Curing Bamboo??

[Precog]

Hi Everyone,

Down at our local community garden we have a magnificient 5 year clumping stand of bamboo that we want to use for a few building projects (e.g. pergola).

Im wondering if anyone knows when is the best time to harvest bamboo and any techniques on curing it prior to use?

Have a great day!

Precog

[ho-hum]

Hello Precog


Have fun with the bamboo.

Winter or dormant season is the best time to cut bamboo but you can drop it at any time.

When cutting I like to cut and drop the bamboo and leave it in the sun for a week or so. This is to get the bamboo to pump as much water, sugars, starches etc into the leaves and branches. It is then carted home. Do not trim the length too much.

Like any wood it needs to be dried and cured. A friend of mine got excited about bamboo and dried some in the sun for 3 months to build a shadehouse. It looked excellent too and then every piece started to shoot and grow. He had to remove all plants and kill the bamboo with round-up.

I made the bamboo straight by wrapping number 8 wire fairly tight around the middle. On both ends I ran a loop of wire around and then twitched it tight with an iron bar. I re-tightened this twice. On the 'big' end I had to run another loop round after about 6 weeks as the first one was threating to snap. It took the best part of 12 months to cure properly. It sat up on 3 44gall drums. They were at this stage 6m lengths which were turned a few times.

We cut wild bamboo [in the Northern Territory] with an electric chainsaw. Also you will make a hell of a mess with the clump though, the best bamboo is in the middle so the clump wont look great when you are done. The bamboo was split with a banana knife and mallet to start and then the knife jammed in a frame and dragged thru with the Landcruiser.

I did split one spare piece after about 6 months and finished up drying it over a barbecue fire. It was cut up and used to face a gate and teck-screwed on.

Hope this helps,

Cheers

Floot

[Richard on Maui]

As Floot says, the best time to harvest bamboo poles for timber is in the dry season, when the culms are least full of water, sugars and starches. If you want to get really hardcore, you will do it on the phase of the moon when the moisture is being sucked into the earth, (when is that, full? never been much of one for planting with the moon)...
Floot's theory of the best poles being in the middle might be true for a wild clump, but in a well managed clump you will have culms of the right aged spaced evenly around.
Just as critical as harvesting poles at the right time of year is getting the ones of the right age. At about 3-4 years in most species the poles are mature, and any older than 5 years and they are probably getting weak as they return most of their energy back into the clump. There are various signs of age, such as the amount of leaves at the top (mature poles usually are somewhat less bushy and green than the youngsters), the pole itself will often be yellowing a little from the sun (if it is getting enough sun) and there are things like "culm sheaths" the leaves that are adapted to protected the emerging branches - some species have "persistent culm sheaths" but most will show less culm sheaths on the older poles. Another clue is the amount of aerial or adventitious roots. All these things vary depending on the species.
So, if your clump has been in the ground for 5 years precog, you are probably just starting to see poles that will do what the clump is capable of in terms of height and diameter. PLEASE DO NOT CUT THE BIGGEST POLES IN YOUR CLUMP THIS YEAR!
If you do that you will set your plant back by several years. What you want to do is thin out the oldest culms, which are going to be the smallest. Right?
All things being equal, with a happy young bamboo plant, each progessive year you will get consistently bigger poles until most of each years shoots will be around the same height and diameter as the rest in the clump... I realise that if you don't already know what I mean, this probably makes no sense!
So, if I understand you correctly, and your plant is 5 years in the ground, the poles that came up this year, which should be the biggest and the fattest, will be ready to harvest in about 2008/9...
If I misinterpreted what you said, and your poles are actually 5 years old, well, cool, you have some bamboo ready to harvest for timber. You can still use the immature stuff, that is the undersized material, for various things...
So, once harvested, I would actually recomend drying your poles in the shade as they are less likely to crack or split. If you have to dry them in the sun, you need to rotate them every so often so that they get even amount of shade or they will dry unevenly, and the side that dries more quickly will split...
Floot's suggestion to dry it with the leaves on makes good sense. You can sometimes prop the culms up inside the clump they come from. This gives the necessary shade, and facilitates moisture removal as the leaves will continue to transevaporate even after the culm has been severed from its roots. After 2 or 3 weeks, I would cut the tops off and transport the poles to my longterm curing shed or wherever. Wipe them down to remove any mould or whatever and stand them upright if possible for another 6 months or whatever. I'm yet to have access to much bamboo of the right age and quality to have bothered with the full curing trip...
Some people put the base of the culm in a bucket full of a chemical solution such a borax, so that the chemical is sucked up and replaces the starch and makes the pole unattractive to boring insects. Same sort of theory is at play in immersing poles in a running stream or in tidal saltwater, although this would obviously be easier to do horizontally than vertically!
A real good book on the subject is Victor Cusak's Bamboo World, and Bamboo Rediscovered. I think I have those titles correct. Probably available from your local library, if indeed your local library hasn't sold all the books and replaced them with computers that will wear out in 5 years.

[Precog]

Thanks for the detailed reply. Yes ... the bamboo clump was planted 5 years ago so the intial poles in the middle of the clump would be about 5 years old. The bamboo is called 'old hamii' or something that sounds like that and it is dead straight, 10-12m tall.

From what your have said, I could cut the some poles from the middle that are around 4-5 years, leave it in situ for 2-3 weeks and then moving it to a curing shed. I presume by shed you mean it has to be in a sheltered area away from the rain??? Could I sit it outside under a makeshift tarp horizontally just off the ground instead??

Thanks for your help

Have a great weekend!

[Richard on Maui]

Ah, Bambusa oldhamii. Yeah, quite an erect species. That one can get up to 60 feet I think, so depending on your climate your bamboo will probably get a bit bigger in the next few years... The material at the middle of the clump would tend to be smaller than the maximum, both in height and diameter, right?
You could lay it down horizontally, but I don't know, you'd want to rotate it a little bit as I said, and probably ensure a good airflow around it. As your end use is a pergola, maybe it isn't so important to keep it out of the rain while it cures? Got any good shade trees you can lean the poles against? Of course, bamboo exposed to the elements, cured or not, is going to have a limited lifespan. But that's okay, because every year you can harvest four or five new poles from each plant, and making stuff out of it is good fun.

[Veggie Boy]

So I wonder how this went. Was the pegola built

[maimai]

Thanks Precog for your question.And thanks Richard on Maui and Ho-hum for your answer.I like this forum very much! I can learn more thing I didnt know.I'm a woman

[Veggie Boy]

A woman and a spammer