Bamboo is one of those ornamental plants you never expect to see blooming. And for good reason: some species can take as long as 100 years to produce flowers! Although rare, bamboo flowering is not always good news for gardeners. In most cases, it’s a sign that your plants are consigned to death row.
Most bamboo species only flower once in their lifetime. After flowering, the plants will die, often en masse. The seeds will ensure the survival of the species, and most groves usually regenerate after six years. However, some bamboo species can also regenerate after flowering through their rhizomes.
As a gardener, you may be surprised by the idea that your carefully-grown bamboo grove can one day bloom and then simply die off. However, there are a few methods you can use to manage the process, and also make the most of it, if and when it happens in your garden.
The flowering habits of bamboo
Scientists use four categories to describe the flowering habits of bamboo: gregarious, sporadic, mixed, and partial.
These categories refer to how many bamboo plants in a certain forest or area will bloom at the same time. In a small garden, a bamboo’s particular flowering habit may not stand out much. But on a large scale, seeing entire bamboo forests bloom at the same time can be spectacular, and even eerie.
Gregarious or mass synchronized flowering occurs when more than half of the bamboo plants in one area bloom at the same time. This flowering habit is common for some of the most popular ornamental bamboo genera, including Fargesia and Phyllostachys.
Sporadic bamboo flowering takes place when only a few clumps of bamboo within a larger area bloom at the same time. This phenomenon is random and intermittent, although some scientists believe it’s more likely to take place in cultivated or intensely managed bamboo species.
Some species of bamboo display a mix of sporadic and gregarious flowering habits. In these cases, you’ll notice a few clumps bloom first. The bulk of the forest will then bloom all at once, followed by the remaining clumps blooming as well.
The least common of bamboo flowering habits, partial flowering, occurs when some parts of a bamboo forest bloom sporadically, while others bloom gregariously.
How often does bamboo flower?
The flowering cycles of bamboo depend entirely on the species. Broadly speaking, scientists have divided them into three types: annual, periodic, and uncertain.
A few species flower annually or continuously, which means that they bloom and produce seeds once every year without dying in the process. But the majority of bamboo plants flower periodically, in cycles ranging from as little as 7 years, to as long as 150!
In some cases, however, the flowering frequency is uncertain and difficult to predict. For example, Dendrocalamus strictus has been observed blooming once every 8, 12, 20, and 70 years. That’s not exactly a strict flowering pattern.
Bamboo’s flowering habits can also change depending on growing conditions, with significant variations between different geographical areas. For instance, Phyllostachys edulis flowers once every 48-67 years. But in some parts of China, botanists haven’t seen this species bloom for over 200 years.
Below you can see the observed flowering cycle and flowering type for several popular bamboo species:
|Species name||Flowering cycle (years)||Flowering type|
|Bambusa bambos||30-40 / 47-52||Gregarious|
|Fargesia murielae||35 / 80-110||Gregarious|
|Melocanna baccifera||7-10 / 26-50||Mixed|
|Phyllostachys reticulata||40-60 / 100+||Mixed|
|Sasaella kogasensis “Aureostriatus”||31+||Gregarious|
Interested in other bamboo species not on the above list? Check out this resource (pg. 14+) and this one for more data on bamboo flowering habits observed around the world.
What does bamboo flowering look like?
The blossoms of bamboo, in and of themselves, are not particularly exciting. Bamboo is a grass, after all, and its blossoms resemble the feathery husks of other grasses.
The remarkable part of bamboo flowers, other than the fact that they’re so rare, is the scale on which it happens. Entire groves become laden with flowers, causing bamboo stalks to bow under the weight. The sight is quite a spectacular one.
After the initial flowering period, the blossoms will actually produce fruit, or bamboo rice. These seeds will naturally fall to the ground to generate new offspring.
Does all bamboo bloom at the same time?
Bamboo species that display gregarious flowering habits are more likely to bloom all at the same time. For example, if you have a grove of Phyllostachys edulis on your property, more than half of the plants in that grove will flower at the same time!
Meanwhile, if you have a sporadic flowering species, such as Bambusa vulgaris, some of the clumps in your grove will bloom simultaneously, while others will not.
Additionally, scientists do not expect bamboo synchronicity to be the same across all geographic regions, though there are often similarities.
What happens to bamboo plants after they bloom?
The vast majority of bamboo species die after they flower. The culms wilt after the flowers go to seed, then slowly start decomposing. Because bamboo flowers so rarely, mass die-off seems shocking. But does the same thing not happen year after year in the vegetable garden?
On the plus side, a new generation of bamboo plants will take over after the fallen seeds germinate. Most groves can regenerate from seedlings five to seven years after the seeds have set.
Scientists suggest that bamboo dies after it flowers because it’s a semelparous or monocarpic organism. Simply put, this plant is biologically designed to die after it reproduces, and there’s not much we can do about it.
Can bamboo come back after flowering?
Although most bamboo plants die after they bloom, some species can grow back vegetatively. Woody or dwarf species in particular can use their underground rhizomes to produce new shoots the following year. This includes woody bamboos such as Phyllostachys, or shrubby plants from the genus Sasa and Schizostachyum.
On the other hand, species belonging to the genus Fargesia or Bambusa are less likely to rejuvenate after they bloom.
The good news is that if you have a bamboo grove composed of multiple different species, they won’t influence each other’s flowering cycle. So even if some of your bamboo blooms and then dies, the other species will continue to send out new shoots and help your grove remain full and healthy.
There are several control methods that you can use to slow down the bamboo flowering process and ensure the chances that it will regenerate. One option is to cut down any flowering stems or culms as soon as you notice the blooms. If you have a running bamboo species, you can also dig up and cut the rhizome connecting a flowering culm to one that’s not flowering.
You’ll also want to avoid propagating flowering bamboo plants. The ‘clones’ created from propagated stems and cane will start flowering soon after becoming established, and they most likely die afterward.
Keep in mind that you can’t stop the flowering process completely. Like all living things, bamboo is genetically programmed to reproduce. If you’re lucky, some of the rhizomes may survive after the culms bloom. But otherwise, you can use the seeds to propagate a new set of plants.
How to harvest bamboo seeds
Harvesting bamboo seeds is a simple process. Seeds vary depending on the species; some can be as small as a grain of rice or encased in fruit as large as an apple. If you’re growing bamboo for ornamental purposes, you’ll most likely deal with species with smaller seeds.
In this case, the best way to harvest seeds is to cover the flowering stems with a mesh bag. When the seeds are ready, they will simply drop into the bag. Try to plant your seeds as soon as possible, as most ornamental bamboo seeds have a short lifespan.