Russell D. wrote:
I just got off the phone with a very helpful young man at my local Home
Depot. I was gathering info from him on the prices of redwood, cedar and
composite planking that I want to make grow boxes from. When I mentioned
to him that I was going to make grow boxes he suggested that I use
treated lumber, quickly adding, as if he anticipated my protest, there
is no longer any arsenic used in the treating process and nothing is
used that would be harmful.

Personally, I would NOT use treated lumber for boxes where I will grow
edibles. While use of CCA (Copper Chromium Arsenate) is basically
banned in the USA, that doesn't mean there are no health risks
associated with lumber treated with other products. Remember, the other
treatments also involve poisons, like copper. You might find this USDA
publication useful:

http://www.fpl.fs.fed.us/research-ar...723/index.html

In particular, click on the link in the upper right for the FAQs. At
the bottom there are a bunch of other links. I found the one on the
alternative types of treated wood interesting.

--
Henry