Bamboo, often mistaken for a type of tree, is actually a member of the grass family Poaceae, making it the largest member of this botanical group. This perennial plant is highly valued for its rapid growth, which can be as much as 91 cm in a single day for some species, and its evergreen foliage provides year-round structure. Its woody, jointed stems, known as culms, make it a popular choice for creating dense privacy screens or as an architectural ornamental plant in gardens. Successfully establishing bamboo requires understanding its unique growth patterns and implementing specific planting and containment strategies from the start.
Deciding on Running or Clumping Varieties
The most important decision when starting bamboo is selecting a variety based on its underground rhizome structure, which determines its growth habit. Bamboos are classified into two main types: running (monopodial) and clumping (sympodial). Running bamboos, such as Phyllostachys, produce long, thin rhizomes that spread aggressively, sometimes up to 20 feet in a single season, making them invasive if uncontained. Clumping bamboos, including Bambusa and Fargesia genera, have short, thick rhizomes that expand slowly in a predictable clump, often only a few inches each year. Running types require proactive containment, while clumping varieties suit smaller areas or containers where spread is naturally limited.
Propagating New Bamboo Plants
While new bamboo can be purchased as nursery stock, propagation from an existing grove is common, with division being the most reliable method for both running and clumping types. Division involves isolating a segment of the plant that includes a portion of the rhizome and at least one culm, or cane, and is best done in early spring. For running bamboo, use a sharp spade to sever a section of the rhizome that has produced a new shoot away from the main grove. Clumping varieties are harder to divide due to their dense root mass, but an offset (a new shoot on the outer edge) can be separated by cutting through the connecting rhizome. The culm of this severed section should be reduced to about 30 cm to minimize water loss, then potted in a well-draining mix until new root growth is established.
Culm cuttings are a less reliable method, primarily used for clumping bamboo. This involves segmenting a cane with one to three nodes, ensuring a healthy bud or branch remains at the node. The segments can be placed directly into a rooting medium or water, sometimes using rooting hormone to increase success. Starting bamboo from seed is rare because most species flower infrequently, often only once every 12 to 120 years, and the seeds have a short viability period.
Site Preparation and Planting Techniques
The planting location should offer well-draining soil, as bamboo does not tolerate waterlogged conditions, which can lead to rhizome rot. Most bamboos thrive in full sun, though some species benefit from partial shade during the hottest parts of the day. The soil itself should ideally be slightly acidic, with a pH range between 5.5 and 6.5, and can be amended with organic matter like compost to improve fertility and drainage.
When planting, dig a hole that is at least twice as wide as the bamboo’s root ball to give the new roots space to expand into loosened soil. The plant should be set in the ground so that the top of the root ball remains at the same level, or slightly lower, than it was in its container. Backfill the hole with the amended soil, firming it gently to remove air pockets, and water the newly planted bamboo thoroughly to settle the soil around the roots. A layer of organic mulch, such as dried leaves or compost, should be applied around the base of the plant to help retain soil moisture and protect the shallow rhizomes.
Managing Growth and Containing Spread
Controlling the spread of running bamboo requires physical containment to prevent rhizomes from escaping the designated area. The most effective method is installing a vertical root barrier made of high-density polyethylene (HDPE) plastic. The barrier should be a minimum of 60-mil thickness and installed 24 to 30 inches deep, as rhizomes typically travel in the top 5 to 20 inches of soil.
Ensure the barrier protrudes one to two inches above the soil line and is angled slightly outward to redirect upward-growing rhizomes. For long-term control, perform rhizome pruning once or twice a year, cutting and removing any rhizomes that stray from the main clump or attempt to cross the soil surface. Initial fertilization with a high-nitrogen product helps new plantings establish quickly, but regular maintenance is essential for keeping running bamboo contained.