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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

Finding the Perfect Match

Undercover Science

Julianne Beck —  February 6, 2013 — 1 Comment
PHOTO: Norm Wickett looks at moss.

Dr. Wickett looks for liverworts growing under the cover of other vegetation on a previous research trip to Costa Rica.

In the deep green landscape of Vancouver, British Columbia, Norm Wickett stood spellbound.  As an undergraduate biology major at the University of British Columbia, he was enchanted by the seemingly endless ribbons of moss wrapped around the region’s natural areas.

“My heart is in mosses,” he shared during our recent conversation in his office at the Chicago Botanic Garden. “My first love in biology is mosses.”

Many of us non-scientists might consider this common plant—often seen lurking in shadowed, damp areas, to be a turnoff. But to Wickett, Ph.D., now a conservation scientist at the Garden, it presents an irresistible puzzle. How did this plant, likely one of the first to have lived on land, evolve from relatively few species during the Jurassic period to the 15,000 species living today? How did it adapt to all of the environmental changes that occurred?

“I’m attracted to more primitive plants,” said Wickett. He enjoys observing early species in the Garden’s Dwarf Conifer Garden.

As the recipient of a new grant from the National Science Foundation, Dr. Wickett is working to put the pieces together. “This grant is going to allow me to get back into mosses and it’s a great opportunity,” he said.

Part of the National Science Foundation initiative called “Assembling the Tree of Life,” Wickett’s project is one of many branches of study the organization is funding to explore how all life is related.

His work, he believes, will answer important questions about the evolution of all plants from mosses to the conifers and flowering foliage that ensued. Also, it will allow him to identify the ways in which past environmental events, such as climate change, influenced the evolution of mosses, other plants, and animals. This type of knowledge will help researchers predict how plants could respond to future environmental changes.

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The spore-bearing capsules of a species of Dicranum moss drew Wickett’s attention while he climbed to a high elevation in Costa Rica.

Wickett’s research process begins in growth chambers in the Garden’s Daniel F. and Ada L. Rice Plant Conservation Science Center. There, he nurtures plants for study. He then takes samples of them to capture the many strands of RNA, or genes, in each species. An expert in plant genetics, he uses new computerized technology to compare the genes of many species of moss and look for patterns.

Why are genetic patterns important? They draw a mazelike course scientists can follow to answer vital questions. Wickett will trace them from species to species in order to see which mosses share RNA and are therefore related. He will also use this information to determine when new species, which share some genes with earlier moss species but also carry some slightly different genes, emerged and what the environmental conditions were at the time that allowed them to thrive.

Timing is everything. He explained that the arrival of new genes must happen at the same time as a complimentary environmental condition for a new species to endure. For example, a plant which developed the ability to hold more water would have been successful during a drought, while it may not have survived during a flood.

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Wickett noticed this patch of Sphagnum moss in Costa Rica at a high elevation.

The genetic change can only last, according to Wickett, if it occurs at a time when it gives the plant a benefit in its environment. “It’s a combination of genetic changes in the moss and changes in the climate and finding the change that is most successful,” said Wickett. “For all these things the first step is that there has to be a change in the genes.” Then, he said, “we can go back in time using computer modeling to see what caused the changes.”  These are the pieces Wickett plans to assemble into a bigger picture of evolution during the next three years of his research project.

It is too early to predict where his discoveries may take him, but for now, at least, it is clear that his heart is in the right place.

 

Look for liverworts, a relative of moss, growing in the Greenhouses on your next visit!


©2013 Chicago Botanic Garden and my.chicagobotanic.org

We recently toured the Greenhouses with Boyce Tankersley, director of living plant documentation, to see what’s in bloom and take in the different climates visitors can enjoy.

In the Arid Greenhouse, we saw a number of species of aloe from South Africa just coming into bloom as well as cacti and succulents.

In the Tropical Greenhouse, we were surrounded by palms and cycads while we admired the many orchids in bloom. Tankersley pointed out the acanthus cultivar (Aphelandra sinclairiana ‘Panama Queen’) native to Panama and Costa Rica, as one of his favorites. 

PHOTO: Panama Queen acanthus (Aphelandra sinclairiana 'Panama Queen')

The Semitropical Greenhouse was filled with blooms like pinkball dombeya (Dombeya wallichii). Native to East Africa and Madagascar, the genus is a highly sought-after ornamental in USDA Zones 9 and warmer.

