Leaving Leaves Alone

When I was a kid, autumn was always accompanied by the Currier & Ives aroma of burning leaves. Before the age of leaf bags and curbside yard-waste pickup, that's what homeowners did with the huge piles of leaves dropped by their trees.

I miss that smell. But I've come a long way since those days. Besides appreciating clean air in the fall, I've also come to know that lighting a match to leaves is akin torching pure gold.

Fallen leaves contain up to 80 percent of the nutrients that a tree has absorbed during the growing season. If allowed to decay on the ground, they return this store of nutrients to the soil, where they are reabsorbed by roots and channeled back to a new season of growth.

Leaves also are an incredibly rich source of organic matter that helps soil retain nutrients and moisture, while keeping pH levels in balance. And they are a favorite food of those often unsung heroes of the garden—earthworms (which will be covered in Wednesday's posting).

But a season's production of leaves from a single large tree can amount to a formidable pile. And if you live at the south end of a cul de sac, as we once did, a stiff north wind could gift you with most of your neighbors' leaves, as well. (I learned to accept these freebies with glee!)

So how do you manage these mountains of gold?


Flowtron LE-900 with tilt stand

  
You shrink the mountain.

Shredding leaves can reduce the bounty to 1/16th of its original volume. Shredding also solves another problem: if left whole, leathery leaves such as oak can take years to decompose, meanwhile creating a barrier to moisture reaching the soil.

When it comes to shredding leaves, you have a lot of options, both gas and electric. My sister, who has two large trees in her backyard, simply runs over the leaves with her electric mulching mower. She lets the shredded leaves remain in place, thus eliminating the added chore of raking.

There are any number of gas or electric free-standing shredders—some of the heavy-duty variety also chop small branches, which can be handy during spring cleanup or following a storm. This method requires raking, as well as  stoop labor as you pick up armloads of leaves and feed them into the hopper. But that's terrific exercise almost guaranteed to reduce the waistline.

We use a hand-held leaf vacuum, with a hose that runs to a hood, which fastens onto a garbage can. (You can simply let the leaves blow out the back end of the hood onto the ground, but that makes for a pretty messy situation.) This works most efficiently if the leaves are raked into a pile first, then vacuumed up. But there isn't any stooping.


Patriot Pro-Series leaf vac

Or you could go with a walk-behind leaf vacuum that sucks up and shreds leaves, then deposits them into an attached bag. No raking or stooping—except when clearing leaves from beds.

Of course, if you have a large property with lots of trees, you might want to go with a riding mower with a mulching/bagging attachment. No raking or stooping—or even walking.

So there is a leaf-mulching system to suit just about anyone's pocketbook or energy level.

Once you have your leaves shredded and tidied, you can spread them directly onto garden beds (no more than 2 or 3 inches deep...and rake them in lightly). Or you can corral them in a wire cage or leaf bags for later use, either during winter or during the next growing season.

Shredded leaves make an excellent, nutritious mulch for summer (keeping soil cool while maintaining soil moisture) or winter (piled around tender plants to provide insulation against the cold). Note: you might need to top with a thin layer of cedar mulch, straw, or other weightier material to keep them from blowing away.

Most of all, leaves returned to the soil are able to play their vital role in your tree's great annual cycle of life, from birth to rebirth. 

Since You Asked...Sandra Dark About Buying Stock From Big Box Stores

In much of the country, the fall tree and shrub planting season is still in progress—and so are the questions I'm asked about buying stock from home improvement centers and other big box stores.

These high-volume plant outlets have become a major source for the anchor plants grown in landscapes across the country. As such, they are in many ways making an imprint on the quality and durability of urban forests—including the part encompassing your own backyard. This imprint can be either good or bad, depending upon how alert you are to both the up and down sides of shopping for live plants at the same place where you get your plumbing supplies, fishing tackle, and toothpaste.

So here are a few of the most important and frequently asked questions.

Q. How do I know if the store's trees and shrubs are of good quality?

A. To begin with, a store's living plants are only as good as its supplier—so ask who supplies the trees and shrubs. (You might hear, "Oh, the guy who knows about that stuff is off today." Wrong answer!) When you get the supplier's name, check them out online. Preferably, they are actually growers, and not just distributors that buy from unspecified nurseries and ship to retail stores.

