Pruning The Boxwood

June 23b 2013 (1)The day the evergreens get pruned at the shop is one of my favorite days in the gardening year.  Mindy from M and M  Flowers comes with a crew; they make a day of it.  The first order of business is the discussion.  Are we pruning as usual?  Is there perhaps a new shape or different direction in mind?

pruning-boxwood.jpgMaking changes to the shape of a boxwood hedge- even an established hedge- is not difficult or impossible.  It just takes time. The spheres at the corners of the parterres have not grown in evenly all around. The west side spheres get more water, as the land drains in that direction.  The east side spheres are planted in what was once asphalt, and they are shaded by the lindens.

pruned-boxwood.jpgThe spheres to the east also suffered a considerable fungal infection that has been very difficult to cure.  Simply put, the conditions for the 4 spheres are not at all equal.  One pair is much larger and more robust than the other.  So there was discussion about a moving towards a different shape at all 4 corners.

boxwood.jpgThe corner spheres could be trimmed as follows.  The bottom of the shrub could be brought into line with the existing rectangular hedge.  The top of the shrub could be pruned as a top-knot, or a smaller sphere that would appear to sit on top of the hedge.  This pruning would take a few years to accomplish, as it means pruning down to old wood.  There would be bare spots that would need to grow in.

green-velvet-boxwoodWe have some time to think this over.  Though I like to wait until the spring growth is fully flushed out before any pruning is done, pruning back to bare wood as the heat of the summer season is imminent is a recipe for burn. Boxwood grows out of winter burn fairly readily, but summer burn is an unsightly state of affairs that persists.

formally-pruned-boxwood.jpgI am not so sure that it bothers me that the spheres do not match.  Perfection is a state that does not really apply to living things.  We may just stay the course. But there is always the option to change course in a landscape.  That just takes planning, and patience.

pruning-evergreen-shrubs.jpgThis hedge has been grown from the species buxus koreana microphylla.  It is a big growing boxwood.  The hedge has been maintained at a height of 32″ and a width of 48″ for a number of years.  Grown in full sun, it readily handles the winter wind and cold weather.  The only danger posed by the winter is when we have heavy snow, the weight of which can crack the woody branches.  Those cracks make the shrub more susceptible to fungal infections.  It’s not always easy to decide whether to remove the snow, or let it be.  Disturbing branches when they are frozen can produce more damage than the snow itself.

pruning-a-boxwood-hedgeKorean boxwood does have a pronounced orangy cast in the winter, a characteristic that is not to everyone’s taste.  Our most important issue is tending a hedge that is in good proportion to the size of the building.  If that large overall size were not so important, “Green Velvet” boxwood maintains its green color all winter, and matures at 3′ by 3′.  “Green Mountain” boxwood is  virtually indistinguishable from Green Velevet, but matures at 4′ tall, and 3′ wide.  “Green Gem” is a good choice, if a more refined leaf and smaller mature size is what your garden needs.


pruning-the-boxwood.jpgWe lost 2 boxwood in the hedge over this past winter.  We did have one replacement available. In this spot, we went another direction.  We stitched the hedge back together, with a pair of potted boxwoods.

pruning-the-boxwood.jpgThe pruning makes a world of difference in the appearance of this garden.  I am enjoying that change thoroughly.  If you have a boxwood hedge or specimen boxwood plants that ask for a precision pruning, I highly recommend M and M Flowers.  Their work is superb.  248  340  0796.


Beloved Boxwood


I can think of few plants that have a better service record than my beloved boxwood.  Properly cared for, they are very long lived.  Old boxwoods have an aura of age which only adds to their beauty.  They demand little, and give much.  Few broadleaved evergreens can tolerate our cold winters.  Though our nurseries are stuffed with blooming Catawbiense hybrid rhododendron in the spring, it is a constant battle to keep them happy and healthy.  They simply like Philadelphia better than Detroit.  Ilex, kalmia and the like suffer here as well.  The boxwood-they thrive.  I plant the very hardy Buxus microphylla hybrid Green Velvet; the winter color is as richly green as the summer.      

This giant untrimmed ball of buxus microphylla koreana has lived in this French terra cotta pot for 5 years.  We wheel it into the garage for the winter-to protect the pot, not the boxwood.  The garage has neither light nor heat-not a problem.  In March we wheel it back outside for another season.  Boxwood can be quite hardy in pots or windowboxes outdoors all winter; the container needs to be frostproof, and the maintenance thoughtful. The buxus microphylla which forms the hedge outside my shop will take on an orangy-olive color in the winter; this winter color is typical.  The front of the shop is a southern exposure.  The hedge has been there 12 years, and has yet to burn over a winter. Most of the hybrids of boxwood hardy in zone 5 come from this species.

Buxus Sempervirens, commonly called European, or Southern box, is the boxwood variety of my dreams.  Lush and large growing, they adapt easily to any sculptural pruning you might dream up. They can grow to twenty feet tall.   If you have seen the boxwood planted by Beatrix Farrand at Dumbarton Oaks in Washington, you know how a boxwood planting can be sculpture.  Pruned into undulating cloud shapes, this planting is a showstopper.  I have seen this boxwood planted in ground in my zone, but a particularly vicious winter has the power to kill them. They are rated for zones 6-8; this rating means what it says. I therefore recommend using them in pots, and wintering them in an interior space. They only need an unheated space; you want them to go dormant, and only wake up when the worst of the winter is past. 

I rarely see boxwood topiary of size grown from a zone 5 hardy boxwood.  Boxwood is a relatively slow grower; it might take 7 years to get a cutting of Buxus Green Velvet” to 24″ tall. Boxwood in general are expensive.  Southern box grows faster in a mild climate, such as the Pacific northwest; they routinely flush growth twice there in a single season. As southern box is a big plant when mature, large scale topiaries such as these are usually grown from this variety.  A topiary this size, with a trunk caliper this large-very pricey.  But priceless in its return.  While it is an investment, your investment will grow and prosper over the years-what gardener could ask for more?   

This boxwood sphere with its attendant topknot/hairdo-what a great looking and very special plant.  You might grow topiary boxwood yourself from cuttings-it just takes years.  Any grower of nursery material-how incredibly patient they are. They can see the potential for a decently sized plant in a cutting.  But very large specimen boxwood such as these do not come along so often; most growers like to sell their material in a shorter time frame.  Now and then we will find a grower who has a love for growing unusually large or largely unusual plant material; these growers interest me. 

Boxwood is as happy in a supporting form as it is being the star of the show.  Their tolerance for clipping and shearing makes them an ideal formal evergreen hedging material, when a small hedge is desirable.  These large circular beds beds planted with tulips have a drama that would not be possible with tulips alone.  Their geometry and symmetry is an organizing metaphor for this particular garden.  The loose growing tulips have an excellent visual partner in the boxwood.

This is not to say boxwood is without its problems. The boxwood at the Chicago Botanic garden suffered terrible damage after last year’s winter-as the sign says. The boxwood in the front of my shop sustained damage much like this. In my case, huge snow loads, as well as freezing and thawing, weighed the plants down such that stems split, and allowed a fungal infection to invade.  Heartbreaking. 

These boxwood in my garden suffered similar damage-but I would not for one moment consider not growing them.  They are beautiful year round.  Gorgeous in growth.  Beautiful in the rain, or with fall leaves dusting their tops.  Beautiful as a topiary or a hedge.  Spectacular in pots.

They are a quietly handsome groundcover, under my Yellow Butterflies magnolias.   The day the petals fall to the boxwood-one of my favorite days of the gardening year.