When to harvest bamboo? - Hawaiian Islands

[Richard on Maui]

I wonder when the best time to harvest is here in the Hawaiian islands, where the driest season is the summer, when bamboo is actively shooting, and the most rain falls in the winter, and some species seem to keep shooting anyway.
Any ideas or experience from people in the islands?

[Mark Meckes]

Hi Richard,
Info I've found on harvest time for tropical bamboos is pretty generalized, considering the variation of tropical climates that exist and also the diversity of species growing in the tropics.
However one claim is to harvest following the growth of the new shoots.
The premise is that sugars and starches are diverted towards the development of the new shoots, depriving older culms of these nutrients and making them less susceptible to insect infestation.

However I would also note that older culms in a grove or planting may have already lost their ability to take up nutrients, and there are definite advantages of removing these culms prior to shoot development if overcrowded conditions exist which can hamper the growth of the new shoots.

Of course bugs and resistance varies according to location, species types and methods of treatments following harvesting.

Harvesting during the dry season certainly gives one greater control of the drying procedure, with less problems of mould and mildew which can form during wet seasons or when the humidity is too high.

Mark

[Richard on Maui]

Thanks for the comments Mark. Nice site, by the way.
I am still pretty confused, I guess, about when to harvest in this trade wind affected subtropical climate! I guess that the best time is probably after the new shoots have come up, but before the big rainy season sets in? I guess it isnt the best for the clump to thin out shoots that have reached full culm size though, huh? As that is sort of a waste of energy?
The species I am mostly interested in here are clumpers - I have just made an arrangement to maintain two Guadua clumps in exchange for material, and there is a Thyrsostachys siamnensis there, and also a Dendrocalamus membranaceous that they would probably be thrilled if I took on.
There is quite a lot of wild Phyllostachys on Maui, I guess it is aurea for the most part. Then there are the clumpers that the Polynesians brought here in their canoes, B. vulgaris vittatta. I could go get any amount of those species, but would kind of like to try to harvest some bamboo that might last beyond a couple of years.

[Mark Meckes]

Richard, that's a great selection of bamboo you have access to!
Do you have any photos of these boos? If so, click the /!\ icon at the top right and I can discuss uploading them.

BTW there's a bamboo event in Hawaii coming up ...
Bamboo Hawai'i Oct 19-23 2006: 27th ABS National Conference (http://www.bamboocraft.net/forums/showthread.php?t=1827)

I guess that the best time is probably after the new shoots have come up, but before the big rainy season sets in?

Here's some thoughts ...

Logically this makes sense as the bamboo would have the least amount of moisture that would need to be extracted in the drying process.
Practically it isn't always possible to do things at the optimum time, and I know from first hand experience that this isn't crucial.
Also, it is the intended use of the culms as well as follow up treatments of the material that is just as important.
For example, some uses, such as basketry making as well as some post-harvest procedures may require that the material contain moisture content during processing and treatment.

As such I believe other criteria, regardless of harvest time is the culms age, grading and selection of the materials best suited towards it's intended use, and having control of the drying, curing and any treatment processes.

I look forward to hearing of others experiences and opinions.

I guess it isnt the best for the clump to thin out shoots that have reached full culm size though, huh? As that is sort of a waste of energy?

Well, first we should examine the nature of the boo. Generally speaking, bamboo has a defined season, or grand period during which it's annual above ground growth cycle commences in which it produces the bulk amount of new shoots.
This limited window of opportunity makes it susceptible, should anything adversarial happen to these shoots. Under natural, wild conditions, the existing overhead growth, dead and alive, can be impediments to the shoots' survival by blocking vertical access or overhead sunlight to sustain the shoots needs.
Bamboo solves this dilemma by producing many more shoots than it can sustain, which also helps to keep away other competing species. Ultimately a percentage will survive, and culms which don't will eventually decompose and become food for future generations.

The problem, from our perspective, when harvesting from a wild or overgrown grove, is that a lesser percentage of culms harvested are of highest quality, and a much higher percentage of culms are of medium or lower grade. It is easy to roughly evaluate the culms during harvesting by checking how many branches the culm has, and if they had enough access to sunlight to produce lots of leaves. Compare an overcrowded culm with one that has had plenty of access to adequate sunlight and you will notice the difference.
This is not to say the lower quality culms are of no use - there are many uses for these.
What I'm suggesting is that a managed grove - one that has been thinned out enough to give each culm adequate sunlight and breathing space will produce a higher percentage of higher quality culms.
This doesn't mean that they have to be equally spaced from each other at the base - as in tree management, which spaces according to multi-decades of growing prior to harvesting.
With bamboo, 'rotating of the culms' is done under a 3-6+ year cycle, and location and emergence of new culms each year is not as easily predictable, though they will often surface in clusters or lines, according to the prevalence and viability of underground rhizomes.

Back to your question ... I see no harm in thinning out (smaller diameter) new shoots that have reached full culm size if it benefits other shoots and culms and their ability to have access to sunlight and space. ... even though optimally this is best done when they are small, as some species are edible at this stage ... or are easily decomposable.

Mark