the pistil.

Not all dense flower heads are pollinator wastelands, though. Species in the Asteraceae family, for example, have flowers that normally look full. This family includes all the composites, such as aster, coneflower, daisy, dandelion, rudbeckia, and sunflower. Their dense inflorescences are composed of small florets arranged in a head, called a capitulum. But the original species also have the necessary reproductive parts. The composites are one of the most successful groups of plants and are found on every continent except Antarctica.

At a local garden center last year, I watched bumble bees that were quick to land on thickly-petaled hybrid red coneflowers (Echinacea). They were equally hasty in their departure! The bees stayed on the red flowers for a fraction of a second, while they lingered on the less frilly flowers of other cultivars, mining several florets in each flower for their treasure.

Pollinators waste precious energy visiting barren double-flowered hybrids. True, not all doubles lack nectar and pollen. For the pollinators’ sake, though, select more species or varieties with simple flowers. Natural selection favors plants that set seed, of course, which is why most native plants have simpler flowers.

Photos below show examples of single-flowering cultivars. If you see a boss of stamens and pistils in the flowers, those plants can probably supply pollen and nectar to the pollinators. This is a fine point, granted, but one that is critically important to populations of pollinators, given the preponderance of double-flowering hybrids at garden centers.

 

 

Third, planting a multitude of native species helps secure the future of threatened or endangered insects and animals.

In many regions, songbird populations have declined by half due to human intervention. Some have disappeared entirely. Trees and shrubs that provide shelter, nesting sites, berries or seeds, and which host insects, can help bring back the birds. Abundant biodiversity is a valid protection against the domino collapse of interdependent species.

Civilization has claimed much of the insects’ natural environments, so each of us can play a small part in rebuilding habitats. Annual butterfly counts show drastic declines. Monarch butterflies, in particular, now have less territory available in Mexico, a major overwintering site, than in the past, when they migrated by the millions.

Maintaining brush piles for overwintering insects and animals will help repopulate your landscape early in the season. Hauling those materials off to the recycling center, however, is sure death for the insects tucked inside. Fewer insects = fewer birds and other animals.

Fourth, incorporating native plants into the landscape helps keep the entire food chain intact.

anole lizard

A green anole basking in morning sun.

Insects feeding on plants become food for frogs, lizards, birds, and mammals. They, in turn, become food for snakes, hawks, foxes, and other predators. In many ecosystems, insects native to the region are the foundation on which the entire food chain is based.

A rich diversity of plant material supports an enormous number of insect and animal species. Left undisturbed, populations find a balance among themselves. On the other hand, life in monoculture, such as a lawn, is sparse. Unfortunately, countless urban and suburban neighborhoods have become dead zones with all their natural vegetation bulldozed to the ground.

As we spray, mow, burn, or build in natural environments, species will continue their rapid decline. Certainly, we need places to live and work, but we can also “give back” by planting for wildlife instead of continually killing it off.

Check with your state’s native plant society, native plant finders, BeeCity USA, and the local agricultural extension service for information. In addition to these sources, find a knowledgeable salesperson at the garden center for practical advice and sources of plant material. Garden shows might feature vendors specializing in native plants as this branch of horticulture grows.

 

Native Species and Nativars

 

trees, red leaves in fall, native white oak

Red fall color in a native white oak tree.

 

Plant breeders have brought to the marketplace many cultivars of our native species. These nativars might have purple or red foliage instead of green, or double flowers instead of single. Perhaps they mature at a shorter height than the original species, making them a better fit for small properties.

Garden centers often stock varieties of native species, although those selling native plants might also stock the original species. By a comfortable margin, though, most of the trees and shrubs in U.S. garden centers are cultivars of non-native species. Many originated in Asia, a treasure trove of tempting horticultural novelties.

Red Leaves and Wildlife

 

native trees, dogwood, red leaves, flower buds

Red fall color and flower buds on native flowering dogwood.

 

Many trees develop red or burgundy fall foliage. Species native to the eastern U.S. with red fall foliage include sourwood (Oxydendrum arboreum), flowering dogwood (Cornus florida), black gum (Nyssa sylvatica), red maple (Acer rubrum), sugar maple (Acer saccharum), red oaks (Quercus rubra, Q. coccinea), and white oak (Quercus alba).

Beautiful fall color lures camera-toting visitors each year to the mountains, to New England, and to the Blue Ridge Parkway. The U.S. National Park Service provides an interactive map which tracks the progression of fall color.

Red- or purple-leaved cultivars sporting this color all summer are in high demand at garden centers. But if the point of planting trees and shrubs is for wildlife, we want to be sure the plants we choose will attract them. Each plant species has a particular menu of chemical compounds in their tissues that either attract or repel insects and animals. Organisms evolved a tolerance for these compounds…or they didn’t!

Purple and red leaves often repel insects due to their high levels of anthocyanins, the red pigments in the foliage. So, that defeats the purpose, doesn’t it? Not necessarily; these trees might have had green leaves that hosted insects before leaves turned red. Or insects simply tolerate the red pigments.

Oak trees support huge numbers of insects, birds, and mammals at various times during the year. This one genus, Quercus, hosts hundreds of species of moths and butterflies, although they often turn red in the fall.

Before planting a cultivar that stays red all season, though, find out if insects, such as mature caterpillars, will eat the leaves. This indicates that it could host insects for their entire life cycle. If all the larvae are tiny, however, when some larger individuals are expected, most might have crawled off to greener pastures.

If bees spend time working a flower and don’t fly off immediately after landing, that plant could be a good choice. Similarly, holes in the leaves indicate that the plant can host insects. Resources at the local university’s entomology department or botanical garden might have information that could help you choose plants that support wildlife.

The Untold Story

I’ve been packing the past couple of weeks, preparing to move to a rural location in northern North Carolina. I took a break from the work and sat on the deck, listening to the birds and insects.

One of those sounds was the hum of an approaching ruby-throated hummingbird, the only species summering in this area. Four feet away, and less than 4″ long, this tiny bird landed on a twig of the potted native dogwood tree, sitting right next to me. He then hovered near the flower buds (photo, above, with last year’s fall color), and I could see his tongue working the buds, one after another. These buds are tightly closed, yet he found something worth gathering, despite the presence of other flowers nearby.

Within a minute, another hummingbird arrived for the same reason, apparently. The two tiny birds fought for feeding rights, and the second one flew away after some impressive aerial maneuvering among the twigs. The first hummingbird continued searching for hidden sustenance held inside those buds. I’ve never seen this behavior.

My point is this: there’s much about the natural world that remains unobserved—a mystery to us—perhaps lending more credibility to the importance of using native plants in our gardens. (This section added 10/6/21.)

 

Deciduous Trees For the Eastern U.S.

 

Here’s a partial list of native and non-native trees that support wildlife. Large deciduous shrubs can substitute for trees in smaller spaces. Many other species might suit your purpose, so visit a few nurseries to see what’s available.

Most trees are sold in large plastic nursery pots, although you might also see freshly dug trees with their roots wrapped in burlap (“b&b”, or balled and burlapped).

