Red Oak Topiary-to-Be

Topiary is the training of any plant into a shape it couldn't achieve on its own. "Training" mostly means pruning, so topiary also makes plants compact, not just shapely. Topiary from shade trees, then, is an ultimate victory, maintaining a creature that might otherwise become eighty feet high and wide at a fraction of that. 


Beech trees are the usual choice for shade-tree topiary. I'm on it: see my hedge of American beech here, and my Belgian fence of fancy European beeches here. But what about oaks?


Here's a very young red oak—really, just a toddler—at the fall peak of its namesake coloring.


Quercus rubra mis en scene 110717 640


This Quercus rubra is so young and small that it's dwarfed even by the mid-size perennial in front of it. (And what luck that the perennial's spikes of seed heads contrast with the oak foliage like sparklers. Thank you, Elsholtzia stauntonii 'Alba'.) lf the oak were full size, it would be larger than my house. As topiary, it will never become larger than me. 


Why bother training what would otherwise be a huge tree as a fraction-of-that-size shrub? One answer is the perennial's seed spikes: a free-range oak is a a broad canopied shade tree whose lowest branches might still be twenty feet above the ground. Unless the scale of the oak is controlled, I'd never be able to juxtapose its fall foliage with the seed spikes of the Elsholtzia.


Quercus rubra mis en scene tighter 110717 640


In fall, the leaves of red oak are also worth close-at-hand viewing all on their own. What fiery margins of bright red border the burgundy interiors! Without a giant ladder, they'd be impossible to see on branches twenty to sixty feet high.


Quercus rubra fingers foliage 110717 cropped 640


But long after its fall color has passed into a shade of tan aptly named pigskin, the foliage of a topiary oak will retain interest. Like that of much of a free-range oak, it will stick around instead of falling to the ground—and it remains on the branches for most of the winter. As I've explored in connection with oak relatives such as beeches and hornbeams, this peculiar talent (known as marcescense) is best displayed by leaves that aren't too far above ground, nor too far out on a branch whether or not its also a low one.


Training any marcescent plant as topiary, then, is also the way to concentrate the display of its winter foliage to perfection: maintenance of the relatively compact form of a topiary automatically means pruning off growth that is so high or wide that it's outside the close-to-the-trunk zone in which marcescence occurs. Oak topiary is particularly appealing in that oaks manage to marcesce on branches that are unusually high above ground—way too high for their foliage to be appreciated close at hand.


This toddler Quercus rubra is one of a pair I've planted just this past spring. As you can see from the full-length shot below, it's overstatement even to call it a sapling. Nonetheless, 2018 is its year to begin training.


Quercus rubra from the side 110717 640


First, I'll provide a permanent stake, and gently tie the toddler's trunk to it. I'll let the top tip lengthen, because I'm thinking that topiary of about six feet tall would harmonize spatially with the pencil-thin Graham Blandy boxwood immediately behind. Over many years, that narrow column could become fifteen to twenty feet high; a bulky and big-leaved, Louis-sized topiary in front of it would always be in scale.


How eagerly will this species of oak respond to pruning? Will new side branches emerge eagerly, or will they be sparse as well as slow? Dunno: as far as I can determine, topiary of marcescent oaks is terra incognita even in world-class gardening. Maybe I'll be able to give my pair of red oak topiaries only an informal shape. Or perhaps a round-headed dwarf tree—an oak standard, in other words—would be possible.


In years to come, we'll both see the progress as well as the outcome.



Here's more about red oak, plus views of a marvelous old specimen I chanced upon in Canada. 


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