Earthworms...The Canaries Of Your Landscape

Weatherproofing Your Landscape is all about the health and weather-tolerance of your trees and shrubs. So you might be wondering: What do earthworms have to do with that? Well, it happens that these little squiggly creatures have a lot to do with your big anchor plants.

For one thing, earthworms are the canaries of your landscape. If you dig a hole a cubic foot deep and don't find at least 5 plump and lively earthworms, you can bet that your soil lacks the organic matter and microbial action necessary for healthy plant growth—be it pansies or a mighty oak tree.

Here's the scoop on why you should care:

Earthworm castings (poop) have a nitrogen-phosphorus-potassium (NPK) rating of 5-5-3. Castings sell for up to 25 bucks a pound. For every three earthworms, your soil gains around a pound of this high-grade organic fertilizer each year. Worm-friendly soil can host up to 25 earthworms per cubic foot. Do the math.

As if that weren't reward enough for treating these guys with royal respect, earthworms help neutralize soil pH by oozing calcium carbonate. (I guess you could say they're the Rolaids of the garden.) And their miles and miles of tiny burrows allow air, moisture, surface nutrients and roots to penetrate deeply into the soil. They also treat lawn thatch and harmful nematodes like Thanksgiving dinner.

Ya just gotta love 'em.

So here are some things you need to know about your little subterranean buddies.

• Earthworms have the sunlight tolerance of Dracula, coming out only at night to grope for food. (They collect on the surface and haul everything downstairs.)

• They like soil temperatures of 50F to 60F degrees. In the heat of a summer day or during winter, they burrow deeper to find that temperature.

• Move a worm to unfavorable soil, and it'll die, pronto.

• Earthworms have a taste for grass clippings and shredded leaves, as well as banana peels, coffee grounds, composted cow or rabbit manure, and ground eggshells. (Steer clear of pickled foods and salt.)

• When adding a powdery substance to the soil, suspend it in water first, or it'll desiccate worms.

• Even if you don't have earthworms, you probably have them. Worm eggs can remain dormant for long periods...until you create a favorable habitat for them.

• With earthworms, you don't need to till. In time, they will burrow up to 6 feet deep, turning the soil as they go.

• Earthworms breathe through their skin, so any chemicals used in the landscape will either repel them or kill them outright.

The best earthworm habitat I've ever seen was beneath a bird feeder outside my living room window. Over a period of months, birds left a layer of sunflower-seed hulls several inches deep. I could rake my fingers through the moist hulls and stir up masses of huge, fat, wriggly earthworms.

If only the robins had known...

Coming Friday...Holiday Gift Ideas!

In response to requests, I'm putting together Weatherproofing Your Landscape holiday gift ideas for folks who want to make sure friends and loved ones get on the road to more weatherproofed landscapes. (And you just might want to add some of these items to your holiday wish list for yourself!)

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.