  • American hop hornbeam (Ostrya)
  • basswood (Tilia)
  • birch (Betula)
  • black gum (Nyssa)
  • Carolina silverbell (Halesia)
  • chaste tree (Vitex)
  • cherry and plum (Prunus)
  • crabapple (Malus)
  • crape myrtle (Lagerstroemia)
  • dogwood (Cornus)
  • franklin tree (Franklinia)
  • fringe tree (Chionanthus)
  • hornbeam (Carpinus)
  • magnolia (Magnolia)
  • maple (Acer)
  • oak (Quercus)
  • poplar, cottonwood (Populus)
  • redbud (Cercis)
  • serviceberry (Amelanchier)
  • sourwood (Oxydendrum)
  • willow (Salix)
  • winterberry (Ilex verticillata)
  • witch hazel (Hamamelis)

 

maple trees fall color

Native red maple can have yellow, orange, or red fall color.

 

Most of the trees listed above have small- or medium-sized species or varieties. Compare suitability of native and non-native species within the genus. The familiar weeping willow, for example, is non-native and quite messy in the landscape. But smaller native willows behave better and host a large number of moths and butterflies.

Research disease resistance, flowers for pollinators, fruits for animals, sun or shade preferences, and soil types. Consider planting species that drop excessive amounts of fruit, acorns, or seedpods farther from the house and paved surfaces.

Also look into the tree’s habit of growth. A specimen with horizontal branches softens the strong vertical lines of a house. Pay close attention to utility poles and wires. Don’t plant trees near them that the utility company will butcher in future years.

Trees with invasive surface roots should be reserved for areas far from structures, pipes, and vegetable gardens. Find out from your town how close to the street or the property line you’re permitted to plant trees. Don’t forget to call 8-1-1 to locate underground utilities before digging.

Chionanthus, the fringe tree (photo, below), is a beautiful bloomer for gardens. This multi-stem plant has 2 species commonly available (C. virginicus, C. retusus), one native and the other from Asia. Male plants have larger flowers, but females set deep blue fruits for birds. The plants, however, are rarely sexed at the nursery.

 

fringe tree with white flowers

Fringe tree.

 

The Hollies

Gardeners have used hollies in gardens for centuries. We can choose among deciduous and evergreen species.

Holly Red Christmas Winter Berry - 165106 / PixabayThe hollies (Ilex spp.) are another genus of primarily dioecious (Latin for “two houses”) plants that fruit on female plants. They ordinarily require a male plant, or pollenizer, to set fruit, although holly pollenizers (the males) themselves do not set fruit. Modern breeding techniques have yielded several cultivars that can make berries without pollination.

Ask your nursery salesperson for specifics regarding the need for pollenizers and how close they should be planted to female hollies. Choose the male hollies carefully; they must be closely related to the female holly and bloom at the same time. Incidentally, holly flowers are often nicely fragrant, and the bees love them! Just don’t shear them off after the buds have formed. Pruning should be minimal if you want flowers and fruits. And bees.

 

The Curious Case of Crape Myrtle

imperial moth

The Imperial moth.

Lagerstroemia indica is an extremely popular landscape tree or shrub in USDA zones 7-9. Crape myrtle, from China and Korea, was first introduced to the southeastern U.S. over 200 years ago. Adapting readily to our hot, humid summers and sometimes drought, it blooms for months despite the adversity.

What makes this non-native plant peculiar is a native moth’s preference for its leaves even when offered a multitude of its local favorites. Last year, I raised caterpillars of the huge Imperial moth. They went for the crape myrtle every time, ignoring all the others. Unless female moths instinctively target this species to host their young, the caterpillars will not likely eat these trees to the bone any time soon.

Several songbirds, including American goldfinches and juncos, feed on the seedpods.

 

Evergreens

You might prefer an evergreen specimen instead of a tree that drops its leaves in autumn. Look into arborvitae, chamaecyparis, hemlock, certain holly species, juniper, pine, rhododendron, spruce, and yew. Consider the shade evergreens will cast in winter, and whether sunlight might be blocked from entering windows or melting ice on the driveway.

Although not all evergreens are native to this part of the country, they make suitable nesting places and provide shelter in inclement weather. A dense border of evergreens can block fierce winter wind for a considerable distance downwind.

Soon after moving into the Maryland house in the 1980’s, I planted a chamaecyparis with deep green whorled foliage. Although it was supposed to get only 6′ tall according to the nursery, it grew to about 20′, when it was cut down by the people who bought the house from me. I left it in the front yard because birds raised a few families among its evergreen branches every year. And it looked gorgeous in the snow.

 

trees in the snow, my house in Maryland

Chamaecyparis on the right, after 2010 blizzard. Sourwood on the left.

 

 

Good Looks

 

If you’re landscaping purely for aesthetics, plant a tree with characteristics that appeal to you. It’s your property, after all. Besides, all trees provide cover and nesting opportunities, even if they’re passed up by caterpillars.

Perhaps elsewhere you could grow perennials that offer food to wildlife. Planting a bed of milkweeds among the shrubs, for example, will help the monarch butterflies (photo, below).

While you might not consider insects important in your landscape, and, in fact, have invested considerable time and expense eradicating them, they are primary links in the food chain. A healthy landscape hosts a complex assortment of insects and animals. And with the rate at which natural habitats are losing out to development, it’s no wonder we see fewer ladybugs, butterflies, and songbirds in our neighborhoods.

Creating welcoming landscapes provides resting places for migrating birds. But they need natural corridors all along their path in order to find food and perching opportunities. We can help by planting at least part of our property with them in mind—every one of us! Provide food, water, and trees to rest in, and you might catch a glimpse of a bird you’ve never seen before.

I urge you to adopt a new attitude toward welcoming wildlife. You don’t need 10 acres to make a difference. A well-planted fraction of an acre will encourage many kinds of insects and animals to reside there. If you let them eat your plants and the sprayer hasn’t been used once this year, well done!

 

Monarch Butterfly Laying An Egg - Chesna / Pixabay

Monarch butterfly on milkweed.

 

 

Before Planting Trees

 

Let’s imagine a 2-story house and an appropriately proportional medium-sized tree. Your landscape plan calls for locating this tree off the southwest corner in the front of the house.

To prevent branches from rubbing against the siding in the future, you’ll want to plant the tree far enough from the house. Divide the mature spread of the tree by 2. Because plants tend to grow larger than the dimensions printed on the label, add a few feet to the measurement. So, a tree with a mature spread of 25-30′ should be planted 15′ or more from the corner.

While that little tree might look lonely out there, it will grow. Maybe that’s the extent of your garden project this fall. Or perhaps you’d like to develop a full garden on that side of the house with an underplanting of shrubs, perennials, and ground covers.

Walking a pathway through the garden to the side yard will feel like a walk through a park. This is a good solution where space is limited between your house and the neighbor’s. Consider your neighbor, though, and don’t plant too close to the property line. Perhaps the two of you could create an appealing garden that fills the space between both houses.

