Pruning The Boxwood

boxwood hedgesThe day that Melissa and her crew comes to prune my boxwood is my favorite day of the gardening year. First and foremost, their pruning is extraordinarily true and square. So precise. It takes a while to set up all of the level lines that will serve at a cutting guide. But beyond the string lines is a skill that is astonishing to watch. The coordination between the eye, and a heavy pair of shears held either horizontally or vertically takes strength, patience, experience, and talent. Loads of talent. I so admire their skill, concentration and resolve. Pruning my boxwood takes the better part of a day.

Secondly, that pruning is a natural extension of the intent of the design. The pleasure I derive from my primarily evergreen landscape is a simple one. I like what weather does to the landscape. Weather acting on the landscape changes the look and experience of it, day after day. The sunny days create shadows that highlight the forms. Overcast days emphasize the contrast of the leaf texture with the volume and mass of the shapes. The random leaves falling from the trees in October provide as much fresh interest as a dusting of new snow. Rain makes all of the evergreen surfaces sparkle.

The boxwood is the most formal element of the landscape, as both the placement and pruning is formal. That hand pruning makes all of the forms clear. That snip snip snip goes on all day long. The sound is regular, and musical. The painstakingly trimmed boxwood is a beautiful contrast to the big wild growing hydrangeas. Boxwood left to its own devices has a beautiful and gently shaggy appearance. That look can work well in a variety of circumstances. But I favor a look that is orderly and defined. I find that clean crisp look relaxing. It is the feeling I want, when I am in the garden.

Melissa and her crew take what I have taken great pains to grow, and prune them into distinct shapes. It is amazing how much they grow out in a year’s time. The pruning timing can be tricky.  I do not like to prune before the spring flush is finished. Pruning too early means it will take another round later on to keep them neat. So later in June, in my zone. I also like to prune before the weather gets too hot.  Pruning on a 90 degree day will insure that the tender growth underneath that has been completely shaded will burn in the blazing hot sun. Pruning is a call to grow, so I try not to prune later in the season.  Evergreen plants should begin the shutting down process in August, so when the winter comes, they are completely dormant.

Most of these boxwood are better than 20 years old. Clearly they cheerfully tolerate this type of pruning. Not all evergreens like this.  Yews especially can die out on the interior if they are pruned into densely formal shapes.  They need some air and light to penetrate to the interior.  All of the spreading yews on my property have a natural look to them, for exactly that reason. A healthy plant is a beautiful plant. If I am looking for a hedging yew with a formal shape, I choose a cultivar that grows that way, naturally. Taxus media “Mooni” is a formal grower, and rarely needs much pruning to keep it in shape.

At days end, I still like the composition decades old. And I know that, as Henry Mitchell once wrote, great gardens are the result of the intensive care of the present. The care my landscape gets might easily be more important than the design. Well cared for is always a good look. Mow the grass, pull the weeds, and prune the shrubs.

I drive Milo and I here every day after work. For several years now, I have parked in front, and ushered my dogs up the front steps. Howard needed help going up even a single step. This was the easiest way in for him. I could lift him over the two sets of two steps. He passed away in late May, but Milo and I still enjoy coming home, and walking up to the front door. How this looks after the trim makes me happy to come home.

I do have a secondary entrance to the side garden. Trimmed boxwood hugs the grass ramp up. The design here makes much of the foreground boxwood, the midground hydrangeas, and the far ground container in the side yard. In the background is a glimpse of the Princeton Gold maple trees. This is a good summer look, but it looks good no matter the season. And no matter the weather.

The side yard boxwood is accompanied by an old hedge of thuja nigra, and a stand of Princeton Gold maple trees to the east on the lower level. I like all of the green. From the trees down to the grass. Peaceful, this.

These side yard boxwoods are at least 20 years old. All trimmed up, they do my head, heart and eye a world of good.  The edger strip enclosing the gravel at their base has been in long enough to go wobbly. But the boxwood is as level straight and true as can be.

See what I mean?

Buck, Milo and I come up here every night to talk over the news of the day. This years news? The boxwood has grown out enough to be flush with the raised steel edger strip. It has taken many years to get to this point, but I am loving the look. The big idea? Those simple pleasures in a landscape can mean so much. Simple is good for the three of us. Well maintained makes every garden maker feel better.

As a designer, I take a good bit of time trying to find out what clients want from their landscapes. That is key to providing them a good design. This client has some big boxwood in her future.

