Kirby Road drapes itself across the hills and valleys of McLean, Virginia, a Washington DC suburb in northern Fairfax County and among the most affluent communities in the country. In the summer, both the trees and the topography shroud the majority of the palatial homes that line either side of this former country lane. In the winter, the topography can only obscure these residences to a limited extent; the trees are bare, and the majesty of the homes of Washington DC’s elite is visible to all. But a few peculiarities emerge, which are probably even more obvious to the uninitiated—those who don’t travel Kirby Road on a regular basis. And here’s one of them:
It’s a stand of lush greenness at a low point in Kirby Road’s elevation, when it slopes down and parallels a small tributary called Little Pimmit Run. Quite a contrast from everything else.
Given that the photos come from early March in northern Virginia, one doesn’t exactly expect such verdure. Sure, it’s not the dead of winter anymore—by this point, many trees are starting to show vestigial buds—but nothing is blooming yet aside from some snowdrops and crocuses, neither of which appear to be all that popular in this part of the country. The first time I drove past this little oasis, I genuinely thought this was some weird microclimate. I’m not sure if this hints at my own climatological ignorance more than the actual conditions, but I genuinely couldn’t figure out what caused this lush growth. Here’s the remaining Kirby Road streetscape:
The small bridge spans the Little Pimmit Run. But there’s no green to be seen. Just that little stand, or grove, or whatever you want to call it, on the side of Kirby Road opposite Little Pimmit Run.
I braved the verge of Kirby Road—twisting, undulating, lots of blind corners—to get closer to these plants to see what they were.
And it soon became obvious: they are a species of bamboo. The columnar stem structure is so distinctive that it impresses itself upon the memory. Technically, bamboo is a grass, but it’s too big and segmented for the botanically untrained eye to make such a distinction; nonetheless, introduce bamboo to a six-year-old and he or she will spot it henceforth. Furthermore, the evergreen character and rhizome cellular formation both ensure that bamboo, when harnessed competently, can serve as an excellent screen and sort of privacy fence. Lastly, it’s among the fastest growing living things in the world; though the transportation of mature plants can be cumbersome, some waist-high starters can grow to towering giants in just three years. The advantages of bamboo are therefore numerous: it’s aesthetic, it’s taller than most shrubs, and, depending on the variety, it can be low maintenance.
From what I can tell, over a dozen bamboo species are available in the United States, though most species are not indigenous. Although most prevalent in southeast Asia and central Africa, at least a few varieties have flourished in North American climates colder than the southeastern US, due to colonial introduction. This guide to the most common species isn’t enough to help me identify exactly what I encountered along Kirby Road, but I can at least deduce among a few of the options in the cited table. It is almost certainly a clumping (non-invasive) species, since these require considerably less maintenance, due to slower and more moderated growth. Running bamboo, by contrast, grows quickly, erratically, and leapfrogs over other flora. It is invasive. Without an abiotic barrier, it is likely to encroach into other turf, including that of the neighbors. Given the absence of planters or some other ceramic impediment, the Kirby Road bamboo is almost certainly one of the eight of so clumping species common to the continent. Equally important are the climatological conditions suitable for bamboo. As indicated earlier, bamboo can survive in the cold but the larger specimens tend to favor warmer climates. Though a few species can grow in the northern portions of the humid continental Köppen climate classification zone, they rarely thrive; no species are indigenous to Canada or mainland Europe. The US Department of Agriculture provides cartographic Plant Hardiness Zones that correlate to various regions, based largely on plants’ survivability in accordance with that region’s typical minimum temperatures. By the country’s overall standards, northern Virginia is hardly a place that one associates with frigid weather, but it gets cold enough that its USDA Plant Hardiness Zone is 7b, anticipating a winter temperature that bottoms out at 5-10º Fahrenheit (-15 to -12.2º Celsius). This zone accommodates some bamboo varieties, but quite a few are likely to perish at sustained temperatures below 20º F, a condition that usually happens every two to three winters in Fairfax County and McLean. The most common specie in North America, giant timber bamboo or Oldham’s bamboo (Bambusa oldhamii) thrives within the USDA zones of 8 to 11. Caveat emptor to the homeowners seeking it for a privacy screen; a cold snap could destroy it.
That said, it’s quite possible that giant timber bamboo is what I discovered there on Kirby Road. Though far from ideal, this specie is more appropriate than any of the others: the most cold-tolerant varieties are far too short, while oldhamii grows to the levels visible in these photos (from 40 to 65 feet). Additionally, the only varieties with the right combination of height and heartiness tend to be running rather than clumping. The only other reasonable possibilities for Kirby Road are seabreeze bamboo (Bambusa maligensis) or Buddha’s belly bamboo (Bambusa ventricosa), both of which are similarly cold tolerant…potentially better. However, seabreeze does not grow nearly as tall (it maxes out at 35’) and Buddha’s belly is rare in the US outside of Florida, California, and Hawaii; significant frost is lethal.
The homeowners here in McLean obviously did their research. Without giving away too many details, they’ve planted it along both roads that abut their property. It doesn’t grow to quite the same heights on the side street, but the right side of this road makes it obvious how effective it can be, even compared to the verdant winter quality of shrubs on the left side of the road.
I’ve deliberately avoided any angles that allowed me to peer through gaps in the green bamboo screen; normally I have no problem taking photos of homes from public rights-of-way, but these folks have clearly made every effort to obscure their home and yard, even in the dead of winter. I can respect this.
So the bigger question remains: why did these homeowners choose bamboo, and why is it so uncommon in northern Virginia that this example will turn heads? (Or at least, why did it turn my head?) Easy: it’s rare because the up-front costs can be considerable. Few nurseries carry bamboo, thereby amplifying shipping costs. Additionally, deer and rabbits find young, tender bamboo quite tasty, and these critters, highly adaptable to habitat fragmentation in suburban areas, are obviously abundant in Fairfax County. Lastly, this part of Virginia is just a bit north for the most popular bamboos to survive (the really tall ones); unless a homeowner is willing to compromise with a specie that only grows up to 15’, he or she will have to settle for giant timber, seabreeze, or Buddha’s belly (maybe one or two others), nearly all of which can get wiped out through an unusually harsh winter. Giant timber bamboo can easily sell for $250 a plant when purchased in bulk (20 or more); this property on Kirby Road had hundreds, resulting in what I’d estimate carried a minimum $50,000 price tag. This is a hefty price for those six extra months of a green screen. But this is McLean. With median household incomes well over $200,000, most folks can afford bamboo. And when they get those serious cold spells twice a decade, just bring in the new stock.