A Gardening Journal
Fastigiate Cornelian Cherry in Bloom
- Published: May 05 2015
The flowers of Cornelian cherry are just one of this tree's talents. It makes a great hedge, too. In the previous post, I pondered just how tricky the pruning of such a hedge might be: It's typical that growth trimmed into hedges flowers less prolifically than when free-range.
But my patient editor directed me to her own more mature specimen of Cornus mas 'Golden Glory'—photographed with gratitude here—as proof that I needn't worry. The tree flowers the full length of its branches, not just at the tips that would likely be pruned off during "hedging." Indeed, branches six and eight feet long were in bloom up and up and up.
Because all the branches of 'Golden Glory' are more or less vertical, it's especially easy to appreciate that, indeed, they are in flower from bottom to top—
—or nearly so. The very tips were flowerless, because they were last year's newest growth, and this species' twigs aren't old enough to flower until Spring of their second year. Notice how much shorter these flowerless tips are than on my much younger tree. This specimen is fourteen years old, and its rate of growth has slowed to about six inches a year, not twelve or eighteen.
On such a large plant, bare stem tips fifteen feet in the air are hardly noticeable. What is striking is how the flowering seems to have ceased in the tree's lower portions.
My editor attributes this not to any inherent loss of floriferousness even on the tree's oldest growth, but to her fastidious pruning and thinning so as to better reveal the tree's major branches and oldest bark.
And, indeed, the flowers do obscure even major branches because they aren't borne directly from old growth but, rather, from short laterals. Below is that same shot up the vertical length of a branch that has been growing for several years since the in-focus portion of the branch first flowered. While the branch itself may have shot up—literally—five or eight feet, those flowering laterals have grown barely an inch or two.
These flowering stems' congested "lifestyle" seems the same as that of spurs on, say, wisteria. Non-flowering stems of this woody vine can be almost uncontrollably vigorous, and can lengthen by many yards a season. But the gnarly spurs that bear the flowers seem to increase by only millimeters one year to the next. Cornus mas forms spurs, too—and, as with wisteria, they produce the flowers.
And so, back to the question of forming Cornus mas into a hedge. Thanks to the countless spurs growing deeper within the canopy, a hedge of Cornelian cherry is likely to flower just as well as if the trees were never pruned: You could prune off all the new twigs each year and not affect the spurs at all, because the new twigs are formed at the tips of branches, which, for a hedge, means only the hedge's outer surface. The spurs are safe.
I'm hard pressed to think of another hedge subject whose flowering would seem to be completely unimpeded by pruning. Hollies, say, are sparse producers of berries when grown as a hedge. The branches don't flower until their second season—but, unlike those of Cornus mas, never thereafter. To keep a holly hedge in shape and also heavily in berry, you'd need to prune only every other year. The year of pruning, you'd cut off branches that were old enough to flower and berry, but you'd stimulate growth of new stems that would flower and berry the next year, when you would not prune. Perhaps only ornamental quince can equal Cornelian cherry in flowering well as a hedge. It, too, produces flowers from spurs along the length of its mature stems.
When to prune Cornus mas when forming it into a hedge? The tree is hardy to Zone 4, so if you're gardening in Zone 6 and warmer, you could prune almost anytime and the resultant young twigs would likely be hardy. But if you prune in early Spring, just before the flowers begin emerging from the spurs, you'll have enjoyed these bare stems' subtle red coloring all Winter but also get them out of the way so that the flowers can hog center stage.
Interestingly, the much older tree of Cornus mas that I photographed first was spectacularly full of bloom. It's flourishing in a public park nearby, where there is almost certainly not sufficient maintenance to permit the tree to be throughly tip-pruned. And yet, no first-year twigs—which would not be covered in flowers—are showing. After several more decades of growth than the fourteen-year-old adolescent photographed here, spurs have ramified into multibranched "monsters" perhaps six inches high. Perhaps by the time Cornus mas becomes an éminence grise, its growth has slowed so much that first-year twigs are no longer even produced, in favor of the milimeter-a-year creep of the spurs. An additional possibility is that the lack of the tip growth removes any potential growth inhibition that tips typically exert on stems farther down the branch. And because there are no other branches farther down the stems than flowering spurs, flowering becomes maximally uninhibited with advanced age.
What other flowering tree flowers better and better the older it gets? Cornus mas is some kind of a role model.
Here's how to grow Cornus mas, itself. The hardiness and handling of Cornus mas 'Fastigiata' are the same.