The various species of bamboo may have been more popular during the late 1950s and early '60s, but have never been common. These species, of course, do not include the more common cultivars of heavenly bamboo, Nandina spp., which are not bamboo at all, but are more closely related to Mahonia spp. (Please forgive my Latin.) Real bamboo are very large grasses that spread by horizontal subterranean stems known as stolons from which tall vertical stems emerge. Branches and foliage emerge from distended nodes higher on the vertical stems. (Most texts describe the subterranean stems as "rhizomes." However, rhizomes, such as those of lily of the Nile, produce adventitious roots regardless of nodes. Stolons produce roots primarily at nodes.)

Bamboo is either "clumping" or "running." Clumping bamboos spread by stolons just like running bamboos, but do so much more slowly because the stolons' internodes (spaces between nodes) are much shorter. Internodes of running bamboo stolons are much larger, so shoots may appear several feet away from the immediately previous shoot of the same stolon.

Most bamboos are less than 20 feet tall, but some grow as tall as 40 feet. Each vertical stem emerges with the maximum stem diameter and will not become wider as it grows vertically. Growth can be very rapid—some timber bamboos can grow several feet in a day! However, bamboo requires a few years to become established and growth will be relatively slow during this time. Individual stems are only viable for a few years and should eventually be removed as replaced by new stems. Foliar litter may be profuse, but provides clean mulch that inhibits weeds.

Although notoriously aggressive and invasive, bamboos are not difficult to contain. Stolons disperse near the soil's surface, but not below approximately 18 inches and can therefore be contained by any 18-inch deep barrier resilient enough to withstand occasional prodding by the strong stolons. Most are easily deflected by sheet metal barriers, but stronger bamboo, such as timber bamboo, may require more substantial barriers.

Unwanted bamboo is most effectively eradicated by removal of the stolons. This, of course, sounds simpler than it is. Roots and stolons are fibrous and tough. Fortunately, and contrary to popular belief, bamboo cannot regenerate stolons from roots alone. Roots left in the soil will simply decay. Inaccessible stolons under decks or within expansion joints of concrete pavement may be killed by translocated herbicides applied to foliage permitted to partially mature. Such herbicides are most effective if "painted on" without dilution.

Stolons may otherwise be "starved" by removal of culms (new shoots), which are easily broken from stolons while young and tender. This procedure is not as immediately gratifying as removal of the stolons and requires diligence. A stolon may survive for a year or more without foliar sustenance and may partially regenerate if only one culm matures.


Flower of the Week: Angel's trumpet

Traditional angel's trumpet, Brugmansia spp., blooms with single or double white flowers that are especially fragrant in the evening. More contemporary yellow and pink blooming cultivars that lack fragrance are now more popular. The large flowers hang vertically from branches.

Angel's trumpet grows as a large, coarse shrub but can be pruned as a small tree. Regular irrigation and almost full sun exposure are preferred, but considerable shade is tolerable. Autumn growth is easily damaged by even slight frost during winter.

Horticulturist Tony Tomeo can be contacted at 408.358.2574 or at LGHORTICULTURE@aol.com.