Drake's answer covers why agar fails. The library adds how IMO1 is collected instead.
Diverse soil microbes are what IMO needs, and agar does not culture them (Office Hours Ep. 110, 12:32). Cho says to collect microorganisms in your own farming region (Cho, Recipe, p. 9).
- Fill a wooden box two-thirds full with hard-cooked rice (Cho, Theory, p. 51).
- Bury the box in leaf mould near the working field (Cho, Theory, p. 51).
- Cover it with a container box that lets air through, to keep animals out (Cho, Theory, p. 51).
- Leave it 7 to 10 days in spring and fall, or 4 to 5 days in summer (Cho, Recipe, p. 9).
You can work indoors in winter. Bring in a large volume of leaf litter with mycelium already growing, moisten it, and bury it in an indoor box (Office Hours Ep. 58, 26:40). That still needs leaf litter from outside.
The library does not cover collecting IMO1 from mushroom cultures grown at home.
