hat the number of buds sprouting varies with the species of bamboo. In plantings at Camden, some species produced much better stands than others from the same number of rhizomes. Phyllostachys rubromarginata produced better stands than did P. bambusoides, P. viridis, or P. vivax.
The bud from which the new bamboo culm grows appears on the side of the rhizome as a small, hard swelling. As the warm weather of spring arrives, this bud begins to lengthen and expands into a compact upright growth until its point pierces the ground.
The new culm first makes its appearance above ground as a sharp point, and develops slowly upward for the next few days. An interesting feature of bamboo growth is that the entire length of the cane is compressed into the sprout when it first makes its appearance above ground, the elongation being from the bottom up; that is, the bottom joints or internodes elongate much more rapidly than those above, and cease growing only when they reach their ultimate length. There is no increase in girth of the bamboo culm after it appears above ground, but the culm elongates joint by joint until it reaches its maximum height. Elongation is slow for the first 2 or 3 feet, but the height growth from then on is exceedingly rapid to maturity. For example, timber bamboo growing from mature rhizomes completes its height, which may be as much as 55 feet, in 76 weeks, the average time in which all bamboo shoots reach maximum height. At this time the plant sends out branches from the nodes near the top. These produce leaves and the plant has completed its growth except for filling of the culm. The walls harden for about 2-3 years, when the bamboo culm is completely mature.
The plant sheds its leaves each summer by putting out a new crop from buds in the axil of the old leaves. Old leaves drop gradually, so the change from old to new leaves is hardly noticeable. The age of a bamboo culm can be determined by the number of leaf scars on a branch (twig). A year-old culm would have no leaf scars, a 2-year-old would have one, and a 3-year-old one would have two scars.
The first year after planting bamboo, culms are only a few feet in height. Culms originating during each succeeding year grow a few feet taller than those of the year before until the ultimate height for the species is reached. For the larger varieties this is usually 15 to 20 years. It usually requires 7 or 8 years after planting before canes large enough to be of use are produced.
The flowering and production of seed is a curious and interesting feature of bamboo. When this event occurs, many species die. Whole forests may die, requiring several years for the seedlings or vegetative parts to repopulate the region. Another phenomenon associated with bamboo is the simultaneous development of flowers. All plants of the same species, regardless of age or size, over a wide region will bloom at one time. Plants flower for 2 or 3 years and then die. A few buds usually survive at the base of a plant. The plant must be reestablished from seed or from buds that did not die.
This peculiarity of bamboo is of prime importance from an economic standpoint, for it would be unfortunate after spending time and money in the development of plantations suddenly to find the whole destroyed or so weakened that several years would be required to reestablish them. The flowering is rare, occurring only once in many years.
In reestablishing bamboo after it has seeded, some small shoots appear. These should be left for the first 3 years at least. All the shoots that appear should be allowed to mature. After the grove is once established, only the largest shoots should be permitted to grow, the others being cut as soon as they appear. This thinning process concentrates plant growth into a comparatively few large culms and gradually increases the height and strength of the forest. At Auburn since 1933, three bamboos have flowered, recovered, and reestablished themselves. The whole process required about 6 years.
Bamboo in general requires a moderately moist, well-drained soil of good fert