 

Cornus Kousa

From the Missouri Botanical Garden website, read the following about the kousa dogwood. “Cornus kousa, commonly called Kousa dogwood, is a small, deciduous flowering tree or multi-stemmed shrub that typically grows 15-30’ tall, with a vase-shaped habit in the early years but eventually maturing to a more rounded form. Bloom occurs in late spring. The showy parts of the Kousa dogwood “flower” (3-5” across) are the four narrowly pointed petal-like white bracts which surround the center cluster of insignificant, yellowish-green, true flowers. Flowers are followed by berry-like fruits (to 1” diameter) which mature to a pinkish red in summer and persist into fall. Fruits are technically edible, but are usually left for the birds. Oval, pointed leaves (to 4” long) are dark green, but usually turns attractive shades of reddish-purple to scarlet in autumn. Mottled, exfoliating, tan and gray bark on mature trees is attractive in winter.

This matter of fact description does not begin to address the beauty of a kousa dogwood in full and glorious bloom. I doubt I have ever written about them in the 10 years I have been publishing my garden design journal. Primarily as I have never ever seen them so spectacular in flower as they are right now. The kousa dogwood is native to Japan, Korea, China, and Taiwan.  They are rated as hardy and thriving in zone 5 to 8, but my experience suggests they can act a little hostile towards our baking summers, and heavy clay based soil. They seem to favor thin compost rich soil on the acid side that drains in a twinkling of an eye. I do find they perform better than American dogwood (cornus florida) in general.

My theory seems to have some support. This has been the rainiest and coolest spring I can ever remember. We have had many more rainy than dry days. It was 48 degrees this morning, and barely 60 degrees this afternoon. The ground is completely drenched. I make an effort to stay out of the garden, even if it means the foot tall weeds are getting closer to 2 feet tall. The grass is squishy. For the Kousas to put on such a rare show of extravagant bloom says there is definitely something in the air that they like.

The actual flowers are small and insignificant.  All of the show comes from the four stiff bright white bracts that surround the flower. In a stellar year, those thousands of bracts overlap one another to produce a solid sheet of white. Even at maturity, a kousa dogwood is small enough to comfortably place in an urban landscape. Sited with some afternoon shade, a routine source of water and great drainage, all a gardener has to do is wait for that one year when all the stars align for a super bloom.

Should you be one of those people who drives the neighborhood to look at holiday lights, a cruise might be in order.  You can spot them for at least a block away. Out of flower, they have handsome foliage, and even more handsome exfoliating bark when they are older-but the star of the once in a blue moon show are the flowers.

In 2009, a hybrid of Cornus Kousa, and the Pacific coast dogwood, Cornus Nutallii, was introduced from the breeding program at Rutgers University. Again, from the Missouri Botanical Garden website:  the dogwood “Venus”  These four trees planted in the tree lawn at my house are young, but they will grow. Even at a 2″ caliper size, I can spot the flowers from several blocks away.

This hybrid is hardier than either parent.  They thrive in full sun, and grow fast when they are happy. The flowers can easily reach 6″ to 7″ in diameter. We have probably planted better than 100 of them since 2011, with only a few losses. They are a little shy to bloom until they have been in the ground for a year or two, but once they start, they are stop you dead in your tracks gorgeous.

They rival the magnolias for the showiest spring flowering tree.  As with Cornus Kousa, Venus flowers in June, avoiding late spring frosts that so often damage the flowers of magnolias.

A pair of small trees I planted 3 years ago are covered with flowers this year.
This shade garden planted some 4 years ago for my clients features a pair of Venus dogwoods. They are especially happy to have them this year.

A Blast From The Past

Anyone familiar with my garden knows I am a fan of evergreen plants. That makes sense. I live in a gardening zone notorious for its lengthy off season. Not only are our winters long, but our early spring and late fall can also be cold and anything but green. So I grow yews, and arborvitae, and of course, boxwood. A landscape that has something to say all year round is a good landscape. I would say the signs of spring probably presented themselves seriously a week ago or so.  The maples in the tree lawn are dusted with their chartreuse blooms. The grass began greening up. The hydrangeas in the foreground of the picture about are just beginning to leaf out. My large concrete pots are more visually important now than they will be at any other time during the season. They are beautiful, just so. unplanted. But the front yard landscape at this moment is really all about the boxwood. It is green and robust in much the same way it has been all winter.

The boxwood is quick to shed its winter coloration, as are the arborvitae, yews, and the old spruce in the background of the above picture.  I never tire of any of the evergreens, as the weather from one event to the next changes their appearance. The surfaces of the evergreens shimmering with rain drops in the spring is as beautiful as those same surfaces hatted by leaves in the fall, and snow in the winter. They are a crucial part of my landscape.