(Note: Some stores sell last year's leftover stock that they buy from wholesalers and other retailers at a major discount. Even if you can buy one of these holdovers for a song, it isn't a bargain.)

But a major consideration is whether the store stands behind its plants 100 percent, unconditionally guaranteeing that your new tree or shrub will survive its important first growing season. (Save those cash register receipts!) Last summer, I saw customers returning dead trees and shrubs to home improvement centers across my community, after the plants were killed by a brutal heatwave/drought.

A. How do I find the best species for my landscape at a big box store?

Q. To be blunt, you often can't. For the most part, big box stores carry cookie-cutter trees and shrubs. These same species are seen in new housing developments from coast to coast, as well as in shopping center landscapes. What community doesn't sport ubiquitous red-tipped photinias,  Bradford pears, and other species whose main claim to fame is that they are easy on the wallet?

But many big outlets also offer species that are highly suitable and desirable for your local conditions, such as drought/heat tolerant crape myrtles in the Southern Plains, or bald cypress on the Southern California coast. (In this age of extreme weather, tolerance of  conditions most common to your locale should be a top priority when choosing plants.)

So do your homework before shopping. Contact your local cooperative extension agent or local native plant society to find out what species are suitable for the hot, dry, wet, windy, semi-shady or other conditions in your specific landscape. Then shop for only those species and varieties. If the big box stores don't carry what you're looking for, refuse to settle for what they have.

And don't depend on the advice of sales help in these stores! I have yet to come across a genuine horticulturist working in a big box establishment...but find that many of the untrained workers are very generous about handing out misinformation. So cross-check everything they tell you with authoritative online sources or your cooperative extension horticulturist.

A. How do I know if an individual plant is of good quality?

Q. First, check for signs of disease or infestation. (I once walked into a greenhouse that was overrun by aphids, and another where half the plants were coated with powdery mildew.) Take a close look at the stems and undersides of leaves.

Make sure the plant is symmetrical, and doesn't have a "bad" side caused by branch loss or growing too close to other plants.

Look for major stems that have been lopped off—a sign that the plant might have suffered damage, or was last year's stock that has been pruned back to keep it at a marketable size in its current pot.

Take hold of the stem near the base and gently rock the plant. If it shifts in the pot, then it's a holdover that has been repotted for quick sale. Such a plant is not a bargain at any price.

Finally, if you are looking for a flowering shrub that comes in a variety of blossom colors, wait unti the bloom stage before making your purchase. It isn't uncommon for such plants to be mislabeled, so you could end up with a pink crape myrtle instead of white.

And speaking of crape myrtles: after searching nurseries for two years, I found cinnamon-barked Natchez crapes at a big box home-improvement center last summer. I carefully picked the best in the bunch, and planted it on a 100+ degree day during an exceptional drought. The crape thrived, far exceeding my wildest expectations.

So you can fill your landscaping needs at a big-box store if you do your homework, shop wisely, and keep your eyes and mind wide open.

Where do you buy most of your trees and shrubs? At a big box store? A local nursery? Mail order?

Treacherous Beauty

I remember the good old days when, during long walks in the summer, I would pause to admire (covet) wild trumpet vines growing along the country roadsides. Often, a rubythroat hummingbird would be face-deep in a brilliant orange blossom, drinking in its rich nectar. I would think, I'll stop by in late summer and gather some of the seed pods...or maybe find a small vine to transplant next spring. But years rolled by, and I never got around to it.


Trumpet vine (Campsis radicans)

Then some unseen bird made my wish come true by depositing seeds on our property. I can't tell you how thrilled I was to spot a distinctive splash of orange along the treeline in front of our house. I grabbed a camera and commemorated the moment a picture.

The pleasure didn't last. All too soon, we learned why this vine with its glorious blossoms is called a thug.

Our perky little volunteer burgeoned with the rampant enthusiasm of kudzu. Its root system produced vast underground networks (some gardeners who have tried to eradicate trumpet vine claim the roots grow up to 40 feet deep!), and sent up new sprouts that quickly grew into astonishingly robust invaders that rivaled the Mongol Hordes. Attempting to pull up the vines was like trying to pull up a sewer line: the linkages just kept going and going.

