It’s March again, so it must be time for my annual haircut—er, for the shrubs and trees in The Garden, that is.  Woody plants are drawing near to the end of winter dormancy, and that means we’ve entered the year’s first pruning season.

But is pruning easier said than done?  Based on copious scene-of-the-crime evidence suffered by the hacked shrubs and whacked trees I see in our forest city, the answer must be “apparently so!”  True, true, but still a snob’s response.   Any of us can effectively prune well.  If we take the time to learn a few horticultural concepts, basic pruning becomes a pleasant exercise and beneficial service to our shrubs and trees, and easy enough to make a good job of it on the first try.

Certainly pruning has some subtleties, and every plant wants a unique, custom haircut. So, I simplify.  Every time I prune, I consider my four prescriptions: seasonal timing; specific plant habit; desired product; proper cutting technique.  These four prescriptions ensure that I think about all aspects of the job, and give the plant in front of me “its” cut.  Let’s go through the four prescriptions one-by-one.

One: seasonal timing.   A deciduous woody plant remains alive during the winter by slowing its metabolism to a near stop.  But in a few weeks, warmth and lengthening daylight will end dormancy and trigger fresh growth.   And this moment just before the end of dormancy is when we prune.  Why?  Wounds are open to disease and insects for only a short while before active growth begins healing them.  The plant has the entire growing season to respond to its haircut, set new wood, and look natural again by summer’s end.

Two: specific plant habit.  This prescription can usefully modify seasonal timing.  Some plants (maples, magnolias, birches) are “bleeders,” and will leak sap from pruning cuts for a couple of months in the spring.  This plant habit is the foundation of the maple syrup trade.  Bleeding reportedly does the plant no harm, but it doesn’t help (!), and it is also unsightly.  Instead, opt to prune these plants in late June.   They won’t bleed, and will still have enough of the growing season left to heal their wounds.

Other woody plants, especially our flowering shrubs, have the habit of blooming on “old” wood.  That’s wood that was grown as twigs the summer before.  If we prune these plants in late winter, we cut off all the year’s flower buds.  So, its best practice to prune old wood flowering shrubs just after spring’s bloom fades.  Then, they’ll grow new twigs, set abundant flower buds, and blossom vibrantly next spring.  A great example of this are the evergreen azaleas, which  can be sheared after blooming to within an inch of their lives, and flower like crazy again next spring.

Three: desired product. Why do we prune?  Are we growing a fruit tree or a topiary shrub?  Do we want a formal row of shrubbery, or do we just want to keep the lilacs off of the house?  So, we think about what we want the plant to be, but also think about what the plant will accept from us.  This prescription makes sure our pruning intentions don’t contradict seasonal timing and plant habit.  And taken together, the first three prescriptions build a f foundation for pruning with purpose rather than reckless abandon (as fun as that can be). 

Four: proper cutting technique.  This prescription is important because it recognizes how woody branches heal wounds, and guides us to make cuts that encourage quick recovery.  In brief,

• When removing a side branch, never remove any bark or wood that is part of the main branch or trunk
• Always cut at an angle that is “backwards-in-the-mirror” from the warty branch collar scar growing at the branch base
• And when cutting a twig, try to cut just above a side bud, and at the same slant as the bud
• Finally, use sharp tools, and make cuts that are clean, not ragged

These mechanics are also clearly depicted in the accompanying photos, and the technique can be kept as simple as that. 

I recommend a good pruning book to accompany the four prescriptions.  Find a book with numerous pictures, and a big species-by-species how-to list for the particular habits of our various woody plants.

Of course rules are made to be broken, and evergreens sometimes follow some slightly different protocols. More about pruning in the future, for sure. Otherwise, I think we’re ready to soak up some March sun, and give our yard its annual haircut.

And my own haircut?  Er, I can put that off until April, at least. 

P.S.: If you are interested in the biology behind proper cutting technique, find a book by Alex Shigo (he’s got a few, and they’re mostly interchangeable), or ask me, and I’ll blog about it.

Posted by Mark Bir

It is snowing again and winter drags on.  Yes, the days are growing longer, but –   Yes, the calendar promises spring soon, but—   —I am staring into the flat, gray panel of this day and see only dreary doubt.  More than warmth, more than sun rays, I am wanting for color.