The role they play is never easier to see than it is now.  I can walk between the pruned and leafless hydrangeas, and see what a prominent role they play in the landscape. And I can even more appreciate the longevity of that service. Most of my boxwood at least 15 years old.

But cultivating evergreens in very cold climates comes with a price. The street side of my boxwood paints a different picture.  Extremely cold and windy winters can damage them. It is important to water evergreens well before winter. Once the ground freezes, the roots will have no opportunity to absorb water again until spring. Needled evergreens present very little surface area to the elements. That structure helps them to naturally conserve moisture over the winter. Though boxwood leaves are small, they are much more broad and thin compared to evergreen needles.  Extremely cold and windy weather can can quickly desiccate the leaves. If you have ever had a cut boxwood wreath on your front door for the holidays, you are aware of how incredibly long cut boxwood branches stay green. The same is true for cut evergreen boughs, or Christmas trees. This damage I am seeing now occurred months ago. The return of the warmer weather is revealing the result of terribly cold weather we had the end of January.

The polar vortex which occurred in January of 2019 is again part of the conversation. The intense cold that gripped a significant portion of the northern midsection of the US set records for cold and wind chills in a number places. I do know what I was doing then. I stayed at home, and only let the dogs out for a few minutes at a time. It was the coldest recorded winter temperature event for Chicago in 25 years.

From Wikipedia   “In late January 2019, a severe cold wave caused by a weakened jet stream around the Arctic polar vortex[3] hit the Midwestern United States and Eastern Canada, killing at least 22 people.[1][2] It came after a winter storm brought up to 13 inches (33 cm) of snow in some regions from January 27–29, and brought the coldest temperatures in over 20 years to most locations in the affected region, including some all-time record lows.[1][4] In early February, the polar vortex moved west,[5] and became locked over Western Canada and the Western United States.[6] As a result, February 2019 was among the coldest and snowiest on record in these regions. In early March, the cold once again shifted east, breaking records in many areas.[7] In mid-March, the cold wave finally retreated, but combined with above-average temperatures, precipitation, and a deep snowpack, widespread flooding ensued in the Central US.” Yes, it was a vicious weather event.

The impact of that extremely cold weather is beginning to be seen. I was faint with surprise when I saw the entire top of this picea mucrunata was dead. If you look up the phrase  “top of my spruce is dead”, most articles cite winter winds and extreme cold first. I see no eveidence of disease or insect damage. Could the polar vortex be to blame?

Of course the time to think about safeguarding evergreens from winter damage is in the fall. I have never seen damage on the boxwood cultivar “Winter Gem”. I plant it extensively now. I rarely plant “Green Velvet” anymore, which is the cultivar I have at home. Thankfully it rarely gets any damage, as I live in a neighborhood where the wind is broken by multiple buildings that surround my landscape, and the sun is tempered by large trees. I have never seen winter damage on boxwood that has been sprayed to the dripping point with VaporGard in the fall. A dry day when the daytime temperature is above 50 produces optimum coverage. Later in the fall, a windbreak of burlap can help. I would have never thought to protect my spruce, but maybe I should. A last bit about the boxwood.  Given the extreme cold we have had in the past years, the price of boxwood has skyrocketed. Replacing my damaged boxwood will be very expensive. Hopefully I will remember this day come the fall.

On a positive note, the below freezing temperatures and snow forecast for this past weekend never materialized. I am pleased to report my magnolia stellata is still in full bloom.

Survival

Several weeks ago my neighborhood in Michigan featured a weather extravaganza of substantially below zero temperatures with wind chills approaching -30 degrees, followed promptly by several days in the fifties. Astonishing, this. Nature is as extraordinary as it is unpredictable. Though I have observed and taken note of natural phenomena over a lifetime of seasons, I regularly experience nature up to something I have never seen before. How I love this. What I have never seen before in the landscape and garden not only keeps me interested, it teaches me. I like adding this and that to my body of experience. Yes, I will always and forever be a student of nature. There really isn’t any other choice, is there?

Those interminable few days I felt imprisoned by extreme cold were followed by days warm enough to be outdoors with or without a jacket. I cannot ever remember a time when 50 degrees felt more delightfully warm and invigorating! How I enjoyed that brief episode of tolerable winter weather. That warm moment had a frigid one hot on its heels.The early morning just days ago was notable for the 1/4″-1/2″ of ice coating every surface, much of which still remains tonight. Yesterday and today?  Rain, freezing rain, sleet, snow, and wind on a loop that kept repeating. A whole winter’s worth of nasty weather, one version after another, hour after hour.