We tried mowing, but that only seemed to encourage new sprouts. Neighbors who had been gifted with similar "volunteer" trumpet vines grew so desperate that they set aside their organic practices and tried dabbing herbicides on the leaves. Their trumpet vines laughed.

You might think this was much ado about nothing—after all, trumpet vines are gorgeous, and hummingbirds adore the blossoms. But trumpets can be deadly. They develop woody stems that naturally want to grow up fences, walls, telephone poles...and trees. Grown on a wooden fence, it will insinuate itself between the boards, where it will proceed to slowly tear the fence apart. Allowed to grow up a porch post, it will probe through the tiniest openings until it finds a way inside the eaves and attic of your house.


Trumpet vine growing up an oak tree.

Allowed near a tree, it will shoot up the trunk and fill the canopy with its foliage and blooms. And as the years go by, the stems will grow thicker (I've seen them as big around as my wrist) until they can begin choking the life out of branches.

Trumpet vines aren't alone in their ability to damage or destroy trees. Climate change is resulting in more carbon dioxide in the atmosphere—a boon to vining plants. In the past, vines such as Virginia creeper, honeysuckle, Boston ivy and wild grape could be kept within the bounds of reason. Now they run amok, growing at rates unheard of before. I've even seen wisteria blooming in the tops of tall cottonwoods.

Vines don't have to produce powerful woody stems to do severe damage to trees. Years ago, we had a stand of young oak trees in which a wild grape vine grew. Before I noticed what was happening, the leafy vine had grown to the top of the canopy, spreading in the sunlight and shading out the tree foliage. Deprived of their ability to photosynthesize, the trees died.

Even vine-stressed trees that survive can be so weakened by their unwanted "guests" that they are left vulnerable to extreme-weather events. During drought conditions, these vines drink up scarce water resources that could have gone to the tree. And vine-shaded canopies produce less of the energy that a tree needs to heal injuries or resist pests and diseases.

So these days, I limit vines in my garden to annuals. And when I see any vine growing up a tree trunk, I'm quick to cut it off.

What experiences with "treacherous vines" have you had in your garden?

Raining Bullets: Severe Hailstorms

Forecast: Thunderstorms today, with a chance of large hail. Which reminds me...

One bright, sunny day, I was standing in the front yard innocently picking bagworms off an arborvitae, when I heard something go plop behind me. I turned, and found a golfball-size hailstone lying in the grass. Just one. I checked the sky, and the only cloud was a modest snow-white thunderhead miles away.

If that hailstone had landed on the roof—or my head—it would have made a good-sized dent.

But when it comes to hailstorms, it isn't always the size of the hailstone that counts, as much as the volume...and the delivery system. We found that out last spring.

Late one quiet afternoon, my sister called, half shouting, wanting to know if the storm had reached us yet. Barely able to hear hear her over the roar on her end of the line, I thought, "What storm?" And suddenly a wall of pea-size hail hit our house, driven in a horizontal wave by 60-90 mph winds.

For more than 20 minutes, the hail hammered away, first from the west before turning around and coming back at us from the east. For more than 20 minutes, we couldn't see out the windows. For more than 20 minutes, we felt utterly helpless...as one often does during an extreme-weather event.

When the storm finally ended, the yard looked like a giant salad bowl, ankle-deep in green leaves. The trees had been stripped of a good two-thirds of their foliage. "Hail fog" caused by ice lying on warm ground drifted around until almost noon the next day, making some neighborhoods appear to be on fire.

The dramatic tree defoliation was community-wide. (As for roof damage, one local roofer reported that he had two years of work lined up as a result of the storm.)

But what about those trees? I hoped they would refoliate from secondary buds. But immediately after the storm, a brutal heatwave set in that further stunned landscapes already stressed by a long-running drought. So the trees stood partially denuded all summer long, many with barely enough leaves to keep them alive.

In retrospect, the defoliation might have been a partial blessing. With fewer leaves to support, the trees could get by on less water in record-setting drought conditions. But we missed the shade during the brutal summer, and still worry that the battered trees won't make it through what is predicted to be a dry winter ahead.

All in all, I've gained a greater respect for the awesome power of hail. There is little you can do to prepare a landscape for such a hit. The best we could do all summer was deep-soak the trees on a regular basis—and keep fertilizer away from their root zones. [For information on fertilizing damaged trees, check out To Feed Or Not To Feed, That Is The Question.] And with a dry winter predicted, you can bet I'll be dragging out soaker hoses while togged out in cold-weather gear.

