Mycelial culture in Petri dish
 

Generating your own spawn is by far the cheapest way of inoculating mushroom beds, blocks, bags and logs.  Detailed instructions can be found in Paul Stamets books "The mushroom cultivator" and "Growing gourmet and medicinal mushrooms".  To inoculate spawn, wedges of agar are transferred to the jars or bags containing sterilised substrate (i.e. rye grain).  Organic rye grain is the best substrate for making spawn masters, although some people prefer using millet which has smaller seeds.  The initial spawn run takes about 2 weeks from inoculaton, and the jars/containers should be shaken weekly to break up and spread mycelium.  The grain spawn masters can then be used to inoculate more grain spawn or sawdust spawn, or the final bulk fruiting subtrate.

Compost or woodchip based beds are suitable for Agaricus bisporus, Wood Blewit, King Stropharia or Morel mushrooms.    Beds should be prepared outdoors, during spring for autumn fruiting the same year, preferably in a shady location with plenty of rainfall.  Pits around 12-18 inches deep are dug, and lined with a layer of horticultural grit, for drainage. The substrate consists of composted straw/manure for Agaricus or Wood Blewits, or woodchips/manure for King Stropharia or Morels.  Substrate should be mixed with the spawn, or laid down in alternate layers of substrate/spawn. A peat/lime based casing layer of 2-3 inches should be layered on top of the beds and watered every few weeks.   Similar beds may be prepared indoors i.e. in a garden shed, inside wooden frames.