Leafless and bright in contrast to grim sky, the Woodland Garden sycamore tree is wearing a Josephs’ coat for winter.  Its patchy bark is broken into individual flakes in satiny shades of olive, milky chartreuse, cinnamon, and pale ochre.  But the Garden specimen lacks the chalky white patches usual to our local sycamore (Platanus occidentalis) which suggests to me that it might be a plane tree, itself a hybrid of local sycamore and Asian sycamore (Platanus orientalis).  I will know more when it leafs out, and remember to post the answer here.

Extant since at least the 1800s, the plane tree is a salt- and soil-tolerant plant that thrives on the grit of city living, and proves it with a century of success beautifying the streets of Paris, London, and New York.  It is one of those trees that is ubiquitous in the image and experience of city life, and has been woven into the background cloth of our urban consciousness.  Severe and continual pruning is tolerated to the extent that the plane tree is widely trained into street-side topiary: witness the row of them flanking The Terrace; witness the double row reflecting in the Art Museum lagoon.

The native sycamore is a denizen of Ohio’s river bottoms, where life favors those who can outgrow the dangers of flood and ice.  Often clinging to collapsing mud banks, sycamores rocket up to the sliver of sky above the water, attain great height early, and save commensurate girth for later in life.   They are prolific seeders, and employ wind and water to spread their future.  Older survivors thicken and roughen and boast gashes like trophies in their trunks from annual warfare with river ice and the spring thaw.  And, if we don’t have one living on our ten acres, there are a few chalky-white native sycamores growing along M.L.K. Boulevard.

More color at the far end of the C.K. Patrick Walk.   An Asian spicebush (Lindera orientalis) there hangs bright, strappy leaves like feathers made of hammered copper.   The spicebush is dormant and deciduous, yet its leaves persist.  The leaves are dead but for the twig-end of their stems.  Their separation (due to abscission, a hormone-regulated, compartmentalized cell death and subsequent tissue separation) was halted last autumn and will be completed this spring, and there’s a 25-cent word for it: marcescence.  It is also common with many of our oaks (see them around Gateway) and young beech trees. If marcescence is considered a juvenile trait, I’ve met many mature oaks that would argue about that. With Asian spicebush it is complete and quite formal, for no leaves will drop until buds begin to swell.

More color.  Nearby, tucked in the Rose Garden border, grows a mass of evergreen azaleas.  The slender, hairy-like-a-fly leaves vary in color from earthy green to rust.  This variety, ‘Cascade,’  is necessarily a hybrid of Japanese azaleas, since all of North America’s are deciduous.  It has white flowers in spring, and golden leaves in autumn.  Curiously to me, white blooming evergreen azaleas have golden autumn foliage, and red-blooming have ruddy or bloody autumn foliage.  Evergreen azaleas are actually partially deciduous, and will lose less or more of their leaves from year to year, depending on each winter’s severity.

More color.   Still in the Rose Garden, the glossy evergreen leaves on a holly bush attract my attention.   In this light, they absolutely glow.   Holly is a tribe of (mostly) evergreen plants that inhabit North America, Europe and parts of Asia.   This one is an inkberry (Ilex glabra), and aptly bears black berries each autumn.  Like all hollies, plants are male or female, and both are needed to set fruit.  This Eastern U.S. native makes an interesting garden alternative in those places where you might usually plant a bay.   Prettiest in winter, inkberry is slow growing, soil tolerant and generally well-behaved.

The plant world exhibits a continuum of leaf habit from fully evergreen to fully deciduous.  Each variation is a particular tactic to a shared problem; water availability.    To plants it makes little matter if it is Cleveland’s winter drought, or Madagascar’s desert drought: to survive, they must lose leaves or waterproof leaves, or a little of both.

And to my delight, in battleship gray Cleveland, they do so in color.

Posted by Mark Bir
 
 

 …when we neglect to prune our trees.

Some trees need very little help to grow tall, straight and well-balanced. Others benefit from a little shaping. This weeping redbud needs a lot of “untangling” each winter with the help of my recently sharpened pruners.

I enjoy a good gnarly tree. Especially this time of year when the naked branching structure is fully exposed. The sculpted twists and turns don’t necessarily happen by accident. Pruning trees is an art, especially when dealing with the gnarly, twisting and weeping tree varieties.

