Clumping vs. Running Bamboo
Bamboo is classified by its root system. There are two basic types, clumping bamboo and running (invasive) bamboo.
Clumping bamboo is easily contained and are considered non-invasive. They are incapable of expanding more than few inches a year and will generally form compact, circular clumps. They have a very short root structure that is close to the surface. The clumps slowly enlarge as new shoots emerge every year, emanating from the original planting. Depending on species, clumping bamboo will ultimately expand anywhere from 3 to 10 feet in diameter (or more for taller varieties) in order to reach their mature height. Clumping bamboo can grow densely with both canes and foliage and is a good choice for privacy hedging.
Running bamboo can be difficult to control and is considered invasive causing concern for neighbors and communities. This is the only type of bamboo that predominantly grows outdoors in northern climates. It can sprout new shoots from the ground a distance away from the plant that is equal to its height. A ten-foot plant can send a shoot up ten feet away from the original cane! Running bamboo can also spread up to several yards during a growing season. Containment of invasive running bamboo is possible with planning and below grade retaining 'walls' or large above ground planter boxes.