What is Spawn?

Spawn is actual fungal (mushroom) mycelium (hypha/e) that has grown completely through a substrate such as sawdust. The mycelium has colonized the substrate: it looks white; it feels a bit spongy; it has a fresh scent.  This is a picture of spawn in the ‘Mushroom Cultivation’ section.

Spawn is prepared in autoclaveable bags with filter patches.  The sawdust and amendments such as gypsum or other minerals and grain are mixed, put in these bags, closed, and autoclaved to sterilize the substrate.  This is done with steam, under presser, in a large autoclave.  Once these bags are finished ‘cooking’ they are removed from the autoclave in a clean room where they are inoculated with mycelium in front of a HEPA filter.  This level of cleanliness is necessary to avoid large-scale contamination.  After the inoculation the bags are re-closed and left in a temperature & humidity & ventilation controlled environment to grow out. After several weeks the spawn is ready –  it looks white; it feels a bit spongy; it has a fresh scent.

At this point the spawn can be left to further mature and develop into grow blocks/kits or it can be used to inoculate other media/substrates.  When used to inoculate other substrates the spawn can be used loose, directly from the bag, or it can be formed/screened into plugs in plastic well sheets with styrofoam backing.  These little sawdust plugs are prepared in the spring and used as soon as possible to inoculate hardwood logs.  When using spawn to make sawdust spawn plugs,  fine sawdust, or wood flour, is used.  this fine grain sawdust can be screened into the plastic well sheets.  The sheets are then matured in an environmentally controlled are to allow the mycelium to regenerate inside each little well in the sheet.  As this process proceeds the mycelium again colonizes the sawdust substrate and each little plug is white, spongy, moist, fresh, and living.  Because spawn is actually a living organism, and because it can quite easily become contaminated and/or dry out and die, we prepare spawn for ‘just in time’ delivery in early spring – just in time for your inoculation.  It is shipped via Canada Post or UPS or Greyhound courier that takes several days.  Or it can be picked up at the farm (at our workshop for a 15% discount) or by arrangement, or spawn can be picked up at one of the farmers’ markets that we attend in Toronto.  Once it is received it should be stored properly and used promptly.  Spawn will last for up to 1 month but this will definitely compromise its vitality and your success.

Storage: in a clean, cool place in the clean bag that it arrives in.  If storing for more than 2 days open the bag up each day to allow ventilation because the spawn begins to ‘sweat’ and the plugs can get too wet.  This will lead to contamination.  Drying out will also lead to contamination as the spawn shrinks away from the sides of the well mold spores can enter.  Of course if the plug dries out completely it will die because it requires moisture for existence (like all life forms). Storing spawn at a cold temperature will slow down its growth and it should be allowed to come back to ambient temperature over several days before using.  Spawn should be used as promptly as possible.  Inoculation projects should be planned to get logs cut during the winter and stacked and ready for spring inoculation.  All tools such as:  drill;  bit; adaptor; or inoculator and wax should be on hand before the spawn arrives so that you are ready when it arrives.  You might  need to plan ahead for help with the inoculation if you are doing a large number of logs.

When you order spawn plugs they must be prepaid.  They will be shipped as soon as they are ready.  We begin shipping when the spawn is ready and we try to ship to customers in the order that they placed their orders.  If you need your spawn by a particular date you are well advised to order early.