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The Frugal Gardener: Winter Pruning, Part 1

The Rantings & Ravings of a Pruning Freak

Dave Cantwell —  March 9, 2013 — Leave a comment

“When’s the best time to prune?”
“Anytime!”

It doesn’t matter what season you’re in because there’s always something that can be pruned. You just have to know the plant, its growth characteristics, its best time for pruning, and what your intentions are for that plant as it plays into the whole of your garden design.

“Well, I don’t have a design. I just plant stuff. If it lives, great. If not, then what?”

It all starts with your vision for your garden. You’ve likely seen countless photographs of gardens, viewed television programs, and taken garden tours of your own. And each time you did that, something stuck with you and you want your garden to “look like that.” Maybe it was a particular plant, a color combination, or just realizing that, “Hey! This stuff actually grows in the shade!” These elements get stored in your mind — adding up to what you would want your garden to look like or feel like.

PHOTO: The Garden Wall in winter, looking south towards Dundee entrance ramp.

Willows and red twig dogwoods along the Garden wall next to the Edens Expressway

Maybe it’s a garden that provides a shady respite from the summer heat. Or an open garden theater that celebrates the hot, sunny days of summer. It can be loose and informal, or very tightly clipped into a classic formal garden. Whatever your style, the plants need to grow within the parameters of that design, and after the initial design and build phases, pruning is the most important tool that will keep your garden spot-on with what you envisioned.

The Basic Rules of Common Sense Planting

It’s important to remember that gardening happens in four dimensions — height, width, depth, and time. Plan for what the plants will be doing over time, like growing larger, taller, and deeper. Then, don’t plant something that will grow to 60-feet tall under a power line that’s 30-feet up. Do the math. And if the tag on the plant — assuming, of course, that it’s the correct tag — says that this tree will grow to 15 feet in diameter, don’t plant it 5 feet from something — like your house or driveway. Really. Yes, it looks nice and cute sitting there fresh out of the pot, and you take a picture of your toddler standing taller than the plant. Come back in ten years when the toddler is a kid and the plant is a real tree. Avoid the disappointment and frustration at the beginning — I’m talking about the tree. You’re on your own with the kid.

One overarching word of advice for your pruning technique is not to leave stubs or flush-cut. Most branches have a visible collar of folded bark at their base where the branch grows out from the supporting structure — a trunk, limb, or branch. This collar is all that needs to remain when the cut is complete. Leaving more than that, a bit of the branch for example, is a stub. You have a stub if you can hang your hat or your jacket from it. The plant will waste energy shedding this (plant’s version of a hangnail), and as it unevenly sloughs off over time, the site becomes an entry point for rot, disease, and pests. You don’t want that. And by flush-cutting this material, you make it even more challenging for the plant to close the wound. That’s what that little collar of material is — the plant’s built-in bandage. No need for petroleum products to close the cuts — these plants were created with their own internal first-aid system. Let them do their own thing. Just give them a good start and leave them alone.

Coppicing

So now it’s winter — dormant time. This is the best season of the year to perform the most radical cuts of all, short of cutting the thing down. But then again, you may want to do just that!

A willow before coppicing

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After coppicing a willow

Pruning willow

There comes a time in the life of some plants when cutting them down is exactly the right thing to do!

Coppicing is the horticultural practice of whacking down younger trees, virtually to the ground, leaving short stubs sticking out of the soil (it’s not dirt — you wash dirt off of your car or your dog or your kids). No need for them to be any longer than your finger. And be sure to use clean, sharp saws and pruners. Ragged cuts and tears only invite pests and disease by offering an easy port of entry. Life is tough enough — you don’t want that.

Primarily, coppicing is a technique used on trees to alter their growth habits from single-stem trees into multi-stemmed ornamentals, or more shrublike plants. Willows lend themselves handily to this practice, wherein a healthy, established young willow (Salix alba ‘Britzensis’) regrows over successive seasons into a more shrublike plant resembling a red twig dogwood. It works well when you want that look in an environment that’s too harsh for dogwoods, but in which willows can survive, such as winter salt spray from a road, or drying, frigid winter wind.

Rejuvenation

We can coppice shrubs, too. Take, for instance, the red twig dogwood, an old favorite. Over the years, the red becomes gray, the stems become overgrown and brittle, and trimming with shears or hedge trimmers over successive seasons creates a dense thicket of twigs on top with leggy, open stems at the bottom. It looks like an umbrella with extra handles and nothing like those pictures in the gardening magazines. There is good news — you can have a shrub that looks like it came straight out of a gardening magazine by midsummer this year! If it’s properly sited (sufficient sun, water, and drainage), and the roots are established and healthy, then this is the winter to coppice the shrub when it’s the most dormant. My general rule is to cut between Super Bowl Sunday and St. Patrick’s Day (yes, you can do this later, even after buds break — just not too long after). The healthy new stems will all grow back straight, shiny, and colorful — an exciting and welcome bright spot for next winter, which is the primary reason for planting red twig dogwoods — winter interest!

