Question
hi, just wondering about your answer to a previous question about concrete and organic gardens.

1). is there any toxic effect (or soil measurement) from eating vegetables grown within a raised bed made from large rocks and mason mix?

2). would the vegetables still be considered organic or healthy even if grown in a total concrete block raised bed?

3).what is an example of a non-toxic concrete sealer that you advised for less water absorption?

Answer
I don't think there is any problem with using cement or rocks.  We use a mixture of Portland cement (chemically it is a mixture of (Dicalcic and Tricalcic Silicate, Tricalcium Aluminate, limestone, shale, and gypsum), mixed with a cement sand in a three to one ratio.

The only effect we have noticed over 16 years is that along the edges, water is absorbed, and the soil is not as moist as it is in the center of the bed. In the testing of our soil for organic certification, nothing was found to be contaiminated in any way.

You could use Natural cement: which has only Dicalcic Silicate (Belite). It is produced from argillaceous limestone and called Rosendale Natural Cement, available from Edison Coatings, Inc. at 3 Northwest Drive, Plainville, CT 06062, Phone: (860) 747-2220 or (800) 697-8055
http://www.rosendalecement.net/html/rosendale_cement_chemistry.html

We have never used a concrete sealer, but we have stained concrete with organic soil additives that give a yellow stain.

http://www.youtube.com/watch?v=-I4ibS9w7oU&feature=plcp&context=C480cb2dVDvjVQa1

We just built an entire garden our of cement and gravel for raised beds....you can watch it at the above link....and everything is thriving in the garden.

If you have any other concerns, please write again.