I buzzed through the government documents for organic gardening real quick and didn't see anything. Call your county ag agent, maybe they can help. Billie

I don't think so, because cured concrete itself is quite stable/inert. And the few other things that are added to produce hypertufa (peat moss, perlite) are compatible with organic growing. It is only vermiculite that may be questionable, due to natural asbestos contamination from sources in the U.S.

And I'm sure you aren't likely to use contaminants that would affect your certification, like including stains or paints, or other chemical additives that the certification program might have issues with.

But since federal organizations are frequently whacked-out crazy, you'd best contact the certification people and get the final word from them.

Sue

I would think that because all ingredients come from the earth--are minerals, that organic cert. shouldn't be a problem. And that is why I dislike using poly fibers--been playing with various grades sizes of steel wool which I think in time will bleed red/rust into my pots, at least that is the hope. Something that changes over time.
Good luck on the cert. I will look for an update.
TB