Clumping vs Running Bamboos

There are two main types of bamboo: Noninvasive clumping bamboos (sympodial or pachymorph) have short roots and form discrete clumps. There are also a few species of clumpers which have slightly longer roots (6-18″), and we refer to these as open clumpers. Running bamboos (monopodial or leptomorph) are the ones that spread through the growth of long, horizontal roots, called rhizomes. With a little knowledge and proper materials, running bamboos and open clumpers can be effectively contained. The information in this guide will enable you to grow beautiful, well-behaved bamboo.

CLUMPING BAMBOO

Clumping bamboos have a very short root structure, are genetically incapable of expanding more than few inches a year, and will generally form discrete circular clumps. The clumps slowly enlarge as new culms emerge every year, but may ultimately need to expand to anywhere from a 3 to 10 ft. in diameter (or more, especially for taller types) in order to reach their mature height, depending on species. The dense root system can exert strong pressure on structures in contact with it, and thus clumpers should be planted at some distance from fences, sidewalks, retaining walls, etc. Clumpers make excellent specimen plants and will also form very dense screens, but more slowly than runners. Except for the Fargesias, clumpers tend to be less cold-hardy than runners.

Clumpers grow TALL faster than runners in the absence of frost. They will stay shorter if they are planted in an area smaller than recommended, but they will need regular maintenance and containment measures to limit them if given free reign.

Clumpers are recommended for:

  • Dense screens (but slower to fill in).
  • Height: Maximum SF Bay Area height is 40 ft. in some locations, but 30 ft. on average.
  • Some of our giant timber clumpers may grow up to 55 ft. in tropical climates.
  • Specimen plants and ornamental accents.
  • Wherever spreading is undesirable, and root barrier installation is too expensive or difficult (e.g. tree roots or on steep slopes). Large, wide planting spaces or containers.
  • Clumpers may require anywhere from a 3-10 ft. diameter circular space, or more, in order reach their mature height, depending on species.
Clumpers are not recommended for: (again, these are very general guidelines and there can always be exceptions, depending on the situation)

  • For fastest screens or fill-in. (They do gain height rapidly, however).
  • Narrow planting beds or small or narrow containers, especially ceramic ones which can be broken by root pressure.
  • Clumpers cannot easily adjust their circular shape to a long, narrow space, and height of culms may be limited if too small a space is allowed for the roots.
  • Annual thinning can extend the length of time a clumper can grow in a small, contained space, however.
  • Cold winter areas which receive lots of frost or temperatures below 20 degrees F. (except the Fargesias, which are hardy to -20 degrees).
  • For wide choice of species. There are fewer clumping species to choose from for any given micro climate or sun exposure, but there are some clumpers appropriate for almost every area. About 1/3 of the bamboo species are clumpers.

RUNNING BAMBOO

Running bamboos spread variously, sending out underground runners (rhizomes) which sometimes range far from the parent plant. Runners fill in the spaces between plantings faster, making them ideal for fast screens, hedges, and the popular open grove look. Bamboo runners may be easily contained, since the rhizomes grow sideways at a depth of only about 2-18 inches. Most are also very cold-hardy.

Runners are recommended for:

  • Fast privacy screens with quick fill-in, in narrower spaces than clumpers.
  • Greatest height in the SF Bay Area – some species grow up to 50 ft. In more tropical climates, some giant timbers may reach 60-70 ft.
  • Large open groves.
  • Ground covers and erosion control.
  • Container planting.
  • Less expensive plants (but may require root barrier installation).
  • Greater variety of species to choose from.

Runners are not recommended for:

  • Situations where barrier installation is desirable but problematic (e.g. tree roots or on steep slopes)
  • Where fear of invasiveness is insurmountable.

Please see Containment of Bamboo for a complete explanation of methods of containment.

See our Price List for the many available clumping bamboos (designated by the code “C”), open clumpers (“O”), and running bamboos (“R”) that we offer.

Each individual species page on this site will show whether the species is a clumper or runner in the Additional Information tab.