material under raised beds
I'm continuing this subject under a new thread so that I can get some more feedback focused specifically on my concern. A link to the original thread (which includes photos of my garden) is at the bottom of this post.
When I first planned my veggie garden this season (we just bought the house last summer), I did not even know about concerns regarding the use of treated wood. I only learned about it after I had set my 4x4 posts in 36" of crushed gravel (I used gravel instead of concrete for a few reasons, one main reason being better drainage away from the post).
Once I started learning more, I decided that I would create raised beds out of untreated wood because I didn't want my veggies growing in soil that may have chemicals possibly leached into it from the treated posts. Furthermore, the previous owners of the home had landscapers do their yardwork so I don't know what treatments were put on the lawn over time.
After I constructed my bed frames and stapled landscape fabric to the undersides, I posted photos of my progress on this site. In response a lot of you have been telling me to use cardboard instead of the fabric, as this will not only improve my soil over time, but will allow my veggie roots to grow beyond the bottom of the raised beds. The only reason I used the fabric is, well, because a lot of Google hits for "building raised garden beds" instruct you to do so....so I did this thinking it was logical.
So right now my questions are:
1) Am I being too pedantic in thinking that the roots penetrating the native soil is not considered to be organic gardening, especially with the remote possibility of chemicals from the PT wood posts leaching into the soil and the possibility of residual chemicals in lawn treatments over the years.
2) How long will cardboard take to decompose to the point that roots can penetrate? I usually plan just after May 15th every year. Will it decompose enough by the time the roots grow to the bottom of the container?
3) What happens to my veggies (tomatoes, cukes, and herbs) if the roots can't penetrate the cardboard this season. Will they die or will their growth just be stunted?
4) How long do lawn treatments stay active in soil?
5) How thick of a layer of cardboard are we talking? I say Jon's photos and it looked like he had several layers.
Maybe I'm just being very overcautious, but I'd rather look silly and ask all these questions now, rather than after planting.
Thanks again, you're advice is very much appreciated!
Here is a link that might be useful: my original post