Just found your post. The gardening forum is not very active. Oh well.
I try to do organic gardening. I will have to look up this Rudolph Steiner.
I am not sure that I know exactly what biodynamic gardening is, but Ian Jones on The Miracle Gardener- 3ABN (now off the air) stated that this was his method of gardening. I tried to use his double digging method this year, but I also built raised beds - I have 8 beds that are 3' x 8' and several other beds that are 2' x 8'. They are 3 landscape timbers high. I had to use the treated timbers, as that was all I had access to. And I needed the raised beds for various reasons. I did buy topsoil, peat moss, sand, Epsom Salts , etc. because I only live on 1/5 of an acre. I used lots and lots of leaves from the neighborhood that my nice neighbors bagged up for me when they cleaned their yards this past fall.
And I used lots of earthworm castings from my compost pile.
I bought most of my seeds from Johnny's Seed Co., but not all of them did very well, so I have had to buy some from Lowe's/Home Depot, etc.
I am trying to do the square foot gardening, as I understand it, by planting things pretty close together - little room for weeds, etc.
I also recently put extra Epsom Salts everywhere because there was some yellowing of various leaves. It worked wonders. We have had a little rain, and the plants have taken off in 1-2 days. Of course, I also side dressed with some compost.