PHOTO: Pinkball dombeya (Dombeya wallichii)

One of the rarest plants in our collections is Deppea splendens. Native to the mountains of western Mexico, this plant is extinct in the wild.

PHOTO: Deppea splendens

Visit our What’s in Bloom highlight page each week — twice a week during the summer bloom season — to learn more about the different plants in bloom. Then, come out to see them in person for their fragrance and the humidity of the warmer greenhouse climates.


©2013 Chicago Botanic Garden and my.chicagobotanic.org

Signs of Emerald Ash Borer

Tom Tiddens —  January 4, 2013 — 4 Comments

It’s sad but true:

As I drive around the north suburbs, I am noticing many roadside trees with a spray-painted mark or a ribbon around the trunk. As an arborist, I know that these are ash trees marked for removal because of the emerald ash borer (EAB). The emerald ash borer is beginning to hit our area hard, and many municipalities are trying to stay one step ahead of this ash-tree-killing insect by proactively removing these doomed ashes.  

woodpecker_damage_3If you have an ash tree on your property you should be monitoring for this pest, as it is only a matter of time before the borer finds your tree. In winter, the easiest way to identify if your tree already has EAB is to look for woodpecker damage. From a distance, woodpecker damage looks like lighter colored patches on the trunk, as you can see in this picture.  Woodpeckers make these marks as they feed on the tasty (to them) borers that are just under the bark. Once you start seeing evidence of EAB activity, your tree will most likely suffer severe dieback within three years. There is an insecticide treatment that can save your tree, but treatments need to begin before your tree is infested.  

For more information on EAB and treatments, please contact the Garden’s Plant Information Service or check out these sources:


©2013 Chicago Botanic Garden and my.chicagobotanic.org

Squirrel Drey Query

Kathy J. —  December 6, 2012 — 4 Comments

Most people recognize a squirrel nest, called a drey, when they see one. The eastern gray squirrels in our region build dreys in trees for shelter and protection from the elements. What you see as a messy clump of leaves is actually a structure formed from sticks and then lined with leaves and other materials to make it a dry and cozy home.

This month I was walking around my neighborhood in Chicago, and I noticed that three out of four squirrel dreys on my street were located on branches that reach over the street. I had to ask myself why squirrels would build their homes in such a dangerous place.  If the squirrel or its babies fell out, they would not only land on hard concrete but also risk being hit by a car!  Are my neighborhood squirrels somehow related to the Three Little Pigs?

Since I know that is not the case, I started to speculate:

Perhaps squirrels are attracted to that particular view. Maybe thermal currents rising from the asphalt make that spot warmer than a branch over a lawn. Could it be that this spot also puts their predators at risk and therefore is actually a safer place to live? I don’t know!

So, I started looking around to see if there was a pattern in locations of squirrel dreys. To date, my findings are inconclusive. While searching for squirrel dreys, I did notice two other interesting things I would like to share.

PHOTO: This close up of a squirrel drey has an arrow pointing to the green plastic sticking out of the bottom of the drey.

Look carefully to see the bit of green plasting in this photo of a drey.

First, there are fewer squirrel dreys on the Learning Campus than there are in my neighborhood. I suspect that is because the Garden is home to our friend the red-tailed hawk (from a previous blog post) and other predators that are more scarce around my home.

Second, I found a squirrel drey at the Garden that was built with something unusual. If you look carefully in the picture, you will see a green material, possibly shredded plastic like Easter basket grass, sticking out of the bottom. Now, I wonder where it found that! This drey is located on the Garden’s entrance road, near the entrance to the Barbara Carr Administrative Center, before you reach the Gatehouse. You will only notice it if you are looking at squirrel dreys as carefully as I am.

PHOTO: The same drey seen from another angle shows the green plastic.

The green plastic is circled in this view of the squirrel drey.

Take a look at the squirrel dreys around your home, nearby parks, and at the Garden. Are the the squirrels building over the road in your area? Have you seen a squirrel enter or leave a drey? What is the strangest material they have used to build it? If you notice any patterns, post a comment in this blog.


©2012 Chicago Botanic Garden and my.chicagobotanic.org