[Greenbuilding] (Greenbuilding) Wood Info

[Chris Green]

Khalil Hassan wrote:
> I am looking for wood that will in contact with the ground and will be 
> used in an organic gardening application(raised beds and base boards 
> for a cold frame.  Any suggestions for a wood type or alternatives 
> would be appreciated.
>
> I've checked a couple of garden listservs but "thinking green" is 
> generally absent from them.
>
> Khalil
>   
Besides cedar and redwood, already mentioned, some of the top rot-proof 
native woods on this continent are various oaks, bald cypress, black 
locust, and osage orange--sometimes also called 'bo-dark' from 'bois 
d'arc."

Black locust. Probably the best of a tough lot. In tests of fence posts 
in Missouri, untreated locust posts were pulled out of the test plot 
after 23 years showing little sign of decay. They only pulled the posts 
out because they (agricultural scientists) needed the plot for other 
research, so the posts could have lasted much longer.Being warm and 
humid, I suspect Missouri soil would normally eat any wood put into it 
in a few years.

Black locust has gone feral in my home town in the deserty part of 
South-central British Columbia in the past few decades- so they're quite 
hardy, and easy to grow, if you want to do that. The tree should be 
quite mature before the wood is too rotten to use.

Osage orange can be a weed in parts of Texas, IIRC, and is approximately 
as rot-resistant as the others mentioned. However, it can be difficult 
to find a supplier.

Two other highly resistant woods are hickory and Northern Catalpa. I 
know from experience that catalpa grows quite fast, so is also a good 
choice.
Reference at a Forest Products Laboratory page:
http://www.fpl.fs.fed.us/rwu4723/preservation_faqs/durable.html

Perhaps look for an 'urban forestry' company, or a local tree removal 
service which harvests logs from inside the cities and tries to find 
uses for the wood? In Southern California, perhaps one can get wood 
salvaged from the trees cut down after the forest fires.

For reference purposes, one such company is: 
http://www.urbantreesalvage.com/lumber.html
I know nothing about this company so I can't endorse them, but their 
website is interesting. There should be companies like this in 
California--there are  several in Florida where hurricanes knock down a 
lot of trees...

I don't know if the following idea is appropriate for your application, 
but here's a real old pioneer trick from my area: you can extend the 
durability of wood in contact with the soil by charring the wood so that 
about 1/4"- 1/2" of the outside  is turned into charcoal. This can be 
done with a tiger torch or, since Hallowe'en is approaching, a bonfire 
(where permitted).
In 1928, a  friend of mine's father was clearing his homestead for 
farming and charred some split fir fence posts in a big bonfire, then 
built a fence with the posts. The fence were still standing in the 
1970's and '80's, and may still be there...The science behind this is 
that the charcoal isn't eaten by any known insect or bacteria, and may 
even kill them. So the wood takes a long time to rot.

I have a hunch that the charcoal may also absorb borax in a water 
solution and so fight off decay even longer, but I have no way of 
proving this at this time. Unfortunately, borax or other boron wood 
preservatives are soon leached out of ordinary solid wood by water. 
Don't know if this happens to charred wood....

Rubbing up against the charred wood tends to make one's clothes dirty, 
which may also be something to take into consideration.

Cheers,

Chris Green.