Since You Asked...The Davey Tree Expert Company About Surface Roots

My Japanese laceleaf maple tree has surface roots that just dare me to trip over them or clip them with the lawn mower. And my big American elm has a girdling root. You might have the same problems and wonder, as I have many times, whether exposed or girdling roots pose a serious threat to your valuable trees.

So I contacted Nicole Wisniewski at The Davey Tree Expert Company. Nicole consulted with company arborists, and now we can clear the air.

The Davey Tree Expert Company

Q. What are the common causes of exposed tree roots?

A. There are several reasons for surface tree roots. Some species, like maples, are simply more prone to this than others. Older trees also tend to show more roots than younger trees. But this often happens when there's little or poor soil in the area, poor drainage, or as a result of poor planting practices.

Q. Do exposed roots present special dangers to the tree?

A. While surface roots may be unsightly, they rarely pose a threat to the tree.

Q. What should be done about them?

A. There's usually little you can do about exposed tree roots. Arborists don't advise trying to prune or cut away any of these roots, to avoid damaging the tree itself.

But if the tree is planted too close to a home or other structure, or if roots are causing damage to a structure, you may want to consider having the tree removed or transplanted to prevent potential or further damage. Professional arborists can assist in this.

Adding soil to the exposed root area may help cover exposed tree roots, but this might be short term. As the tree grows, so will the roots, and it's only a matter of time before they resurface. Also, soil fill over a root system will reduce oxygen availability [to roots].

Q. What should be done about exposed roots that have been damaged by mowers or foot traffic?

A. A professional arborist can assess the tree to determine if there has been significant damage, and help root-prune to preserve the tree and reduce tripping hazards.

Q. What should be done about "root strangling" (roots growing atop other exposed roots)?

Girdling root on an elm.

A. Girdling roots are roots that grow around other roots or trunks, putting pressure on them—thus, "choking" and compressing the water and nutrient-conductive tissues.

Recommendations vary with respect to the value and practicality of removing girdling roots. For instance, girdling roots may be supplying a significant part of the tree with nutrients and water, and removal of these roots may further stress the tree.

A professional arborist can assess the status, and provide solutions, using proper techniques to remove some roots if necessary. When dealing with girdling roots, sooner is better [than later] to prolong the life of the tree.

The Life Expectancy of a Tree

I can go out into my backyard and put my hands on a big post oak tree that's been growing in that same spot since before I was born. Then I can step over about 40 feet, and lean against a pine that is perhaps half that old, though the two trees are the same height. In the best possible world, my oak tree will be around for a hundred years, and can be expected to outlive its neighbor by a quarter of a century.


Long-lived eastern red cedar.

But just across the fence stands an eastern red cedar—a wildly invasive pest that has taken over millions of acres of  grasslands in the Southern Plains, and is choking out vast areas of native deciduous woods. Hypothetically, that cedar could outlive both the post oak and the pine by a good 700 years.

Obviously, when it comes to trees, there doesn't always seem to be a lot of justice in the age distribution of different species.

So how do the trees in your own landscape measure up? Have you ever even thought about how long you can expect your valuable anchor plants to continue to fulfill their important roles? Perhaps you should. Because a  desirable long-lived specimen might be well worth the cost of restoration if it is damaged by an extreme-weather event, while a short-lived tree might warrant removal and replacement (preferably, with a long-lived species).

The ubiquitous Bradford pear is a classic example of a remove-and-replace tree, should it become seriously damaged or simply begin to "age out." The life span of a Bradford pear is 15 to 25 years—and the last five years are apt to look sad indeed as its lollipop shape tends to open out and spread. So...the first five years are devoted to establishing itself and taking shape, followed by a maximum of 15 years in good-looking prime time (if a severe-weather event doesn't substantially shorten that period—a distinct possibility), ending by at least five years of decline.


Short-lived Bradford pears.

If it seems that I spend a lot of time dissing Bradford pears, well, I certainly do. To that, I could add the river birch, despite the fact that the species' "Heritage" cultivar was named 2002 Tree of the Year by the Society of Municipal Arborists. In 2007, I saw many, many river birches destroyed by an ice storm in my community. Five years later, many more remain out there in landscapes, their severely damaged crowns still sporting visible signs of damage.