 

But first, it’s soil prep…please turn to page 2…

 

Headings:

Page 1: Are You Ready To Plant Trees?, Native Plants vs. the Non-Natives (The Benefits of Native Species, Native Species and Nativars, Red Leaves and Wildlife, The Untold Story), Deciduous Trees For the Eastern U.S. (The Hollies, The Curious Case of Crape Myrtle, Evergreens), Good Looks, and Before Planting Trees

Page 2: Soil Preparation For Trees (Slope, Outline the Bed, Heavy Clay, “How Deep?”, Adding Amendments, Organic Matter, and Time To Plant Trees (Trees In Pots, B&B Trees, Backfill, Edge, Mulch, And Water)

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Plant Trees To Transform Your Landscape, Part 1

Aug7


2021

 

It’s Time To Plant Trees!

 

 

 

 

As summer’s sizzling temperatures begin to cool off, our thoughts turn to new gardening projects. Fall is a great time to plant trees and shrubs. At that time, garden centers bring in fresh plant material, so you’ll have a wide variety to choose from.

After leaves drop from deciduous plants, roots no longer need to provide water to foliage, making fall the perfect time for landscaping. New roots, though, continue to grow well into autumn, while soil temperature remains above 40°F. By springtime, new leaves will draw water from a more extensive root system, so you won’t have to water as often as you would when planting trees in leaf.

Although you can plant trees and shrubs in full foliage, they will need frequent irrigation to get them established. The warmer the temperature, the more water the plant will require. Summer sun bearing down a dark nursery pot stresses the root system and can prevent root growth on the hottest side of the pot. It follows that during the summer months, roots would rather be in the cool earth than exposed to hot sun. Planting leafy trees just requires more attention from the gardener.

Most evergreens also can be planted in autumn. Their foliage at that time transpires less water to the atmosphere as temperatures cool down and day length shortens.

 

 

trees and sky

 

 

Room For Improvement

 

During my search for a new home, what always attracts my attention first is the presence of mature trees. The absence of trees means more grass to mow, for a while, anyway. Not my cup of tea.

Because the Covid-19 pandemic has kept us closer to home, we can’t help but notice areas that could use improvement. Is the sunroom or the shed a bit too toasty in the afternoon? Gazing at the computer screen hour after hour? Now that you’re working from home, looking upon a pretty garden outside the office or pulling a few weeds would provide a needed break. Perhaps you’ve discovered that connecting with nature relieves stress and gives you a feeling of calm and comfort.

Those are just a few reasons to plant trees and spruce up our gardens. Converting high maintenance lawns into gardens with colorful trees, shrubs, and flowers not only enhances aesthetics, but also increases the value of our homes. And with all this talk of carbon footprints and deforestation, perhaps you’re eager to participate in the solution.

 

 

Plant Trees To Transform Your Landscape, In Two Parts

 

Part 1 of “Plant Trees To Transform Your Landscape” addresses seasonal changes, drawing a landscape plan, reasons for planting trees and shrubs, slope, and practical considerations.

Part 2 of “Plant Trees To Transform Your Landscape” details soil preparation and the process of planting trees in the landscape. I also write about native plants vs. the non-natives, and how they affect populations of insects and animals.

 

 

The Sun’s Path

 

sun's path

The sun’s path across the sky in North Carolina, summer and winter.

 

Start thinking about your landscape now, before summer’s discomfort fades from memory. Notice how the sun’s arc changes from month to month, and how, by mid- to late summer, it’s already lower in the sky. My little succulents lining the south-facing bay windows get more direct sunlight now than they did a month ago, when the sun was directly overhead.

You can block much of the heat and sunlight falling on the south (northern hemisphere) or west side of the house with a deciduous tree or a group of trees. If you want maximum sunlight coming indoors during the winter, however, avoid planting trees right outside south-facing windows. Instead, shift the trees toward the southwest or the west, which will give you more sun in winter and shade on a hot summer afternoon.

Although deciduous trees drop leaves in autumn, bare branches and twigs will cast some shade. But with carefully placed trees—not directly south—shade will come from smaller twigs on the canopy’s periphery rather than from stout trunks and limbs.

Large evergreens block winter sun at a time when it is most welcome if they’re planted near south-, southeast-, or southwest-facing windows. Consider planting them farther out into the landscape and where they can reduce winter wind from the north or the west. Or use shorter evergreens that mature below windowsill height. Thick borders of twiggy deciduous plant material can decrease wind speed, but not as effectively as evergreens.

 

For the Record

It helps to keep a record of these seasonal changes. Visualize how tree placement will affect sunlight falling on your house or coming through the windows. Knowing a tree’s mature height and spread will help determine where to place it for maximum solar gain in winter and shade in summer.

Avoid planting trees too close to the house, where leaves, flowers, and fruits will litter the sidewalk and clog the gutters…not just in year 1, but also in year 31. Realistically, though, debris will get into uncovered gutters and leaves will swirl around paved areas, but planting trees far enough from the house will obviate the need for annoyingly frequent maintenance. In addition, limbs growing toward the house will require trimming, and the result often falls short of appealing.

These are merely guidelines that I’m suggesting, but, ultimately, it’s your property and your choice.

Let’s not forget the advantages of planting evergreens for winter protection. A dense planting of evergreen trees and shrubs can mitigate the brutal impact of winter’s fury. That can make living in and working around your home more comfortable, while lowering energy bills at the same time. Remember that winter shade on an icy driveway will delay rapid melting.

Try to recall the direction of prevailing winter winds, which usually varies from the direction of summer breezes. You can research local data from the National Weather Service.

 

 

Drawing Up the Plans

 

sketch to scale when planting trees

 

 

Tools Of the Trade

For accurate and detailed drawings, use an architect’s scale, a triangle (for straight edges and right angles), graph paper (for the base plan), tracing paper, a mechanical pencil, and an eraser. A plastic template with round holes of varying widths can be useful for extensive landscape projects.

The final design can be drawn on the more substantial vellum, if you wish, using colored pencils and markers. But, for those homeowners intent on planting a few trees and extending a garden, paper and pencil might more than suffice.

Community colleges and, sometimes, botanical gardens offer classes in landscape design. They might have sources for these tools, or you can find them at art supply companies.

 

Start the Sketch

Draw a sketch of your home’s footprint and property lines on graph paper. Use dimensions from a copy of the plat plan, if you received one when you bought the house. Pencil in existing vegetation, hardscape (structures and solid surfaces), prevailing wind directions, drainage patterns, slope, and a north arrow.

The 1/4″ scale, where 1/4″ on paper equals 1′ in the landscape, was satisfactory for almost all residential designs. For the largest projects, though, I used the 1/8″ scale. I measured the property, copied the plat plan, and drew, to scale and in permanent ink, all features that were to remain. This base plan depicted an aerial view of the property’s features, including locations of doors and windows in the home’s outline.

Then I drew preliminary plans, in pencil, on tracing paper taped (with removable drafting tape) to the base plan. You might go through several sheets of paper as different ideas take hold. That’s why it’s available in rolls!

Sketch ideas for how your family will use the property. You might include spaces for a sunny vegetable garden, shrubs and trees for butterflies and nesting birds, or a pond. In that case, pencil in the tallest plants either far from those areas or to the north, where they won’t cast shade for many years. Trees that grow less than 15′ or 25′ tall at maturity fit more comfortably in tightly clustered neighborhoods. Consider your neighbors, too, when including trees in the plan.

