Using straw as a mushroom substrate works well for some mushroom varieties. Oyster and paddy straw mushrooms come to mind. This mushroom substrate recipe is easy to follow and inexpensive.
It is one of the easiest and cheapest mushroom substrate recipes to fruit mushrooms on.
Straw can be messy to prepare so I suggest doing this outdoors if possible.
Cut the straw into 3″ or 4″ pieces. You can use scissors or put it into a garbage can and use your weed eater to chop it up.
If you use the weed eater method I recommend wearing goggles and a mask. It flies around pretty good.
Straw needs to be sterilized just like any other substrate. This can be done with a pressure cooker, or with lime water.
The pressure cooker method is the same as for any other substrate. Wet thoroughly then pack tightly in a bag and cook for 90 minutes at 15psi.
Let cool completely before mixing in grain spawn.
Here is the recipe for lime water.
To 2 gallons of water add 34 ml (2 1/3 TBSP) hydrated lime, soak straw for 2 – 4 hours.
The straw must be squeezed out after it is limed. Some people place the straw on a screen and let it drip out. I just hand squeeze it till nothing but a drop or two of water comes out.
WEAR GLOVES. Lime water is caustic to your skin.
Pack it down into the bag tightly. The grain and straw need to be in close contact for colonization.
Seal it and let it set in a dry dark place for a few weeks.
Straw seems to colonize faster than sawdust. Mine usually takes about 4 – 6 weeks and they are ready to fruit.
I have been using this recipe for over two years now with only one instance of contamination. This is my go-to medium for growing oyster mushrooms.