A Gardening Journal

Today in the Garden of a Lifetime: 'Graham Blandy' Boxwood

This Winter's extreme and sustained cold has bronzed much of the foliage of the southern magnolias espaliered up the west side of the house. The magnolias will recover just fine—and, meanwhile, the unusual mahogany hue of their foliage only enhances the bright green foliage of the columnar box in front.

 

Buxus sempervirens Graham Blandy North of the pair overall 031215 640

 

This strikingly narrow box cultivar is Buxus sempervirens 'Graham Blandy'. It doesn't know the meaning of the word "horizontal." All of its branches grow resolutely upward, from the newest twigs to the oldest and woodiest central stems. In climates with little or no snow, this automatic verticality enables 'Graham Blandy' to be planted closely (a foot apart) and left to grow into a startlingly tall and narrow hedge. Just keep the top even with a once-a-year trim, and let the box do the rest.

 

Buxus sempervirens Graham Blandy foliage detail 031215 640 

 

But 'Graham Blandy' needs your help when growing anywhere it will experience heavy snows, even if they are rare and ephemeral. The shrub's vertical stems are cruelly susceptible to becoming splayed out by accumulating snow, and they usually don't bounce back after the snow melts. To keep them vertical, I wrap the entire shrub with a spiral of twine, just like I do for 'Sky Pencil' holly and 'Gold Cone' juniper.

 

If you do this in the Fall, the twine is on display all Winter. I like that look. But if you twine in Spring or early Summer, which I did for these shrubs of 'Graham Blandy', the very newest growth hides the twine. Look again at the picture above: It's almost impossible to see the twine. Below, a closer look, showing an inch of twine just above and to the right of center.

 

Buxus sempervirens Graham Blandy foliage detail cropped 031215 640

 

'Graham Blandy' will grow too high to remain erect just by dint of this twining. Like the 'Sky Pencil' holly, its old stems never grow thick enough or tall enough to support the shrub's columnar habit; 'Graham Blandy' also needs a backbone that's up to the task. I'll start with a ten-foot length of rebar, which I can pound into the ground discretely, right at the back of each of my pair of these shrubs. They are already nine feet high, so that ten-foot length won't show. 

 

Buxus sempervirens Graham Blandy Magnolia grandiflora Brackens Brown Beauty west facade overall 031215 640

 

As these columnar shrubs grow, I'll pound this starter ten-foot rebar much more deeply into the ground—and then use it as a steadying stake to which I can tie taller and taller lengths of rebar. Next year, I'll tie a twelve-foot length to the pounded-in ten footer. A few years after that, I'll switch it to a sixteen footer.

 

Maybe in a decade—and certainly in two—this pair of 'Graham Blandy' box will have grown as high as the roof, and I'll have needed to switch from sixteen-foot stakes to twenty footers. Handily, the boxwoods' location just a few feet in front of the espaliered magnolias provides a solid anchor point for the ever-higher tops of these backbone stakes. The center of an eight-foot length of wire can be wrapped around the top tip of each, and then each end of the wire can be led diagonally back to the nearest of the rungs of the magnolias' espalier frames. With just this modest side-to-side bracing, the top of the box will sway only minimally even though, over time, the shrubs will lengthen to the roof. Plus, with the shrubs' growth held firmly to the vertical stakes, their centers of gravity are always within inches of the stake. With such a small footprint and a steady tip, the rigidity of the stake will combine with the sort-of-rigidity of the shrubs' erect branches to keep the plants stable as well as upright.

 

Even better, the very act of providing this weather-proof verticality enables the shrubs to grow even taller than they ever would if they were self-supporting. This is only partly because growth will be protected from being broken apart by snow, ice, and high wind. Woody stems don't growth thicker just from sheer age; they are stimulated to grow thicker by the side-to-side motion caused by the wind. The twining and rebar support prevents that motion, while also preventing weather-induced loss of branches. Without the stimulation to thicken, and with maximal preservation of branches and their foliage, the shrub's capability for photosynthesis increases with its height—and, thanks to the secure verticality, isn't at risk of impairment. Plants don't have an on-off switch for photosynthesis: Whenever conditions are acceptable, it happens. Without impetus to put some of that energy into thicker stems, it will be used all the more for further upward growth. These staked-and-steadied 'Graham Blandy' boxes will grow taller than any free-range ones—and more quickly, too. 

 

 

Here's a look at a boxwood cousin with somewhat less pointy leaves: Buxus sempervirens 'Rotundifolia'. Its hardiness and culture is the same, and its broad-and-moundy habit is more typical for the species.

 

Here's a look at how happy 'Bracken's Brown Beauty' looks in Summer. Since this 2012 post, this pair of trees has continued to thrive. The goals now are to keep them lower than the second-story roof, and to complete their training around and over the second-story window at the center of the house's west facade.  

 
 
FacebookTwitterRSS Feed

Stay in touch!

 

Sign up for twice-monthly eNews, plus notification of new posts:

 

* indicates required