Now, of course, many landscape designers use software programs that cut short the labor involved in drawing plans by hand.

Also, keep in mind that the actual layout of the plants might necessitate shifting them somewhat from the locations drawn on paper. Before planting, place the potted trees and shrubs in their intended locations, and double-check the placement from all angles.

 

Elevating Your Skills

Drawing elevations, or vertical perspectives of the house as it sits in the landscape, supplies a more complete picture of your property. We plant trees, shrubs, and other plants around the house to anchor the structure to the land. Keep in mind that 10′ indoors looks much smaller outdoors, so expanding the beds will impart more appropriately scaled proportions.

An elevation of the front of the house will help you envision how the plantings will look from the street. Likewise, views from the back windows could be improved by adding a tree, or 3 trees, and masses of colorful shrubs and perennials near the fence. Remember to include hardscape and windows, doors, and the roof in your sketches. Then pencil in the existing plants from near to far, to scale, and see how they layer against each other. Additional drawings might depict tentative designs starting with no plants or having the biggest offenders removed.

This extra step could illustrate the need for some relief from all the short plants on one side of the property, or how the other side is too heavy with evergreens. If you add color to the elevation, you’ll see where you could repeat a cluster of flowering plants or where there’s too much yellow.

Maybe there are too many mounded forms, and the composition could benefit from a bold upright specimen or a fine texture, such as ornamental grass. Details in the elevation drawings help illustrate where contrast, color, height, repetition, or depth might be missing. Be sure to consider the color of the house and the trim when designing your landscape.

Simple Might Work Better

Perhaps the elevations reveal how busy or spotty the landscape appears, and how it could benefit from a simpler menu with fewer types of plants. The elements in the home’s landscape, when viewed from the street or from a distance, look more harmonious when the garden has only a few specimen varieties and masses of supporting plants.

This doesn’t rule out all those fascinating little plants tucked in here and there. But use those smaller plants along a path or by the patio to appreciate up close.

Symmetry vs. Balance

Planting symmetrical gardens on both sides of the front door might be your go-to style. Sure—that’s easy! But to give your landscape that something extra, try to achieve balance without symmetry. Balance requires using some of the same or similar plants on both sides, but not necessarily in the same quantities.

Symmetry is more difficult to maintain when one arborvitae grows faster than the other due to differences in sun exposure. Or one bed of reblooming daylilies grows better than the one that’s closer to the neighbor’s Norway maple. And most homes simply aren’t symmetrical.

Depth Perception

Imagine your front yard with taller plant material in a raised bed near a streetside corner. Maybe a spacious area could use a few large beds, which remove even more of the lawn. Dimensions of the property and existing features will determine the most appropriate placement of these islands. The plans I drew incorporated irregularly shaped beds, with broad, naturally curved edges instead of straight lines.

Adding a small tree or an uneven number of shrubs with drifts of perennials and ground covers introduces the concept of depth, partially hiding the front of the house from full view. Some open space—a void—near the center, showing the front entrance, creates a contrast. This sense of mystery—where not everything is revealed in one glimpse—adds a dimension that’s hard to describe. But you’ll know it when you see it…or don’t see it.

One tip about planting a tree: don’t plant it dead center in the yard or in a bed! Use the “Rule of Thirds” when locating the tree. Place it closer to the edge of the property, framing the view, or about one-third of the distance from the far end of a bed. A tree in the center abruptly bisects a view, which is uneasy on the eyes. Similarly, I prefer not to plant an upright evergreen between 2 windows.

If space is limited between your house and the neighbor’s, consider planting a generous bed—the full width—on your property. Then add a mulch, brick, or flagstone path from the front yard to the side yard, and plantings on both sides. Given ample room, place the tree on the outside of the path. This gives you that nice feeling of walking through a park.

Perhaps you and the neighbor can develop a landscape together for a more harmonious setting. When I lived in Maryland, a neighbor and I planted the entire area between our driveways, but the man who bought my neighbor’s house replaced all the plants on his side with sod. “Just in case”, I had planted a monarch birch on my side of the property line before he tore out blooming shrubs and perennials. Nevertheless, the see-through character of the finely-twigged birch tree lent that feeling of depth to our front yards.

 

House Wood Family Driveway - paulbr75 / Pixabay

 

Take This Photo, For Example

Taking advantage of the depth of the front yard gives opportunities for repeating plant material without having to rely on symmetry. Research shows that people attach greater value to properties with attractively orchestrated plantings comprising wider beds and curved edges.

Enlarging the foundation plantings by bringing in a specimen and groups of plant material is usually more appealing. Try adding large curved beds in your drawings rather than narrow beds lined up against the wall. Curves soften rigid straight edges.

In the photograph, above, this landscape would gain depth by adding a new curved bed in the corner between the near side of the sidewalk and the driveway. I’d plant a small tree, several small flowering shrubs or evergreens, and flowers in this bed. Lastly, repetition, using the same ground cover on both sides of the sidewalk, not necessarily lined up, completes the picture. (Well, I might rethink those ornamental grasses…and…)

When installing a new sidewalk near the house, place it farther from the house, if possible, to accommodate more creative plantings.

 

 

Options For Cooling

 

Diagonally off the northeast corner of my last house in Rockville, Maryland, I planted a sourwood tree (Oxydendrum arboreum). This deciduous tree has spectacular red fall color. Although the tree is a slow grower, I selected it for its ornamental features: multi-stem trunk (usually sold with a single trunk), fine twigs, flowers after the peak spring season, pest-free foliage, and long-lasting fall color. With all those desirable features, I forgave its persistent seedpods.

During the growing season, the sourwood blocked morning sun, from the east-northeast, and helped cool the living room and the master bedroom upstairs. But, with winter’s sun rising in the east-southeast, the leafless tree did not affect light entering those rooms. In regions where the temperature climbs quickly early in the day, consider planting a tree to shade the morning sun.

styrax snow charm

Japanese snowbell.

On the west side of the property, monarch birches (Betula maximowicziana) provided afternoon shade. The fine texture of their leaves and branches cast a delicate shade, and those beautiful chalky white trunks contributed year-round interest. This species can be quite variable in trunk color, from white to gray to brown. I also planted the species Japanese snowbell (Styrax japonica), a small umbrella-shaped tree, off the west side of the brick patio.

When we first moved into the house, there was no relief from intense summer sun. Planting trees made good sense for this house with little insulation, original single-pane windows, and an inefficient HVAC system.

Over the next three decades, I renovated the entire house, insulated the attic and under new siding, planted a woodland, and greatly reduced our energy bills. Replacement double-pane windows, with that heat-reflective coating, were expensive, but worth it.

