Black bamboo (Phyllostachys nigra) is a visually striking plant, but it is highly invasive. This species is classified as a running bamboo, notorious for its aggressive and rapid spread in garden settings. If not contained, black bamboo quickly colonizes a landscape, sending shoots far from the original planting location and potentially invading neighboring properties.
The Mechanism of Spread: Running Versus Clumping
Bamboo invasiveness is defined by the structure of its underground stems, called rhizomes. Bamboo is separated into two groups based on these characteristics: running and clumping. Black bamboo, belonging to the genus Phyllostachys, has leptomorph, or “running,” rhizomes.
Leptomorph rhizomes are long, thin, and travel horizontally through the soil, sometimes spreading 20 feet or more in a single growing season. These rhizomes store energy and produce new culms, or canes, at nodes along their length, allowing the plant to rapidly colonize new territory. In contrast, clumping bamboos possess pachymorph rhizomes, which are short, thick, and curve upward close to the main plant, resulting in a tight, non-aggressive mound.
Proactive Prevention and Containment Measures
Homeowners determined to plant black bamboo must implement physical barriers immediately upon planting. The most reliable method involves installing a high-density polyethylene (HDPE) root barrier specifically designed for bamboo. This barrier should be a minimum of 80-mil thickness, as thinner materials are susceptible to puncture by the rhizomes.
The barrier must be installed in a trench dug at least 30 inches deep to intercept downward-traveling rhizomes. It is important to leave the top two inches of the barrier exposed above the soil line. This exposed lip forces any contacting rhizomes upward, where they can be monitored and easily cut back before they escape over the top. Regular maintenance is also necessary, including annual perimeter trenching or mowing a wide area around the planting to sever any runners that attempt to bypass the barrier.
Strategies for Removing Established Invasive Stands
Removing an established stand of black bamboo is a labor-intensive, multi-year process focused on exhausting the plant’s underground energy reserves. The primary non-chemical approach is “cut and starve,” which involves cutting all above-ground culms down to ground level. This continuous removal prevents the plant from photosynthesizing and replenishing energy stored in the rhizome system.
New shoots must be repeatedly mowed, cut, or snapped off as soon as they appear, often throughout the entire growing season and for several consecutive years. For quicker results, physical excavation is the most effective method, using heavy equipment like a mini-excavator to dig up and remove the dense mass of rhizomes and soil. Chemical control is an option, where a systemic herbicide like glyphosate can be applied directly to freshly cut culms using a cut-stump application method. The herbicide must be applied within minutes of cutting to allow the plant to draw the chemical down into the rhizomes.
Lower-Risk Bamboo Alternatives
For gardeners seeking the distinctive look of bamboo, several clumping alternatives are available. Species in the genus Fargesia are recommended, as they possess pachymorph rhizomes that expand slowly, typically only a few inches annually. These varieties form tight, well-behaved clusters and do not require root barriers.
Popular options include Fargesia rufa (‘Green Panda’), which is cold-hardy and forms a dense, cascading fountain of foliage suitable for smaller gardens. For a taller privacy screen, Bambusa textilis ‘Gracilis,’ known as Slender Weaver Bamboo, is a tight clumper that can reach significant heights. These clumping species offer the desired aesthetic while mitigating the maintenance concerns associated with Phyllostachys nigra.