I have used standard 1" x 4" fir or pine lumber for building training boxes.
I have had a number of these in service for over five years and no problem
with them rotting away. I can detect some rot progressing on the inside
surface on some of them, but they are still good for a few more years.

One of the other guys in our club uses redwood for training boxes, and I
have used that as well. It will last longer than pine or fir. If you have
sealed your box with exterior varnish inside and out it should last for many
years.

Regards,
Roger Snipes
Spokane, WA. Zone 5-ish

----- Original Message -----
From: "Martin"

I've seen in several bonsai books and on the net the use of training boxes
for larger specimens of Yamadori etc. I was wondering what would be the
best
timber to use for say a 5 year stint as a training box. My main concern
being timber rot and it's effects on the roots of my plants.

I knocked up one box out of dressed (smooth sanded) pine planks I had
laying
around and sealed them with clear varnish but am still somewhat concerned
about the planks rotting.

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