 

Headings:

Page 1: It’s Time To Plant Trees! (Room For Improvement), The Sun’s Path (For the Record), Drawing Up the Plans (Tools Of the Trade, Start the Sketch, Elevating Your Skills, Simple Might Work Better, Symmetry vs. Balance, Depth Perception, Take This Photo, For Example), and Options For Cooling

Page 2: Beautiful Trees In the Garden (Lessons From Well-Designed Gardens), First, Call 8-1-1, Establish the Hardscape, Dealing With Slope, Why Should We Plant Trees and Shrubs? (Planting Trees and Shrubs Can:, Finding Help), Choosing Plant Material, and Next: Part 2

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Pages: 1 2

Mabry Mill On The Blue Ridge Parkway

Nov21

 

Mabry Mill

 

 

Mabry Mill

Mabry Mill is among the most photogenic stops on the Blue Ridge Parkway.

 

 

Last month, a leisurely drive took me to Mabry Mill in Meadows of Dan, Virginia. It was an easy detour from a few of those towns in northern North Carolina I had been exploring. During this pandemic, with social distancing in mind, day trips are pleasant diversions. My mother and I called them “mental health drives”.

I’ve spent the past few months looking for property with more sun, more space, and no homeowners’ association. The goal: large gardens for pollinators, butterflies, and birds. Raise greens and vegetables, and maybe a dog. Fix it up while working part-time? Open a little plant shop? The possibilities are exciting! With the vaccine apparently a likelihood, maybe more properties will soon come to the market.

For years, the western part of North Carolina was the location of choice. But, for the past month or so, I’ve widened the search to include counties in the northern part of the state. Lovely area, beautiful terrain, home to several vineyards. This is where people waved from their riding mowers as I drove by.

 

 

Getting to Mabry Mill

 

driving the Blue Ridge Parkway

Driving along the Blue Ridge Parkway.

 

The mill is located at milepost 176.1 (watch for signs) on the Blue Ridge Parkway and is administered by the National Park Service. This is a truly memorable drive and part of the National Scenic Byways system. The Blue Ridge Parkway winds 469 miles through the southern Appalachian Mountains. Elevations range from 649′ near the James River, Virginia, up to 6053′ on the slope of Richland Balsam Mountain (milepost 431) in North Carolina.

The Parkway connects the eastern side of Great Smoky Mountains National Park, which straddles the border between Tennessee and North Carolina, and Shenandoah National Park in Virginia. It continues northward as Skyline Drive, from where it intersects with U.S. Interstate 64 near Afton VA, to Front Royal VA. The Blue Ridge Mountains are part of the larger Appalachian Mountain chain.

But don’t expect to whiz by at interstate speeds; this is a slower road, with over 380 stopping points. There are many intersections along the faster U.S. or state highways where you can pick up a local stretch of the Blue Ridge Parkway. And gas up the car before reaching the Parkway because there are no filling stations on this road.

 

Caution

Keep in mind that people live and work here, so there might be farm vehicles on or crossing the Parkway. And check with the National Park Service to see if hazardous conditions or inclement weather might have closed parts of the Parkway.

 

Camera’s Ready

 

Trails cabin

Trail’s cabin.

 

Very picturesque. The entire area presents scenes of astonishing beauty, with views of pastoral landscapes, deep valleys, and mountain vistas. If you need to get away from it all, come to the Blue Ridge Parkway.

The “blue” in Blue Ridge derives from the Cherokee Indian description for the mountains, an area they and their ancestors have inhabited for over 10,000 years. Their term translates to “land of blue mist”. Isoprene compounds (hydrocarbons) are released from and protect the trees in hot sun, cloaking the distant hills in a bluish haze. The Mohawk, Iroquois, and Shawnee also inhabited this mountain chain, with the Cherokee centered around the Great Smoky Mountains at the southern terminus of the Blue Ridge Parkway.

This was my second visit to Mabry Mill, and I had a particular goal in mind: pictures of fall foliage! Although there was some color in the trees and shrubs, the bright reds and oranges of sourwood and maple, and the glowing gold of hickory, had already passed. A gentleman in the restaurant informed me that, just a few days prior to my visit, a wicked wind had stripped much of the fall color from the trees.

Photographers after the perfect shot of the mill and its reflection waited for the pond water to stop rippling after a young boy had stirred it up. But no one complained. He was having a great time! A few of us exchanged “Oh well” glances, and made sure we were positioned to capture the moment.

 

Mabry Mill grounds

Entering the grounds of Mabry Mill.

 

 

Building Mabry Mill

 

Edwin B. Mabry and his wife, Mintoria Elizabeth (“Lizzie”), had acquired the property and water rights around 1905, and finished construction of the gristmill three years later. By 1914, the gristmill, the sawmill, and blacksmith and woodworking shops were providing services for residents living in the area. A sorghum evaporator and the remains of the whiskey still also can be seen.

Mabry Mill flume

A flume channeling water toward the mill.

Mabry built a system of concrete tributaries, which collected water from streams above the mill, and directed it toward the wooden flumes (photo, right). Those flumes, in turn, channeled water toward the race, which fed water to the overshot waterwheel.

Because the water flowed slowly, the gristmill (called a “slow grinder”) ground corn with less friction, preventing the grain from overheating and burning. This earned the Mabrys a reputation in the region for producing products of excellent quality.

A few years after the mill and the shops were operating, around 1918, the Mabrys built their new home. It has since been replaced with a wooden structure once owned by the Marshall family (photo, below). The house on the site was built in 1869 near Galax, and donated to the National Park Service in 1956.

 

appalachian house

The old Marshall house.

 

The National Park Service

The Parkway’s construction began in 1935 at Cumberland Knob, milepost 218, just south of the border between North Carolina and Virginia. In 1938, two years after Ed Mabry died, the National Park Service purchased Mabry Mill.

Restoration of the historically significant mill and other buildings was completed in 1942. By then, gristmills had been rendered obsolete by more efficient large-scale milling operations and transportation networks that shipped products throughout the country.

The site is home to the restored mill, the wooden residence, and the workshops. This property includes short walking trails, a restaurant, and a gift shop, where you can pick up publications and maps. The restaurant closes for the season in early November, so check first if you’re hungering for their famous pancakes.

On certain days through the year, the National Park Service conducts craft demonstrations recounting ways of the past. They also bring in live musical performances to entertain visitors. The day I was there, Park Rangers Chris and Tabitha welcomed questions and shared information about how residents met the many challenges presented to them at that time. Each year, hundreds of thousands of travelers from around the world stop at the mill.

 

 

Seeing how others lived just 100 years ago gives me renewed appreciation for our more modern conveniences. Now that my mother has passed, I enthusiastically look forward to life in a more rural location…one with those modern conveniences.

 

 

Farther Up the Road

 

yellow flowers of witch hazel at Mabry Mill

Native witch hazel, Hamamelis virginiana, in bloom at the mill.

In no rush to get home, I drove for another two hours or so, northward on the Blue Ridge Parkway. There was so much to see; each stop had its own unique view or plant life or structure to learn about. Trail’s Cabin, Shortt’s Knob Overlook, Rocky Knob, Rakes’ Mill Pond…and that’s only one small segment. Informative signs provide more details at the various sites.

“There’s something for everyone” along the Blue Ridge Parkway. If you’re curious about the history of a region or its natural wonders, if you enjoy photography or painting, bicycling or walking the trails, it’s all here. Check before you go to see when campgrounds, visitor centers, and picnic locations will be open.