Late winter is a great time to prune trees. By removing the end growth of a branch, you are forcing the side buds to take over. Redirecting growth is that simple.

It certainly helps to start with a young tree. There is usually enough growth from the previous season that there is no need to bend, wire or force branches to grow in a certain direction. Instead, simply encourage the new growth that you like and remove the rest. With a little vision, you can determine which branches will grow to become the beefy arms of the sculpture. Selectively thin out competing branches and make cuts each year to flex those arms in a manner that you find appealing.

When dealing with a tree that just wants to weep, consider allowing a few new shoots to grow upwards so that you can fold these twigs back over the tree to create a layering effect to the branching. Art is subjective. But the nice thing about this art form is that it is also alive. You can revisit your artwork every winter and change or improve upon it as you see fit.

Posted by Bob Rensel

There is light everywhere.  The sky is blinding-blue infinity. The snow draped across The Garden is as brilliant as  cut glass and gemstones. 

Twigs shimmer and glint like daggers flashing with flames. But it is really cold out this morning, somewhere around 10 F. With each of my steps, the snow squeaks underfoot. The air is dry as sandpaper and scrapes across my lips as I inhale.  Today is a contradiction in fire and ice.

“Crunch, crunch,” say my steps.  I pretend I’m not freezing, because the long dark is over and it’s a great day to prowl The Garden.

Our rhododendrons (Rhododendron cvs.) in The Japanese Garden look especially cold.  The leaves have pointed their tips toward the ground, and tightly curled themselves into green cigars. They’re huddling against the cold, in an effort to minimize evaporative water loss to the desiccated air.  When it warms up, the leaves will un-curl and stand up again.  They accomplish this directionless, or nastic, movement by draining and filling specialized elastic, temperature-sensitive motor cells, which pull the leaves along with them as they change shape.

Contrast nastic movement with tropic plant movements, where plants respond to stimuli by moving toward or away from their particular nudge.  Phototropism (light), gravitropism (gravity), thigmotropism (touch), and geotropism (earth) move leaves, stems and roots the directions they need to go. Their mechanisms are diverse, often complicated, and always fascinating; I’d like to promise more of this in a later blog. So, let’s not even mention animal and wind mediated movements, which make plants world travelers.

The little grove of hemlocks (Tsuga canadensis) just across the brook seems more obviously content with the cold.  Like the rhododendrons they are evergreen plants, but they employ another winter survival strategy.  First, their leaves are very tiny to limit surface area, and thus evaporative loss.  Second, their leaves are coated with a thick, resinous cuticle, which waterproofs just like the paraffin painted on our grocery-store rutabagas lately. Third, hemlock leaves have no pores on their upper surfaces, and only two rows on their undersides, those being nestled up against the mid-veins.

Fifty paces away, in the shade of the Woodland Garden hillside, a non-woody evergreen hides in the snow, the Christmas fern (Polystichum acrostichoides).  I brush away some frost crystals, and there they are, clad in olive drab, waiting for April. They’re common in Ohio woods, and on days like this appear cheery and gay, climbing our ravines in little green armies.

With the frozen earth preventing water uptake, it is impossible for Christmas ferns to photosynthesize today.  So they wait, green and ready.  Plants that keep their leaves through the winter use a couple techniques to prevent living cells from freezing and bursting.  They move intracellular water just outside of their cells walls, where it safely freezes. This simultaneously concentrates the dissolved carbohydrate inside the cell, which then acts as antifreeze.  Green-in-winter plants also employ antifreeze proteins that bind water molecules and prevent them from crystallizing.

I make an about-face, toward the big tulip tree (Liriodendron tulipifera) growing in the Woodland Garden.  Seventy-five feet above me its top branches bend and angle and stay substantial out to their twig-tips.  They are bearing erect seed clusters that glow orange in the light, and look like hundreds of sky candles burning to warm the frozen sun.  The individual seeds are spindled around central pins, and are upright and clasping like folded umbrellas.  The seeds not eaten by fox squirrels will break free one-by-one and flutter away on little wings.  All will be down by spring, leaving just the pins on the branches.

