For some mushrooms, the acidity of the media, as measured by Ph, can influence growth. Acidity can be adjusted by adding 1 tbsp of ground limestone (CaCO3) to a gallon of water and using the latter to mix with the grain. Limestone may be purchased at a garden supply store (it's sometimes called "agricultural lime"). (the button or Portobello mushroom) is an example of a species that benefits from adding CaCO3 to the grain. For more information on the requirements of various species, consult a cultivation guide such as Paul Stamets' The Mushroom Cultivator (see "Sources" at the end of this article).
For the do-it-yourselfer, two methods of preparation for PDA are given below. The first is a method I have used with success; it is based on that described in The Mushroom Cultivator, by Paul Stamets and J.S. Chilton. The second is a method successfully taught and used by the MSSF cultivation group. Try one or the other, or both, on for size. You will soon either adopt one that suits you well, or you will more likely incorporate some of these jewels of wisdom into your own method, which will undoubtedly evolve over time. The procedures are similar to making a recipe from a cookbook.
|The Mushroom Cultivator|
He has written five books on mushroom cultivation, use and identification; his books Growing Gourmet and Medicinal Mushrooms and The Mushroom Cultivator (coauthor) have long been hailed as the definitive texts of mushroom cultivation. Other works by Paul Stamets include Psilocybe Mushrooms and Their Allies (out of print), Psilocybin Mushrooms of the World, MycoMedicinals: an Informational Treatise on Mushrooms, and many articles and scholarly papers.
At this point, if you haven't done so already, I recommend that you invest in a good cultivation guide such as The Mushroom Cultivator by Paul Stamets and J.S. Chilton (see "Sources"). You may also wish to order some cultures via mail from suppliers such as Fungi Perfecti or Western Biologicals (again, see "Sources") and those cultures will come with specific instructions. Of course, when you are comfortable with the techniques, you may also begin to experiment with varieties collected from your local area or grocery by taking tissue cultures or even by advancing to spore cultures.