A Gardening Journal
Flower Buds of the Scots Elm
- Published: February 20 2017
The winter flowerbuds of my dwarf weeping elm are all the more exciting for being so close at hand: the tree's entire canopy is still just three feet top to bottom. I'm looking forward to a close study of its flowers as they mature early this spring.
There's no such right-at-handness with the canopy of the golden Scots elm. If allowed to grow free-range, this stiffly upright tree could reach one hundred feet. Even when pollarded, as below, new stems can lengthen to ten feet their very first season. Worse, because they grow upward from the top of the trunk, not outward or downward, the buds and flowers would be inconveniently high even if the stems grew only half as long.
From the ground, it's difficult to see the buds on the branches so high up. As is typical for woody plants, Ulmus glabra 'Aurea' forms two kinds of buds to carry the stems through the winter until growth resumes in spring: vegetative buds produce more stems and leaves, whereas reproductive buds produce flowers. Without question, the branches bear many vegetative buds, because the tree will absolutely burst into leaf in spring, as it has for many years already.
Are there any flower buds? If the weeping elm is any guide, they will look much different than the vegetative ones: striking series of BB-sized balls along the branches. To determine if any of the buds of the Scots elm are the reproductive type, I clipped a few stems off at their bases. Because they all originated from the top of the pollard's trunk, which is just six feet tall, harvesting them didn't require a stepladder. Then I brought the stems indoors.
The one below is representative of growth that is two seasons old. This makes sense, in that I had omitted last year's pollarding so I could follow the growth cycle of pollarded branches from first-year growth to flowering maturity. Stems that form the first season after pollarding are unbranched wands; the second season brings additional length plus the side branches you see below.
Now it's late February after the second full season of growth—and, in two months, the start of the growing season of the third. What's the progress toward formation of those reproductive buds? Alas, a close-up of a typical twig shows only pointed vegetative buds.
Below is the close-up of the lone twig on any of the branches I harvested that displayed even one of the rounded reproductive buds.
I returned to the garden to stare up into the height of the tree's canopy. The growth there is the most fully exposed to the greatest duration and intensity of maturity-inducing sun. Now that it was clear that flower buds of Ulmus glabra 'Aurea' are similar to the showy flower buds of Ulmus pumila 'Dwarf Weeper,' I had a better handle on what I was looking for as I gazed skyward into the canopy of this Ulmus glabra 'Aurea'. Nope, not a single other flower-producing "BB bud" is visible.
If no reproductive buds are showing two years after that last pollarding, how much more time would be needed for this growth to reach reproductive maturity? Another year? Two? By that time, these branches could be fifteen to twenty feet long, making a telephoto lens—or a jet pack—necessary for close appreciation of the floral display.
To see—literally—if the flowers were worth the wait, I have no choice but to allow at least some of these branches to keep maturing—and growing higher and higher in the process. If the early-spring display of buds and flowers proves worth such a long wait, I'll delay pollarding those branches until later that spring, after their flowers are done. But if I wait to pollard the entire canopy the year or two needed for all the branches to have finally begun flowering, the cycle of pollarding will be lengthy, indeed: three or four years. Worse, the pollarding would no longer be a matter of clipping off ten-foot wands that tumble to the ground harmlessly. Instead, I'd be sawing off fifteen- and twenty-foot limbs. Ugh.
I'm hoping it will be a better strategy to become a pollarding gradualist. I'll leave all of this pollard's thickest (hence tallest, oldest, and most likely to develop buds) branches in place until they flower, no matter how many years hence that will be. Then I'll cut them back to stubs in mid- to late spring. Each spring thereafter, I'll cut back to stubs any other flowering branches after their floral display is done. Meanwhile, this winter or spring and for two more to come, I'll cut back to stubs the skinniest third of the remaining branches from my two-years-ago pollarding. These aren't likely to flower for a few years anyway, and sacrificing their floral display ensures that some new vegetative growth is formed each season as I get the gradualist scheme up and running.
Lastly—whew!—I'll leave the resultant sprouts from all of this year-by-year pruning to grow freely, in hopes that in three years or so, the oldest of them will begin flowering. In a few years, each spring should bring a display of some branches in flower, even as the overall character and scale of the tree remains that of a pollard, not a free-ranger. True, it will still be a question of whether or not those flowering branches will make enough of a display to be visible right there in the garden, and without the help of a ladder or telephoto lens.
I've long ago proved how glorious Ulmus glabra 'Aurea' is when grown as a pollard of exclusively vegetative growth. Can this tree be handled practically and attractively as a pollard that flowers? Will it be worth the year-after-year effort to achieve a balanced proportion of vegetative and reproductive growth that, overall, is compact enough to be called a pollard, and yet floriferous enough to be celebrated for the seasonal floral display?
The experiment is entering its third season with no answer in sight. In a few years more, we'll know.
Here's how to grow golden Scots elm.
Here's how lengthy and vigorous the first-year growth of a pollarded Scots elm is.