Fighting by not fighting, the tulip threw its leaves to the ground and drained its sap to the roots last autumn.  It stands today, visibly dormant and indifferent to winter…but not quite.  The mitten-shaped buds hold some living cells, quiet but alive, that wait beneath the protection of woody scales.  Come spring, they will burn stored starches pumped from below, grow out of their cocoons, and become summer’s leaves.

Fire and ice in the Gardens.  So beautiful, but I’m goin’ inside now—“crunch, crunch”–man, its cold out here.

Posted by Mark Bir

Mid-winter at Cleveland Botanical Garden is a time to look up.  Vivid autumn is a faded photograph lost in mom’s dresser drawer, and the twinkle of the holidays is now an unplugged string of lights lying in the snow. The days are still weak but growing stronger, and the sky is a drama of frozen smoke and clouds like anvils and granite.

The leaves are gone and the little grove is laid bare. Our dozens of big trees, remnants of Wade Oval’s once-forest of oaks and tulips, now dare to throw their crosshatch of flying beam and lintel against the framing sky.

One tree in particular catches my attention.  It is the red oak (Quercus rubra) growing in the circle of lawn near the C.K. Patrick Garden. There is no better specimen in Northeast Ohio.  From a sturdy buttress of exposed roots, it bends skyward on a massive, branchless trunk.  The bark is steely and segmented like armor plate.  At about 45 feet above the turf, it abruptly sends out three thick limbs, and then a few feet higher, several more. They proceed to radiate upward, divide and sub-divide in patterns repeating the stronger patterns beneath them, and end in pencil-twigs and rocket-buds, 70 feet aloft; a crown that offers royalty to the surrounding grove. 

Red oaks are perhaps the most common deciduous tree in our local upland woods.  But familiarity does not breed contempt.  Their numbers provide endless variation to the red oak theme.  For instance, the bowed trunk that our sample displays is a tendency throughout the species — like a gentle conceit — that is fun to notice.  Sometimes, it is rakish and exaggerated on that odd individual daring to grow out over the brink of a local ravine.  Couple this trait to the elbowed, muscled, sinewy limbs, and the red oak becomes so distinctive that a spotter can identify a red oak against the far horizon. 

Oaks as a group number over 700 species, and circumnavigate the North Temperate Zone. They are then split into the red and white oak tribes. Ours is in the red tribe, which means that its leaves have pointed, minutely-bristled lobes instead of rounded lobes; and that its acorns take two growing seasons to mature on the branch instead of just one.

Red oak acorns look like velvety “heads” sporting jaunty berets. They fall to the ground in October, immediately germinate and issue carmine-red tap roots, pause for the winter, then resume business next spring.  This was a good year for acorns (every several is a cyclical “mast” year), and it was like walking on garden marbles for awhile there. But today, most of ours are reduced to husks heaped at the base of the trunk, complements of hungry fox squirrels. 

Please don’t surrender these days to the television.  Look up through our Garden and witness the beauty and strength of the red oak revealed, as it stands against Cleveland’s dramatic winter sky. Too soon it will be April, and so many leaves attendant.

Posted Mark Bir

When I started working as a professional gardener, people would ask me to identify trees in their yard. Needless to say, I shrugged my shoulders a lot, especially in the winter. Since then, I have learned a bit from my gardening colleagues, from books and from on-line resources. I’ve found that if you know what to look for, you can usually figure it out.

Buds, for instance, have a lot of varying characteristics that will help ID a tree. For starters, how are they arranged on the branch?  If they are opposite each other, that helps narrow it down to a handful of likely candidates here in northern Ohio. Maple, ash, buckeye, dogwood and lilac have opposite bud arrangements on their branches.

Posted by Bob Rensel

I promised last time to highlight this book by Joe Lamp’l, our keynote for our upcoming Sustainability Symposium, and I really enjoyed this read. Its best quality: he boils some complex scientific topics down to easy-to-understand levels.  I found so much in here to share that I’m splitting this entry into 2 parts, so please enjoy.

 Part I:

In the chapter on Reducing Garden Chemicals is a very useful section on “…the unintended effect of de-icers in winter.” Useful, because well, we live in Cleveland and we use lots of de-icers. And we should if we don’t want people or pets slipping and falling. But there are many different products out there that can damage plants and soils in various ways. One product he does recommend as a salt-free de-icer is SafePaw™. Good to know!