Within a few miles of the Parkway are hundreds of attractions, including museums, folk art centers, performance theaters, lodging, restaurants, water sports, caverns, and fishing opportunities. Enjoy the friendly vibe or the local craftwork in any of the quaint shopping districts not far from the Parkway.

 

 

Biodiversity

 

pink thistle flowerThe Parkway accommodates tremendous biodiversity. According to one pamphlet, 159 kinds of birds nest along the Blue Ridge Parkway, and dozens more migrate through it. 130 species of trees, 1600 kinds of plants, and 74 kinds of mammals (including bears) live here. Near one of the gorges, a sign indicates that 25 species of native ferns inhabit that area.

More than 50 species of threatened or endangered plants occupy terrain around the Parkway, so tread respectfully.

Among the oldest land formations on earth, the Appalachians got their start 1.1 billion years ago. From that time up to around 250 million years ago, European and North American tectonic plates collided, pushing up this mountain range that stretches from Pennsylvania to Georgia.

The Appalachians once were as high as the Rocky Mountains, but erosion slowly reduced their elevation. Now, the tallest mountain east of the Mississippi River is Mount Mitchell, reaching 6684′, near milepost 350, west of Old Fort NC. These cooler mountain tops support evergreen spruce-fir ecosystems, also found in the northern United States and Canada, while mixed hardwood forests occupy the lower elevations.

As rivers and streams shaped the surface of the land, pockets of territory became isolated from each other. Smaller “niche” ecosystems evolved, each with its own assortment of organisms. Geographic isolation and a great deal of time are the primary drivers behind speciation. One kind of salamander might inhabit a particular streamside location, but not occur anywhere else in the world, not even over the next ridge.

 

From the first superintendent of the Blue Ridge Parkway, Stanley Abbott:

“A parkway like Blue Ridge has but one reason for existence, which is to please by revealing the charm and interest of the native American countryside.”

Modern living continues to extract more land for housing, transportation, and commerce. But, with conservation of natural habitats, the National Park Service has protected vulnerable ecosystems for wildlife and preserved the history and character of the region for all to see.

 

 

If you’d like to read another article about gristmills, this one at The Farm In My Yard describes one that is still working in North Carolina, and dates from pre-Revolutionary War days: The Old Mill of Guilford. (Try their gingerbread mix!)

 

 

2020: The Year That Wasn’t?

 

pumpkin pie

Kim’s pumpkin pie.

Well, it’s almost over. We have the holidays to look forward to, right? Oh wait; here, we can’t gather indoors in groups numbering more than 10… Some areas are discouraging any kind of indoor celebration. I wonder what most American families will do.

There will be turkey roasting in the oven while freshly baked pumpkin pies cool on the counter. We’ll celebrate Thanksgiving (400th year since the Mayflower) and Christmas, although new traditions—new ways of gathering—might be born. (With respect due the native Indian cultures, I acknowledge that not everyone celebrates this day.)

How will your holidays look different this year?

Such misery this pandemic has caused many millions of us: jobs lost, loved ones lost, businesses closed, weddings postponed, school children missing out. The good news on the radio this morning announced another pharmaceutical company that has developed a vaccine for the virus. If it’s safe and effective, sign me up.

If all we can do is gather outdoors, then so it shall be. No problem; I’ll gather the camera and some snacks, and be off to some not-too-distant location…somewhere in nature, which, for me, never fails to rejuvenate.

This has been a difficult year for all of us, all around the globe. Good days are on the horizon, though, and I wish you happiness and good health. There’s still so much to be grateful for. Let’s celebrate that.

 

trees and sky, North Carolina

Northern North Carolina.

 

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This Is Why Fall Color Happens

Nov14

Updated 9/6/2024

 

 

 

forest, fall color

 

 

One of the most phenomenal transformations in nature occurs in autumn when leaves take on fall color.  

 

Deciduous tree canopies change from shades of green to the reds, oranges, yellows, browns, and purples associated with this time of year. A drive along the Blue Ridge Parkway, or even a glimpse out the window to the Japanese maple in the courtyard, elicits feelings of delight and wonder.

Equal to the spectacle unfolding in front of us, as we watch colors brighten from day to day, is the curiosity for an explanation. Why does fall color happen?

 

 

Plant Pigments and Fall Color

 

fall color

Looking up in Lincolnton NC.

 

It all starts with plant pigments, which give leaves their color.

Sandwiched between a leaf’s upper epidermis and the lower epidermis is a layer of cells called the mesophyll. The mesophyll is composed of the upright cells of the palisade layer, near the surface of a leaf, and the more loosely arranged spongy mesophyll. Both kinds of cells within the mesophyll contain chloroplasts, with chlorophylls “a” and “b”. Also present within the leaf is a network of vascular tubes—phloem and xylem—which carry water and nutrients between the leaves and the roots.

These chlorophylls absorb wavelengths from different parts of the spectrum. Chlorophyll a absorbs violet-blue and orange-red wavelengths, and chlorophyll b absorbs blue light. All plants have “a” but not all plants have “b”. In lower light levels, “b” more efficiently absorbs energy from available light and transfers that energy to “a”.

In autumn, as chlorophyll degrades into transparent compounds, the carotenoids become the dominant colors. Those pigments were there all along, but the green chlorophyll masked them. We don’t see the oranges and the yellows until the greens begin to die down.

 

tree leaves

Spring foliage on maple tree in the woods.

 

 

Chlorophyll

 

maple leaves, fall color

Oak leaves, at Mabry Mill, Meadows of Dan, VA (2020).

The green pigment is the familiar chlorophyll. We see it every day as plants grow and produce foliage. Chlorophyll, contained within a cell’s chloroplast, is responsible for manufacturing sugars during photosynthesis. Carbohydrates, made from oxygen and hydrogen in water, and carbon from carbon dioxide, permit growth and development of the plant. Chlorophyll is continually depleted and replenished throughout the season.

We see green leaves because most of the green wavelengths in light are not absorbed but are reflected instead. Chlorophyll pigments absorb primarily red and blue wavelengths.

Changes occur in late summer as days shorten and temperatures drop. Cells at the base of the leaf’s petiole, where it attaches to the stem, begin to cut off the vascular system. Water and nutrients no longer move freely between the leaves and the stems. Production of new chlorophyll stops, revealing the yellows and oranges. Sometimes the leaf veins are the last parts to change color and remain green as the rest of the leaf turns color (photo, above).

 

 

Carotenes and Xanthophylls

 

yellow fall color, maple in charlotte nc

A maple tree in Charlotte NC.

 

Carotenoids are composed of xanthophylls and carotenes. These are the yellow, orange, and brown shades seen in plants and animals—daffodils, corn, buttercups, bananas…and canaries, egg yolks, shrimp, fish, and flamingos. These pigments absorb wavelengths from the blue and some of the green parts of the light spectrum, which chlorophyll can’t absorb efficiently.

Xanthophylls and carotenes protect foliage from oxidative stress (cell damage) during photosynthesis. When the tree is exposed to strong sun, carotenoids absorb excess energy from excited chlorophyll molecules and release it as heat. In autumn, carotenes protect leaves as the nutrients are withdrawn from the leaves to the stems. The tree will re-use these nutrients when new foliage emerges in spring.