In this age of increasingly extreme weather, planting a tree that can't "take the heat" (or ice or wind or flood or whatever your region dishes out) makes about as much sense as packing a bikini on an expedition to the South Pole. A little forethought can save you from a lot of grief.

Every part of the country has its rogue's gallery of tree species that are vulnerable to the specific forms of extreme weather common to those areas. Some trees just don't have the structural habit or strength to stand up to the assaults that landscapes across the country are being subjected to these days.

So what does a tree's life expectancy mean to you and your landscape?

First of all, keep in mind that a long-lived species won't necessarily live out its full life span if  it is planted outside its desired growing conditions. And that means more than just its hardiness zone. You also need to take into consideration a species' soil and moisture preferences, as well as what extreme-weather conditions it can tolerate.

Over the ages, a tree species that is native to your area has evolved an ability to withstand most of the types of extreme weather likely to strike you landscape. (Tornadoes and powerful hurricanes are an exception— they have the capacity to uproot even long-lived native trees.) If these native species hadn't developed their weather-specific strengths, they could never had continued to survive and evolve the capacity to live very long lives.

So when I plant trees, I shoot for species that have a "normal" life expectancy of at least 75 to 100 years. These include oaks, maples and ginkgoes. Yes, these trees will outlive me. But I also know they will grace the places where I've lived for generations after I'm gone—a concept that I rather fancy.

Long-lived oak.

The benefits can be striking.

When the ice storm of 2007 struck, my heavily-treed neighborhood was hit particularly hard. Debris-removal trucks trundled up and down the streets week after week, hauling away shattered tree branches and trunks. The roar of stump grinders made pesky leaf blowers sound like wind chimes. But over on the next block, the sturdy oak shown at the right stood unscathed. The tree is probably about 40 years old now, and Nature-built for our heavy-duty weather extremes. With proper care, this tree should live on for generations longer.

You can learn the life-expectancy of your own trees—or that of a tree you think you might like to plant—by googling the species and "lifespan." For an overview of several dozen species, check out this site.

Then, before you buy another tree, pick up the phone and talk with your local cooperative extension agent or municipal forester (if you community has the latter) to find out if your chosen species is suitable for the growing conditions and extreme-weather events common to your location. (Besides longevity, you'll be wanting to know if your soil, drainage, hardiness zone, and other factors are compatible with your choice.

And don't be shy. It's perfectly okay to go out and hug your trees.

BLOG EXTRA! When Autumn Leaves...Pack With Snow

Wow. Just...wow. Right when you're all set to enjoy the colorful fall foliage, along comes a freaky autumn snowstorm of deep-winter proportions.

Of course, the results are predictable. Leaves hold onto snow, adding tremendous weight to tree branches that would otherwise shrug off the frozen stuff. The sound of breaking limbs reverberates through neighborhoods, accompanied by cold darkness as shattered tree parts bring down power lines. At last count, something like 3 million households and businesses have been left without power.

Clearly, Halloween has delivered all Trick and no Treat.

My agent, Gina Panettieri, reports from Connecticut that she has a tree in her swimming pool, and no one in the area has gas or hot water.

Courtesy Alexandra Owens

In New Jersey, American Society of Journalists and Authors Executive Editor Alexandra Owens has trees down all over her neighborhood, including in her own front yard where her Callery pear split down the middle. (The species is notorious for buckling under stress.)

There isn't much you can do to save large, leafy trees from damage when a storm dumps not just inches, but feet of wet, sticky snow. If you've taken preventive measures by pruning trees to create stronger branching habits, whether your tree then comes through unscathed will depend on how much of a weight lifter it's become.

Some tree species just naturally have branch angles better able to carry greater weights. Others—such as Alexandra's pear—don't.

But there is something you can do to help shrubs. Wade out in the snow with a broom and start brushing off the frozen stuff, beginning at the bottom and working your way up. Don't bat at it—just brush and lightly jiggle the branches. If the weight has already warped the shrub, it will often resume its proper shape over the next few days if branches haven't been broken.

Once power has returned to the area, the daunging job of cleanup begins...

This posting will be updated as other photos and stories arrive. And do leave comments on what the storm has done to your area!