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Red twig dogwood in need of rejuvenation pruning

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Red twig dogwood pruning

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Note the darker stubs from last year’s rejuvenation pruning and how many stems have grown back.

When you opt for this process of going medieval on the plant, it actually spurs the complete, new regeneration of the entire plant above ground. Yes, at first it will just sit there, apparently doing nothing, and looking like a goner. But give it time. What you don’t see is the plant figuring out that it needs to develop new shoots, which will bud right out of the stubs you left behind. Just leave them alone and water the shrub if rainfall drops below 2 inches per week. And it’s always best to give it a couple of good, deep waterings per week rather than spotty, shallow daily passes with the hose or sprinkler.

You want the water to penetrate down into the root zone. If you had x-ray vision, you’d see the dense, rounded mass of roots extending beneath and around the shrub, and each root fiber poking around in the soil looking for water, nutrients, and oxygen. The spaces within the soil allow for the passage of these elements to the roots. Seeing the water percolating through the soil and into this zone may help you to better understand how plants grow, and enable you to more successfully address the plant’s watering requirements — especially now that you’ve cut it down! Forget what the neighbors might think, because you can rest assured that by the end of summer they’ll be envious of the new; perfectly shaped red twig dogwoods in your garden.

Stay tuned for more Frugal Gardening Tips on pruning next week.


©2013 Chicago Botanic Garden and my.chicagobotanic.org

Woodcut Opens…

And You'll Never Look at Trees the Same Way Again

Karen Z. —  January 23, 2013 — Leave a comment

In the Woodcut video of artist Bryan Nash Gill at work, there’s a moment that made me gasp: as Gill peels back and lifts the paper from a tree’s cross section that he’s printing on, three dimensions seem suddenly distilled into two, revealing the internal life of the tree. That first peek is profoundly intimate and thought-provoking — check it out here.

It took 1,022 wood "cookies," 3 people, and 3 blisters to install the exhibition's title.

It took 1,022 wood “cookies,” three people, and three blisters to install the exhibition’s title.

Woodcut opened this weekend, with 25 of Gill’s prints presented in Joutras Gallery. Each of the AV (artist variation) prints is made by hand: Gill sands and burns a crosscut of a tree, inks it, then presses paper onto the ridges and edges of the surface. Most of the salvaged wood—fallen trees, a telephone pole, a tree hit by lightning—was collected near his Connecticut studio.

Yes, you can count the tree rings in his prints—but look closely and you’ll also see the good-weather years and the bad…the scars and damage from age and insects…the patterns of growth and the checks of disintegration. The largest print (nearly five feet high) documents an aged ash tree—an especially poignant piece for us at the Garden, where emerald ash borers were discovered in 2011, and where we expect to lose hundreds of native ash trees in the next few years.

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The theme of salvaged wood influenced the design of the exhibition itself. In the entry hall, the show’s title is formed by 1,022 wood “cookies” cut from branches pruned at the Garden, then glued into place on the wall. The gallery benches were made especially for this show, milled by an on-site sawyer on World Environment Day (June 3, 2012). After curing, the boards were sanded, sealed, and mounted as bench tops by our carpenters.

Now available at the Garden Shop, Woodcut: Prints by Brian Nash Gill

Now available at the Garden Shop,
Woodcut: Prints by Bryan Nash Gill.

Mr. Gill honors the Garden with a print called English Oak, on exhibit with the cross section of the tree from which it’s made. The tree stood as one of a pair along the outer road here; it was removed after it grew into its neighbor, threatening the health of both. (The second tree regained its vigor after the removal.) Gill made just 18 original prints from the cross section; the prints can be purchased at the Garden Shop

January is a splendid month to learn about trees at the Garden. In conjunction with Woodcut, the School of the Botanic Garden has a terrific lineup of tree-related classes and workshops.


©2013 Chicago Botanic Garden and my.chicagobotanic.org

Updated: Snow Drought!

How to protect your trees and garden

Karen Z. —  January 14, 2013 — 3 Comments

There’s no doubt: it’s a snow drought, and records are falling like…well, like snowflakes should be falling.

  • Wednesday we broke the record number of days without a 1-inch snowfall (319).
  • Last weekend we broke the 1940 record of 313 straight days with less than 1 inch of snow on the ground.
  • Just 1.3 inches of snow (more near the lake) has fallen to date, compared to the norm of 11 inches.

It made us wonder: what does a snow drought mean for your garden?

