simple answer: pasteurized straw has worked well for me.
longer answer consists of a few questions :)
- what species would you like to grow?
- which substrates are plentiful and cheap in your local area?
- do you have access to a kitchen (for hot-water pasteurization)?
- what quantity of mushrooms are you looking to grow, roughly speaking?
if you're in an urban area and want to grow oyster mushrooms (Pleurotus ostreatus) then 'used' coffee + cardboard would be my recommendation (this has the added bonus of not requiring pasteurization - since the coffee grounds are essentially pre-pasteurized).
if you're in a rural area then straw might be a better option. this will require pasteurization (either via heat or pH).
you might also consider hardwood logs as your substrate (depends on species, availability and time-scale).
@glyph thank you for the thoughtful responses! I live in a rural area in the Sierra Nevadas with access to plenty of wood/straw as well as coffee beans. I'm most interested in growing local varieties mostly to experiment with how fungus works. That being said, I'd also love to get to the point of growing oyster mushrooms or other useful mushrooms. I plan on starting with a shoebox size grow this year.
my pleasure! your focus on local varieties and experimentation is very refreshing (and much needed imo). the inaturalist website is a great resource for learning about species in your area.
straw will support many of the leaf-litter decomposers you might find in your local environment. you could try to establish wild-sourced mycelium in straw or you could cut the stem-butts off saprotrophic mushrooms and introduce those to the straw. observe and interact :)
@glyph this is perfect, thank you so much! As a bonus, here's the little volunteer who (along with Merlin Sheldrake's Entangled Life) helped reignite my interest in mycology.
Welcome to Grumpy's Bar! Twas once a proud bar for losers on Ravine Street, Cincinnati, now it is an online space for sharing triumphs, misdeeds, and musings over a digital Grumpy's Ale.