Bamboo, a member of the grass family, can indeed be cultivated successfully in Wisconsin, but only by selecting specific, cold-tolerant varieties. The success of growing this plant in a northern climate hinges entirely on choosing a species whose underground root structure can endure the state’s severe winter temperatures. For gardeners in Wisconsin, the challenge is not just keeping the canes green, but ensuring the long-term survival of the rhizomes deep beneath the frozen soil. By focusing on highly resilient species and implementing deliberate, specialized care, it is possible to establish a healthy, thriving bamboo grove or screen.
Understanding Wisconsin’s Climate and Bamboo Limits
Wisconsin’s climate presents a significant hurdle for most common bamboo species due to its consistently low winter temperatures. The state generally falls within USDA Plant Hardiness Zones 4b, 5a, and 5b, where the average annual extreme minimum temperatures drop to between -25°F and -10°F. This deep, sustained freeze is the primary factor limiting bamboo selection, as the root system, or rhizome, must survive below the frost line. Most tropical bamboo varieties cannot withstand temperatures below 20°F, making them unsuitable for Wisconsin gardens. Successful cultivation requires choosing species whose rhizomes can tolerate cold down to at least -20°F, or even lower, as this extreme cold tolerance must be genetically inherent for the plant to emerge in spring.
Selecting Cold-Hardy Bamboo Species
The rigorous requirements of Wisconsin’s climate narrow the choice of viable species to a select group of durable temperate bamboos. One of the hardiest and most reliable options is Phyllostachys nuda (Naked Sheath Bamboo), a running variety that is famous for its ability to withstand root temperatures as low as -20°F. It develops dark green culms, or canes, and can reach heights of 10 to 34 feet depending on the zone and growing conditions. Another highly cold-tolerant runner is Phyllostachys bissetii, rated for Zone 4, which is known for its dense, dark green foliage that holds color well through the winter. For those seeking a non-spreading option, the Fargesia genus offers several clumping species, such as Fargesia rufa, which is hardy to about -15°F, though these varieties remain shorter (5 to 10 feet), making them better suited for mid-sized shrubs.
Managing Aggressive Spread: Running Versus Clumping Types
Bamboo species are categorized by their underground growth habits: running or clumping, a distinction determined by their rhizome structure. Running bamboos send out long, horizontal underground stems that can rapidly travel many feet from the parent plant. These varieties, like Phyllostachys nuda and P. bissetii, are typically the most cold-hardy but require strict containment to prevent aggressive spread into lawns or neighboring properties. Clumping bamboos, such as those in the Fargesia genus, feature short rhizomes that curve upward to form new culms close to the original plant, resulting in a dense, predictable clump that expands slowly and does not require underground barriers. If running bamboo is chosen for its superior cold tolerance, containment is achieved by installing a specialized high-density polyethylene (HDPE) rhizome barrier, which should be 60 to 80 mil thick, installed vertically 30 to 36 inches deep, with two inches left above the soil line.
Essential Winter Preparation for Survival
Successful long-term growth in Wisconsin depends heavily on preparing the bamboo for the sustained freeze and winter desiccation. Before the ground begins to freeze solid in late fall, it is crucial to give the plant a deep, thorough watering. This ensures the rhizomes and culms are fully hydrated to withstand the drying effects of cold winter winds, a phenomenon known as winter burn. Once the soil cools, applying a heavy layer of protective mulch is the most practical step for root insulation. An application of wood chips, straw, or shredded leaves, 6 to 8 inches deep, will help buffer the soil temperature and prevent the root ball from reaching its extreme minimum temperature. For young bamboo, temporary windbreaks constructed of burlap or snow fencing can significantly reduce wind exposure, and any canes suffering cold damage should be left until spring to protect the underground rhizome system.