In the Garden:
Can't you just hear this bamboo rustling in the breeze?
Bamboo is one of the more evocative plants. A clump of tall, swaying bamboo is captivating, with its lovely, distinctive foliage. Through its association with Asian gardens, it seems to invite contemplation. The sound of the culms (stems) gently rubbing against each other is one we try to imitate in our gardens with bamboo wind chimes and fountains. The plant seems a bit exotic, especially to a New Englander. But even northern gardeners can escape to their own grove of bamboo.
Some people might argue that bamboo invites anything but contemplation. They are more apt to be cursing an aggressively spreading stand that seems to defy all methods of restraint. (Bamboos are in the grass family, after all!) But, although many hardy bamboos are the running types (potentially invasive), there are some clumping types that will not take over your yard. And there are standard methods of containing those that try.
With more than 1,400 named types of bamboo, every continent except Antarctica is home to one species or another. There are bamboos with culms of green, black, purple, red, or orange; foliage in green, white, yellow, or variegated. Some have a white stripe at each joint of the culms ... very striking!
The giant timber bamboos can grow over 40 feet tall, while some ground cover types barely reach 3 feet high. Although the giants are native to warmer climes, if you have the space and inclination to plant a tall grove, Phyllostachys nuda grows to 34 feet and is hardy to zone 5. For smaller landscapes, the hardiest types are Fargesia murieliae and Fargesia nitida, both of which grow to about 12 feet. But even some plants that aren't rated as hardy in our region will grow here because although the tops may die back, the roots typically survive and resprout every spring. I've grown the 4-foot-tall Pleioblastus fortunei in my zone 4 garden for years even though some sources rate it hardy to only 10 degrees F. So, go ahead and push the envelope.
Bamboos thrive in most any soil type except for heavy clay soil that's easily waterlogged. Even in New England most bamboos grow better if they receive some shade during the hottest part of the afternoon. Especially on the roots. Like clematis, they need a thick layer of mulch covering their roots, and any leaves they shed at their feet should be left there to decompose and provide needed silica and other nutrients.
When newly planted, bamboos need lots of water and fertilizer, and protection from the wind. Transplant them right before a rainy spell, if possible. The tall varieties need staking for the first year, and what better to use as stakes than ... you guessed it! Allow the culms some movement or they may break in heavy wind or snow. Even a mature clump can bend in a heavy, wet snowfall, so be prepared to shake the snow off when necessary.
Interestingly, a culm doesn't grow in diameter as it ages the way other plants do; it always stays the same diameter. In a young plant, the culms may be spindly. It can take a few years for a clump to become established and for the new culms to emerge thick and strong. When in top form, a culm can set growth records, growing a foot or more in height in one day! Oh, but don't expect that in New England, where cooler temperatures slow their growth.
Clumping or Spreading
Bamboos may not grow to their full potential in our region, but that also means they don't become invasive as quickly. Clumping types don't present any problems, and if you want to cover a large area with bamboo, the spreading or running types won't either. But if you fancy a running type yet need to constrain it, there's a lot of information about different approaches to take.
In China bamboo is sometimes restrained from spreading by surrounding a grove with a ditch of water because bamboo won't spread through the water. Knowing this, a friend planted her streamside with bamboo to stabilize the banks without worry of it jumping across to where she didn't want it. Lacking a water boundary, you can dig a ditch around the planting and keep checking it to cut off any rhizomes in sight. But the most dependable control measure is to put up a barrier underground around the perimeter of the planting.
Bamboo spreads by underground rhizomes, and they will grow at the depth at which there's the most organic matter and soil amendments. Here's one situation where you'll be penalized for doing a great job of improving the soil deeply to encourage deep rooting. With running bamboos, don't add amendments any deeper than about a foot. Then you can most likely get away with setting your barrier about 18 inches to 2 feet deep, although some experts recommend going down to 30 inches to be safe.
Choose a material for the barrier that won't allow the rhizomes to penetrate. Some options are concrete, metal, plastic, or thin fiberglass sheeting used to cover greenhouses. Easiest to use is high-density polypropylene, 40 mil or heavier, called "root barrier" or "rhizome barrier." Dig a trench around the perimeter, set the barrier in place and fasten it together at junctions. Then pack soil around it. Leave a few inches of the barrier above ground to thwart any surface rhizomes.
Another approach is to grow a single plant in a large container that's buried in the ground. The lower half of a plastic garbage can with drainage holes cut into the bottom will work. Line it with screening material so the rhizomes don't escape through the holes. You can grow the smaller bamboos as container plants and move them inside for the winter.
That said, my running bamboo hasn't proved to be a nuisance even without a barrier. Perhaps that says something about how rich the soil in that area isn't, but I also attribute it to our relatively short growing season, which discourages plants from getting too much of a running jump.
Hold the Flowers
Bamboos have curious flowering habits. Some types rarely flower, and once they do, they die. Usually. And close relatives tend to flower around the same time. According to the Bamboo Garden Nursery, some plants of the Fargesia nitida variety flowered within the past few years for the first time since it was introduced in the 1880s, so there's a chance that other named forms of this variety that are currently planted will flower and die within the next few years. For those with a future legacy in mind, the nursery offers some new Fargesia seedlings with no risk of flowering for the next 100 years.
Eating Shoots and Leaves
Some varieties have tastier shoots than others, and some produce more long-lasting poles than others. If you're interested in these types, you can get more information from the American Bamboo Society (http://www.americanbamboo.org).
Then all you'll need to complete the ambiance is a pet panda ...
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