How Bamboo Grows

Bamboo grows in fits and starts. For much of the year nothing much appears to be happening, and then in one brief season they explode with growth.

During the late summer, fall and early winter most temperate species manufacture and store sugars in their underground rhizomes. In addition to fine root hairs, rhizomes produce buds that develop into new rhizomes. In spring (and sometimes in late winter), rhizomes pump accumulated energy into new shoots (or culms).  Each culm breaks through the soil surface being the same diameter as its final mature diameter, and culms achieve all of their height in about 30-60 days. The branches fold out from the culm and leaves develop in another 30-60 days. (Shoots of some species in mature tropical groves have actually been clocked growing 4 feet in one 24-hour period!)

As a young plant’s rhizome system expands, its ability to produce larger, taller and more numerous culms increases. Thus, each year’s “crop” of shoots is larger than the last, until the mature size for the species is reached and new culms continue to come up at the mature sizeIt may take a number of years to reach this point, depending on the size and age of the original planting, the species and the growing conditions.

The shooting period varies from species to species and genus to genus. In general, the temperate climate bamboos are runners, which shoot in the spring, while the tropical and sub-tropical varieties are clumpers, which shoot in the late summer and fall.

Individual culms and rhizomes only live an average of 5-10 years, and the culms grow no taller or bigger with age. That is why the older parts of the plant are frequently the smallest. Old culms (smaller) or dead culms can be thinned out to make more light available for new growth.

When purchasing a bamboo to transplant, be aware that what you are really paying for is well established and well developed rhizomes in the root ball.  This will give you a head start, but even so the first year or two after transplanting you will not see tremendous above-ground growth, as the plant is putting most of its energy into its root system and getting used to it’s new home.

Gregarious Flowering… the fascinating life cycle of bamboo

Flowering Schizostachyum glaucifolium

One of the mysteries of bamboo is how many species flower periodically all over the world at the same time. This is called “complete gregarious flowering.” Flowering may continue for 2 to 7 years and is eventually fatal to the mother plant. This was the case with the giant Phyllostachys bambusoides when it flowered during the 1970′s, as it has done every 120 years through recorded bamboo history. Being an important timber variety, records of its flowering go back multiple centuries. Many mid sized bamboos have 60-75 year flowering cycles, and small bamboos have a much shorter cycles.

Gregarious flowering is not well understood. In some cases species go into partial flowering (meaning not all plants of that species go into flower in the same time frame), and in some cases individual plants go into flower all by themselves, triggered by environmental conditions such as drought or stress. Some postulate that both of these occurrences are precursors to complete gregarious flowering.  Bamboo Sourcery does not sell plants that we know to be going into flower, gregarious or otherwise, however adequate records do not exist to predict when most species will flower.

In some cases, with extra care and feeding, the mother plant may survive flowering.  In addition, the numerous seeds, if fertile, may be planted and will reproduce genetically identical plants or in rare cases can produce new and interesting variations through natural mutation. By the time the mother plant finishes flowering, you may already have new seedlings well on their way!

Bamboos belong to the grass family, and their flowers look a lot like the flowers of other grasses, usually nothing spectacular, but quite varied. Traditionally, botanists describe species on the basis of their flowers. Because the flowering interval of some bamboo species is so long, botanists in the field often have difficulty finding flowers and defining species on that basis. This sometimes results in multiple names for the same plant and a great deal of confusion. Promising genetic research and international cooperation should help clarify the situation.