Bamboo that I planted as a screen is now creeping over property lines into my neighbor’s garden. How can I stop its spread, and what’s the best method for containing a bamboo at planting time?
Valerie Borza, Weirton, WV
Bamboos that run should be contained with a strong barrier.
Photo/Illustration: Steven Cominsky
Betty Shor, coeditor of the journal Bamboo, replies: There are about 1,400 species of bamboo, from miniatures that are 2 feet tall to giants 100 feet tall. Keep in mind that, as garden plants, some bamboos are “clumpers” and others are “runners.” Clumping bamboos send up new shoots a few inches from the main clump, so it takes more than 20 years for them to expand to a circle of 8 to 10 feet in diameter.
Many of the runners can endure lower winter temperatures, so they are grown more widely. Runners have underground stems called rhizomes, which grow from the basal clump as far as 20 feet in any direction before they send up new shoots. From these extended locations, new rhizomes will just keep going—in all directions. Clearly, these bamboos require containment.
To contain a running bamboo at planting time or to corral one that’s already in the garden, dig a trench completely around the clump’s intended limit. Cut off any unwanted rhizomes on plants that have already spread too far. The roots of bamboo plants do not extend deeper than about 2 feet, so a 3-foot-deep trench will suffice. Then you must confine the bamboo with a barrier. I recommend using plastic sheeting in long rolls of at least 0.030-inch thickness and 36 inches wide. The plastic barrier should be placed in the trench, slanting somewhat outward at the top; this positioning deflects the rhizomes upward. The ends of the plastic must be joined together tightly with tape to keep the rhizomes inside the barrier.
But that’s not the end of the story. Check the barrier at least once a year, and pull out sneaky shoots that have extended over its edge; new ones should be easy to pull. Also, please note that herbicides and poisons do not work on bamboo. To learn more, visit the Web site of the American Bamboo Society at www.americanbamboo.org.