Beta-carotene, lycopene, lutein, and zeaxanthin are more carotenoids, present in leafy greens, fruits, and vegetables. These pigments are good for plants and for us, too—in squash, sweet potatoes, tomatoes, colorful ripe peppers, carrots, oranges, apricots, and grapefruit.

Between 15 and 30% of tree species have yellow or orange fall color. Trees that turn these colors include hickory, ash, redbud, yellow poplar, birch, aspen, black cherry, sycamore, maple, fringe tree, cottonwood, sassafras, Parrotia, pomegranate, alder, ginkgo, witch hazel, and Katsura.

 

orange fall color, lincolnton nc

Lincolnton NC.

 

Red twig dogwood ‘Arctic Fire’ and yellow-twig dogwood ‘Flaviramea’ stems turn color in cold weather and good sun. Cut back the plants in late winter, almost to the ground, to encourage a multitude of young twigs that will take on color later that fall.

Brown is often the color of cell walls and can appear in the absence of other pigments. Sometimes, leaves turn brown without turning color as a result of an early freeze. A Japanese maple that normally turns red in autumn, for example, can turn brown when the temperature suddenly plummets. Also, a tree that has been cut down in late summer or fall will turn brown instead of displaying its usual fall color. More on that later, under marcescence.

 

 

Anthocyanins

 

red fall color, crape myrtle

Fall color of crape myrtle, Cane Creek Park, Waxhaw NC.

 

What about the red colors? Unlike the yellows and oranges, the red pigments, called anthocyanins, are produced in the sap when sugars break down in bright light.

This happens after some of the chlorophyll has degraded in autumn and as phosphate levels decrease. Phosphates break down sugars manufactured by chlorophyll in the summer in order to carry out cell activities. However, in the fall, phosphates and other nutrients move from the leaves to the stems.

You might notice that in some years, the red colors are more vibrant than in other years. Rich red colors are visible when anthocyanins are produced in greater quantities. Bright sunny days, adequate soil moisture, and cool but not freezing temperatures foster the blazing displays we look forward to each year. 

 

berries

Edible berries with high levels of healthy anthocyanins.

 

Nutritionists encourage us to “eat all the colors” of vegetables, greens, and fruits. Anthocyanins, among the most powerful antioxidants, are found in many fruits and vegetables, including apples, cranberries, blueberries, strawberries, blackberries, cherries, grapes, plums, red cabbage, and red lettuce.

Carotenoids can combine with anthocyanins to form deep orange, scarlet red, and bronze fall colors.

In temperate regions, about 10% of the trees turn red or burgundy. But the percentage can be as high as 70% in areas such as New England. Some plants with predominantly anthocyanin pigments include maple, oak, sweet gum, tupelo, sourwood, dogwood, cherry, and persimmon. Purple-leaved cultivars of smokebush and redbud turn deep red in autumn.

 

 

Variety Selection in Your Landscape

 

burgundy fall color, Japanese maple with lantern

Certain varieties of Japanese maple display great color in summer and again in autumn.

 

When choosing shrubs and trees for your landscape, be sure to ask the nursery about fall color. There could be several cultivars within a species, each with a different color in autumn.

Japanese maple in fall color, new gardens

Japanese maple.

Japanese maple (Acer palmatum), for example, comes in many varieties. Red-leaved cultivars of this tree seem to be the preferred choices among customers. Foliage that remains mostly red all summer will gradually deepen to a rich reddish burgundy. And then it suddenly looks as though the plant is on fire, turning bright red. On the other hand, green-leaved cultivars can be multi-colored in the fall, or rich orange, or sunny yellow. It just depends on the cultivar.

If you’re looking for a specimen tree, and fall color is a factor, visit garden centers and public gardens in autumn when the trees show fall color. Research the full botanical names (Genus, specific epithet, and ‘Cultivar’) of the varieties you like.

This is not a guarantee, however, that young potted trees will have the same fall color as established trees. Plants in nursery pots can behave differently than plants in the garden, so take that into consideration.

 

 

Fall Color Might Depend on Weather

 

parrotia persica, reddish fall color in snow

Parrotia persica in the snow.

 

Seasonal weather conditions also affect a tree’s fall color. In the Maryland garden, a Parrotia persica grew in an island bed. The leaves of this witch hazel relative often turned a bright yellow color. In other years it was amber-gold, and, more rarely, salmon-red.

Prolonged mild fall weather also affects the display. That Parrotia (photo, above) occasionally held its leaves until December. Many oak species keep their orange, russet, rich red, or brown leaves through early winter before shedding them.

Red fall color is particularly dependent upon weather conditions. In 2018, trees that normally turned brilliant red were rather dull here in Charlotte. The heavy rains, high winds, and overcast weather did not promote the production of anthocyanins.

 

 

Hormones and Abscission

 

Abscisic acid (ABA), produced in terminal buds, slows growth and signals the plant to produce bud scales that protect the buds over winter. ABA is also produced in the root system and is translocated to the leaves during drought in the growing season, signaling the leaves’ stomates to close. This reduces transpiration, conserving water content in the plant.

Hormones produced in leaves and in the tips of twigs influence development of the abscission layer. This layer is a few cells thick, characterized by short cells with thin walls, and sits between the base of the leaf stem (petiole) and the twig. During the growing season, higher levels of auxin regulate the influence of ethylene, two hormones, resulting in the leaves’ ability to remain attached. Auxin levels fall in autumn, however, exposing cells in the abscission layer to the effects of ethylene, which promotes leaf detachment.

Cells between the petiole and the twig are differentiated, disintegrating on the leaf end and depositing lignin and suberin on the twig side. This layer of cells is weakened, causing the leaves to fall off by their own weight or with help from wind and rain. Enzymes, such as pectinases, help the process by breaking down cell walls.

Remaining on the twig is a leaf scar, with remnants of vascular strands. Over several days, lignin (tough woody tissue) and suberin (corky bark tissue) will seal the fresh leaf scar, protecting it from infection and desiccation.

 

 

Marcescence

 

beech tree, winter

Beech tree.

 

Oaks (Quercus spp.) sometimes remain in brown leaf until early spring. Beech trees (Fagus grandifolia) can be spotted in the winter forest by their tan leaves dangling from the branches. Leaf retention through winter is called marcescence. The reason for this trait is open to speculation.

 

Nutrient Release

One theory claims that, by holding onto its leaves until new foliage is about to sprout, those newly fallen leaves will stay near the tree’s root system instead of blowing away in the winter winds. Since they have yet to begin decomposition, the nutrients locked inside the leaves will be released at a time when they can benefit the tree—when growth resumes in spring.

 

Browsing Animals

Another theory indicates that browsing animals are less likely to feed on marcescent twigs. In studies where deer were presented with both marcescent twigs and leafless twigs, they chose the leafless twigs.

 

Weather Abatement

Maybe the dead leaves help slow down fierce winds, protecting the buds from drying out. Even better is the accumulation of snow, as in the photograph (above) of a beech tree, decreasing exposure even more.