I am also intrigued by chapter four: Landscaping to Control Runoff.  In the section, “plant trees and shrubs to control erosion” there is a nice little list of helpful trees and shrubs you can use for this purpose including spicebush, serviceberry and larch.  The thinking is that the tree canopy of these plants slows down the rain velocity, stores water on their leaves for a short period of time, and the roots help uptake water from the soil to prevent excessive runoff. In “plant a rain garden” there is once again a helpful list of plants to use in such a plot.  Joe-pye (one of my faves), swamp milkweed (another fave), and Jack-in-the-pulpit make this list. Stay tuned for chapter 7 highlights next time: Gardening to Protect the Ecosystem!

Posted by Renata Brown

 Part II: Ornamental native plants 

 

The American persimmon (Diospyros virginiana) has a special place in the affections of people who like to harvest wild foods. The one-to-two-inch orange globes ripen late and remain on the trees into early winter, growing sweeter, until they finally soften enough to drop to the ground. Before ripening they are quite astringent, but at this soft stage they have a rich, aromatic flavor and texture all their own.

Native American people harvested the fruits to eat fresh or dry. There were also a number of medicinal uses for fruits and for bark. The word “persimmon” derives from the Algonquin name for this native fruit. European settlers quickly developed a fondness for it, and discovered dozens of new ways to enjoy it. I was fascinated to learn that people have made wine, beer, vinegar, and molasses from persimmons, in addition to the more predictable jams and baked goods. Persimmon pudding is a traditional holiday dessert in regions of the Southeast where persimmons are plentiful. I hope to try making persimmon leather if I manage to harvest any myself!

Persimmons belong to the same family as tropical Ebony trees. In fact, most of its relatives are tropical. The other widely known species of edible persimmon is Japanese (Diospyros kaki), which produces a larger fruit, but is less winter hardy. The American persimmon is hardy in zones 5-9, and can grow to 135 feet high in rich bottomland soil. It is more typically around 30 feet high, and can probably be controlled by pruning. Some plants in the wild may bear only male or only female flowers. Persimmon afficionados have developed a number of cultivars for larger, tastier and more reliable fruits, too.

The persimmon is just one of many beautiful and useful plants in the Western Reserve Herb Society’s Herb Garden. The photo depicts the small, very productive tree planted on the Herb Garden Terrace just outside of the big window of Clark Hall.

      If you live in the Cleveland area, you may have noticed that there are a lot of acorns this year. I’ve certainly been noticing them as they have been falling on my head or crunching under my shoes.  Reports from other places in Ohio are a little more spotty, but we certainly have a good supply here from almost all of our different oak species. What you probably didn’t notice is that last year there were very few acorns to be found in this area.  While you might not give them much notice, acorns can have huge impacts on wildlife and that can affect us or our gardens in turn.

      Squirrels certainly aren’t the only wild animals that eat acorns. More than 90 animal species, including deer, turkeys, mice, and a number of birds and insects also rely on acorns as a vital food source in Ohio. Acorns are highly nutritious, and abundant supplies can increase wildlife populations both in number of animals surviving through the winter and in number of offspring. This, in turn, affects carnivore populations, such as our birds of prey.

    Acorn crops can vary greatly from year to year for a variety of reasons, not all of which are completely understood. Some species of oaks tend to produce large crops in cycles of 2 to 7 years.  It is in the best interest of oaks to produce a ‘bumper’ crop of acorns after a year or two of relatively small crops. Wildlife populations that feed on acorns, especially insects like the acorn weevil, will decrease following years of small crops increasing the odds that acorns produced in a boom year will have a chance to grow.  

     So what does this all mean to us?  Well, a good acorn crop is going to be a good thing for us for now. As long as there are acorns on the ground, the deer are going to stick to the woods and be less likely to be munching in you garden, and the squirrels might just leave your bulbs in the ground.  But populations are also going to increase in the long run. It might be good news for hunters, but if the acorn crops take a sudden drop while populations are high, you can expect to have lots of hungry deer leaving wooded areas, eating your plants, and wandering into traffic.

Posted By Nate Tschaenn