To find out, we talked with Boyce Tankersley, our director of living plant documentation.

What Snow Drought Can Do to Your Garden

It’s easy to give snow drought the brush-off  (no shoveling! no scraping! no wet feet!), but it can damage your plants and affect the soil in your garden. The following can happen in a drought:

1. Moisture loss accelerates. “It’s the combination of no snow cover plus cold winter wind that does the damage,” Tankersley explains. “When there’s no snow, plants act like a wick in the soil, so the wind not only dries out the trees and shrubs, but also the soil they’re planted in.”  

2. Soil compacts. In a normal year, it rains in November, so the moist ground freezes as temperatures drop. Ice crystals form in the soil. As winter progresses, snow piles up, preventing wind from reaching the frozen moisture in the ground. With spring thaws, ground ice melts, creating air pockets and naturally looser soil. In short, Tankersley says, “winter is good for gardens.” Without that rain/freeze/thaw cycle, air spaces can’t form in the soil, so it collapses and compacts, requiring mechanical tilling to loosen it up again.

3. Plants get stressed beyond capacity. In 2012, plants endured an early spring with a late frost, followed by summer and fall drought, and now, snow drought. There’s a real risk of winterkill—the term used when plants succumb to winter conditions. “Check trees and shrubs for buds in early May,” Tankersley suggests, “especially non-natives like Magnolia soulangeana, which is particularly susceptible to winterkill.” Even well-established, old trees can succumb—forever changing yards and neighborhoods.

What You Can Do to Help Your Garden

On mild days when temperatures are above freezing, Tankersley’s strategies for home gardeners include the following:

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1. Mulch. Like a thick blanket, mulch holds in moisture and creates a layer of insulation for soil. Tankersley’s choice in his own yard? Oak leaf mulch. Why? “The leaves decay slowly, so they release nutrients into the soil over time.” Other options: chopped up plant material from your yard (non-diseased, please), or scattered straw. 

2. Add native plants in spring. Natives are already naturally adapted to outside-of-the-bell-curve extremes, with some sporting roots 15 to 20 feet deep. Compare that to a typical landscape plant with roots just 6 inches deep.


©2013 Chicago Botanic Garden and my.chicagobotanic.org

“I wonder…”  It’s a phrase we hear a lot at the holidays, especially about the outdoor light show that accompanies Wonderland Express, and it inspired us to gather the answers to your FAQs.

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I wonder how many lights there are.  750,000, give or take a string.

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I wonder what kind of lights they use.  LEDs, for the same reasons you have them at home: they last longer and use just 10 percent of the energy of incandescents.

I wonder how long it takes to put up all the lights.  Crews start stringing outdoor lights in October, using ladders or hydraulic truck lifts to reach the tops of the trees.

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I wonder how many lights are on that big tree.  About 300 strings of LEDs light up the approximately 40-foot tree on the Esplanade.

I wonder if they re-use the lights every year.  Most lights are installed and removed by hand every year, tested, wrapped, and stored to re-use the next year. Some lights (entrance road, outer wall) are left on trees for two to three years. As you can imagine, damage from wind and weather and the occasional we-just-couldn’t-reach-it issue cause us to lose some lights every year. For an in-depth look at light installation and removal—and to see a tree delivered by helicopter—check out this video.

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I wonder if the lights are up for Thanksgiving.  Yes! The lights get turned on next Tuesday, November 20, in plenty of time for you to bring family and friends for a pre- or post-Thanksgiving dinner stroll around the grounds.

Bring your sense of wonder.


©2012 Chicago Botanic Garden and my.chicagobotanic.org

Enchanted Kale Forest

Kathy J. —  October 4, 2012 — 1 Comment

PHOTO: a variety of kale plants are growing in the raised beds of the Children's Growing Garden.

We’re all adjusting to the recent drop in temperature, but some plants actually thrive in cooler weather. Check out the redbor kale in the Grunsfeld Children’s Growing Garden. Forget bonsai, these kale varieties look like a miniature forest. Notice the branching leaf shapes are very similar to the trees in the background.

If you look at the kale from just the right angle, it appears to be part of woods that surround the garden.

PHOTO: The branching pattern of the kale leaves resemble miniature trees.See what I mean?

Kale is a member of a plant group called Brassica, which also includes broccoli, cauliflower, cabbage, and mustard. These plants grow well in the cooler months, and so they make excellent spring and fall crops. Since they come in a rich range of colors (dark greens to dusty teals to deep purples), and have an attractive variety of leaves (from smooth to lacy to ruffled), they are a favorite for fall garden displays.

Come to the Garden this month and take your picture near our enchanted kale forest!

Visit chicagobotanic.org/learningcampus/growinggarden for more information on the Grunsfeld Children’s Growing Garden.