Another possibility is the protective shade cast by marcescent twigs on thin-barked trees, such as beech (photo, below). Large differences in temperatures, between night and day, can damage tissues on the south or southwest side of the trunk. Frost cracks and sun scald can be minimized when the trunk is partially shaded by brown leaves during the warm hours of the day.

If cracks occur, callus tissue will seal them, and healthy bark will compartmentalize the wound. There’s no need to paint it with “wound sealer” products. And never fill the cracks or hollows with concrete or dump rocks and debris at the base of a tree!

When a severe early frost suddenly kills a tree’s foliage, the abscission layer would not have had enough time to mature. Consequently, leaves can cling until those cellular changes occur. Young oak trees might exhibit this feature, but it often disappears with maturity. Sometimes only parts of the tree have leaves that cling.

You might have noticed that trees felled in the summer often hold onto their brown leaves.

 

beech tree marcescence

Beech tree in winter, Charlotte NC.

 

 

Why Do Leaves Fall Off?

 

For a plant to keep its leaves all year long, resources would have to be consumed at a time when they are less efficiently gathered. When light levels are less than optimal, and cold temperatures suppress metabolic processes, it’s easier for the plant to reabsorb nutrients and drop leaves. Water loss, insect predation, foraging animals, and damage from ice, snow, and high winds are some reasons why it just isn’t worth staying in leaf through the winter. The cost is too great.

pine needles, in fall

Pine tree with aging needles.

Conifers, on the other hand, have adapted to those conditions, and are able to photosynthesize all year. But they do slow down in cold weather. And the sticky sap in some species (pines, spruce, fir, and others) effectively fends off animals and most insects.

Evergreens drop some of their foliage each year; needles don’t cling forever. Some homeowners are alarmed when they see a large percentage of brown needles fall to the ground. That’s normal, as long as the tips of the stems remain green. A pine needle carpet is an effective mulch.

 

 

Protective Red Fall Color

 

Scientists have long speculated on the merits of anthocyanins—the red, blue, and purple pigments. Those adhering to the Photoprotection Theory claim that anthocyanins protect leaves from harmful effects of light. This pigment also helps the tree absorb nutrients more efficiently in cooler conditions, before leaf drop.

mustard greens 'Miz America'

‘Miz America’ mustard greens and other brassicas.

Coevolution Theory claims that insects avoid feeding on leaves high in anthocyanins. The red fall foliage color signals them to stay away, but red berries signal birds to come and feast. (***Update***: Growing many flats of colorful fall greens illustrates this point. Among brassicas [mustard, kale, broccoli, cabbage], the deep reddish burgundy ‘Miz America’, one of the mustard greens, is entirely free of damage from caterpillars that ravage green varieties in this group. 10/7/2022)

Dogwood trees, hollies, barberry, and pyracantha have red berries that attract birds. After consuming them, the animals help distribute the seeds. Poison ivy has whitish berries that birds eat, but its foliage is fiery red, signaling birds to come around.

 

fall color in red berries of winterberry

Fall color in berries of a dwarf winterberry, Ilex verticillata, at Freedom Park, Charlotte NC.

 

Red colors in some species of maple trees are produced by a different metabolic process than through chlorophyll breakdown. These anthocyanins aid in preventing competition with the tree’s own offspring by stunting the growth of saplings trying to grow nearby. This is one type of allelopathy.

 

 

But Only Part of the Tree is Turning Color

 

fall color

 

You might have noticed that a portion of a tree is prematurely turning color while the rest of the tree is still green. I’m not referring to an even coloring at the ends of branches, but rather to the one branch that is conspicuously different in color from the rest of the canopy. That branch is stressed…

  • on the side of the tree where the roots are exposed to hot sun and poor, dry soil, such as on a south-facing slope (northern hemisphere).
  • from root compaction.
  • due to root disturbance, from working in the soil under the tree, severing roots.
  • because it’s heavily shaded and not contributing to photosynthesis.
  • from the tree being coppiced, or cut back to the ground. As several stems regrow, the dominant ones interfere with the others. Weaker stems will show early color and die.
  • due to girdling roots. Maple trees are notorious for this. Look for and sever a root that crosses over the base of the trunk. The trunk will try to grow over the root, but could end up being constricted. Look up from that point, and you might see branches that are developing early fall color. One indication of a girdling root is the absence of an even flare all around the base of the tree. One side of the trunk will look flat where it enters the ground.
  • from clotheslines, hammock ropes, or other items tied around the trunk or branches, eventually girdling the stem.
  • where lightning or physical damage stripped bark off the side of a trunk, killing parts of the tree above the damage which no longer receive water and nutrients.
  • from insects and diseases causing disruption in the flow of water and nutrients, affecting parts or all of the tree canopy. This can happen at the base of a leaf, a twig or branch, in the trunk, or in the roots.

 

 

Fall Color and Species Distribution

 

red fall color in maple tree

Red fall color in a maple tree, Lincolnton NC.

 

Some parts of the world are known for their fall color. Southern Canada, parts of the northern U.S., Scandinavia, northern and western regions of Europe north of the Alps, the Russian Caucasus region, Japan, parts of China, the Korean peninsula, Argentina, Chile, southern Brazil, and New Zealand’s South Island are some.

Certainly, there are pockets in millions of places around the world with absolutely dazzling fall displays! One option is to create your own by including in your landscape a few specimens with spectacular fall color.

In this country, changes in color begin as early as September in the higher elevations of the Rocky Mountains, far north Minnesota, and upper New England (far north New York state, Vermont, New Hampshire, and southwest Maine). Southern states, part of the Atlantic coast, and the California interior between mountain ranges begin their autumn displays in November. Check out this map, where you can see how fall color progresses throughout the country.

 

 

Speaking of Cold

 

North America is home to a diverse habitat of 800 species of trees, including 70 oaks. Northern Europe has fewer—51 species, 3 or which are oaks. These numbers do not include cultivars of the species. One thing scientists can agree on: they can’t agree on the number of tree species inhabiting the planet. Some say the number is 10,000, and others estimate over 100,000 species.

During the Ice Ages, North American tree species in southern regions and along the north-south mountain ranges were spared extinction caused by glaciers. As glaciers expanded from the north, trees were able to find refuge farther south of their original range. This took place over thousands of years. The last Ice Age occurred from 18,000 years ago to approximately 12,000 years ago.

However, in Europe, glaciers covered a larger area of land. The Alps acted as a massive barrier to species trying to retreat toward southern latitudes. Those trees were cornered, and then covered up by mile-thick sheets of ice, causing mass extinctions. This explains the disparity in the number of tree species between North America and Europe.

At the height of the last Ice Age, about 18,000 years ago, glacial ice covered one third of the planet’s land surface. Today, about 10% of the land is covered by ice.

 

 

Fall color is nature’s last hurrah of the season. 

 

I hope you’ll consider planting trees and shrubs that have brilliant autumn color. If you’re not planning to do any landscaping, you can still enjoy the colors of autumn by visiting parks and public gardens, or by taking a leisurely stroll through the neighborhood. Maybe it’s time for a road trip. Don’t forget the camera!

 

fall color

Love it.

 

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