The bitterly cold weather was not a hardship for me. The National Weather Service had advised in advance we had a polar vortex set to dip down into our zone. I took heed of that prediction. My house, constructed and outfitted specifically almost a century ago to provide shelter did what it was designed to do. I had a warm space, with hot and cold running water and electricity. I was lucky in that regard. So many people lost power. I did fully gear up to take the dogs outside, but our exposure to a hostile environment was as limited as I could make it. Out and in, we were, as fast as having old dogs would permit.  A limited exposure to terrifying cold temperatures meant we survived without incident. Terrifying cold? Not the usual thing, but not that unusual either.

The details? A down 3/4 length coat that zips up above the neck. A hood on that coat with a velcro closure. A fuzzy warm headband. Flannel lined jeans. Merino wool socks. Shearling lined winter boots. A wool scarf wrapped around my shoulders and face. And wool gloves underneath wool mittens. Did I forget anything? All of this for an exposure to seriously below zero temperatures for less than five minutes. I do indeed have lots of information and gear to comfort and protect me in bitter cold conditions.  But what about the landscape outside my door?

Winter hardiness in plants is a big, wide, and fiercely debated topic. Annual plants are tropical in origin, and perish once the temperature goes below freezing. Perennial plants routinely die back to the ground. The life in their roots is protected by a mass of soil around them. They winter over in a dormant state. Lavender is a sub shrub. Those stems above ground are alive the entire winter. It is no surprise that sub shrubs in my zone can succumb to brutal winter weather. Anything living above ground in my zone is subject to punishing winter weather. The short story is as follows: Deciduous trees in my zone jettison their leaves in the fall, and shut down for the winter. They hibernate. Likewise woody shrubs. The roots below ground remain viable, but the production of chlorophyll goes on hiatus. The fierce winter weather and winds rarely bother the bare twigs of trees and shrubs. Those twigs are shut down, and buttoned up. Once spring is truly upon us, the buds set in late summer will begin to swell. Perennials in my zone die back to ground level, and wait for a call to grow in the spring. Evergreens? The broad leaved evergreens suffer in brutal winter weather more than any other plant. The picture above, taken in the spring of 2014, after the most brutal winter I have ever experienced, was all about digging up some dead boxwood that had been growing for better than twenty years in front of the shop.

I had no advance warning that we would be subjected to below and just above zero temperatures for lengthy periods. Every brutally cold day that went by was accompanied by an escalating worry. Evergreens of all types were damaged and killed outright in this once in a lifetime fierce winter. The gravelled spaces in the foreground of these pots planted with boxwood this picture show no trace of the plants that died from extreme cold and wind. A friend in the landscape maintenance business persuaded me to stand pat with all of the other damaged plants in this hedge. I am glad I took her advice. Five years after the fact, the south side of this boxwood hedge is all green. These damaged plants did indeed survive.

It takes a lot of exposure to gardening and observing that outcome before it becomes clear that every plant’s first and foremost goal in life is to survive. Species annual plants that most surely will die with the first hard frost will produce seeds. Perennials die back to the ground and go dormant-in an effort to survive the winter. Deciduous trees and shrubs quit producing chlorophyll, and shed their leaves prior to winter. Most woody plants start slowing down in August, in anticipation of the dormant season.  Needled evergreens under stress will set cones profusely. It astonishes me that an evergreen in decline will put huge energy to providing seed for the next generation. Survival can be all about the next generation. As for the here and now, those needles have evolved to present as little surface area as possible that might be damaged by desiccating winds and cold.

I may fear for the plants in my landscape in a bad winter, but they have evolved such to handle adverse conditions. Very few of them need me to intervene on their behalf. In conditions that are so bad as to threaten their life, there are things gardeners can do to provide their treasured plants with a leg up. Good drainage is a major component of winter hardiness. Even Japanese iris want a well drained winter situation. Burlap can help protect boxwood from desiccating winter wind and sun. VaporGard can provide a similar layer of protection.

But by and large, plants have very complex and astonishing mechanisms built in via evolution which are geared to protect their chances of survival. My contribution to that effort is minimal. This is a long way of saying that nature looks after its own. The best contribution I can make to my evergreens is to water them liberally before the ground freezes. An evergreen needle or leaf which is loaded with water prior to the frozen ground is a leaf that is better able to survive.

This section of my 25 year old boxwood hedge shows the sure signs of superficial winter wind and cold damage. This trouble can be trimmed off in the spring. What interests me more is that the substantial dead sections from the 2013 winter have healed.

The evergreens in this pot outside my office door are showing signs of damage from our extreme cold. How could they not? These are cut branches. They have no connection to a parent plant. There are so many ideas that can occupy  a garderner’s winter. My evolution as a gardener-on going.