Rye grain works well for absorbing fungal mycelium and is an inexpensive way to propagate a successful fungal colony. With a little preparation, you can grow almost any variety of mushroom on a bed of rye seed. While it is best to have access to laboratory sterilization equipment, you can do this at home with a few modifications and a watchful eye. Depending on the variety of mushroom you are propagating, you will see results in as little as one to two weeks.
There are two keys to successful mushroom growing on grains. You must thoroughly saturate the rye seed with the mycelium and you must prepare a moist casing layer consisting of one part peat, one part vermiculite and one part calcium carbonate. Rye seed can be in either the form of rye grass seed or rye berries. For a novice grower, small colonies of mushrooms can be grown in one-quart mason jars, moving to larger covered jars when you feel comfortable with the process. It is crucial to keep the environment of the jar warm and moist, as these are the natural conditions in which fungus thrives.
Begin by soaking your rye seed overnight to soften it. In the morning, drain it and place it into your mason jars. Add three quarters of a cup of water for every one cup of rye seed. Invert the lid on the mason jar before securing it loosely to prevent the buildup of undesirable fumes that will escape when you reopen it. The best way to sterilize the filled jars is in an autoclave, but if you do not have access to one, a pressure cooker works. It should be set at 15 psi for ninety minutes. The jars will need to cool completely before you add the mycelium. After the mycelium has been introduced to the rye substrate, mix it in by shaking the jar. For optimal growing conditions, keep the humidity levels around 65 percent outside the jar, 70 percent inside. Allow the jar to sit for five days and shake again.
The casing will be spread at a depth of one to two inches atop the rye substrate. The casing should be a mixture of one part peat, one part vermiculite and one part calcium carbonate. After you mix it, be sure to saturate it with water, allowing it to drain before you spread it atop the rye. After application to the rye, be sure to keep it moist by spraying it with water when it shows signs of drying out. Do not allow the rye to become wet. Store the jar in a warm place, free of drafts. Keep the lid loose to allow the proper exchange of gases. The growth rate will depend on the variety of mushroom you are growing, so be sure to research it prior to propagation.