The flowering habits of bamboos have puzzled botanists all over the world for years. Some species of bamboo flower all at once – wherever they are in the world – and then die. Bamboo renews itself each year by sending up new shoots from underground stems. Each plant flowers only once in its life, then, its life cycle completed, it dies. But occasionally, at intervals of between 40 and 120 years depending on the species, the plants flower, seed and die en masse.
Sometimes the insignificant blooms appear on only a few stems of one plant, and although those particular stems die, the plant as a whole is unaffected.
Sometimes, on the other hand, the whole plant is weakened or dies. And sometimes entire forests can be killed off in this way. In one such flowering, in China’s Qionglai Mountains in May 1983, much of the region’s forests of arrow bamboo died. And an unknown number of giant pandas, which depend on bamboo for food, starved to death as a result.
Instances have also been known where tender bamboos grown for years in British greenhouses have suddenly flowered – and died – at roughly the same time as large numbers of plants of the same species growing wild in the tropics.
Generally, not all of the bamboos within a species flower, and so the species can survive. Moreover, many of the seeds formed in the flowers do in time germinate to grow into a new generation. A few years ago, however, a beautiful variegated bamboo (Sasa kutilensis variegata) did become extinct through this mass flowering and dying phenomenon. Collected seed was germinated, but the resultant plants did not possess the attractive golden leaf variegation.
If your own bamboo plant begins to produce flowers, there are two rescue options, either of which may save it – although neither method has won universal support from horticultural scientists.
First, you could try feeding it. Research carried out at the Pacific Bamboo Garden Nursery in California suggests that if bamboo plants are fed liberally with a high-nitrogen fertiliser, such as hoof and horn meal, at and after flowering until new growth appears, there’s a good chance that they will survive. But nobody yet knows whether this method will work on all bamboo species or in all climatic zones.
Second, you could try preventing it from flowering. Some older gardeners claim that the lives of bamboos can be saved by cutting all the stems down almost to ground level at the first sign of any flowers.