Bamboo- Runners and Clumpers

Broadly, ornamental bamboos divide into runners" and "clumpers." Both expand by sending out rhizomes, but the runners' rhizomes reach out much farther before they send up shoots. Even in their second or third year, runners will poke up shoots 4 or 5 feet from the main clump; at maturity some of the timber giants will send up shoots 20 feet from the nearest stalk.

Clumpers put out shoots much closer to the main bunch and spread more slowly. My five-year-old clump of punting pole bamboo has expanded only about 3 feet in every direction since I planted it. Each year new shoots appear around the periphery of the clump but never more than a foot from the nearest culm.

Clumpers are self-limited and no more of a problem than any other tree or shrub of the same size. However, most of the clumping bamboos are from warm climates; the hardy bamboos, such as the genus Phyllostachys, are often runners.

The easiest way to slow the growth of bamboo is to restrict its food and water. If you confine it in a pot or planter or behind a root barrier, bamboo will remain small.

Bamboo's spreading is easy to control because of another botanical peculiarity. There are a limited number of buds on each rhizome, each capable of producing just one culm. Each bamboo shoot is built like a jack-in-the-box; all its nodes are already present in compressed form when the shoot first pokes its head up. If you slice through a newly emerged shoot, you can count the number of segments the culm would have had. The practical effect is that, if you cut off a bamboo shoot, it doesn't resprout.

I find the best weapon against bamboo springing up in my lawn is a lawn mower. Just mow down the shoots with the rest of the grass; after a couple of mowings, the shoots give up.

If you want, you can build a barrier around the planting to stop the plant from running. With timber giants a trench about 3 feet deep is sufficient; either leave it exposed, fill it with leaves (and search through it every spring for new rhizomes) or install a barrier and backfill the trench. One of the best barriers is the aluminum flashing sold in home centers for roofing (just don't leave gaps or unsealed cracks). It is especially effective if angled away from the plant; rhizomes that reach the barrier are directed up toward the surface.

Click to view cart