Pruning or trimming back bamboo can be used as a means for encouraging even more rapid growth.
The world record for the fastest growing plant belongs to certain species of the 45 genera of bamboo, which have been found to grow at up to 91 cm (35 in) per day or at a rate of 0.00003 km/h (0.00002 mph) (!)
All the bamboo plant needs to do, is fill the cell with (mostly) water, which bamboos, as members of the grass family, are very efficient at doing. The strategy of growth by elongation is common among grasses. Typically the roots don’t grow anymore than 50cm below the surface of the ground. Older, more established plants, usually at least 3 years in the ground, will grow faster than newly planted ones.
There are 2 methods for trimming clumping bamboo in order to encourage growth. The first is an annual trimming of older and dead culms, which allows the plant to conserve more energy for producing new shoots. Second, many bamboos require an annual pruning in order to look its best, which also serves the purpose of diverting the plant’s energy into producing more root growth and new shoots.
1) Lifecycle of the culm: As each individual culm goes through a 5– to 7-year lifecycle, culms are ideally allowed to reach this level of maturity prior to full capacity harvesting. The clearing out or thinning of culms, particularly older decaying culms, helps to ensure adequate light and resources for new growth. Well-maintained clumps may have a productivity three to four times that of an unharvested wild clump. Consistent with the lifecycle described above, bamboo is harvested from two to three years through to five to seven years, depending on the species.
2) Annual cycle: As all growth of new bamboo occurs during the wet season, disturbing the clump during this phase will potentially damage the upcoming crop. Also during this high-rainfall period, sap levels are at their highest, and then diminish towards the dry season. Picking immediately prior to the wet/growth season may also damage new shoots. Hence, harvesting is best a few months prior to the start of the wet season.
3) Daily cycle: During the height of the day, photosynthesis is at its peak, producing the highest levels of sugar in sap, making this the least ideal time of day to harvest. Many traditional practitioners believe the best time to harvest is at dawn or dusk on a waning moon.