Prepare Grain Media
30 minutesSelect grain type, mix with correct water ratio, fill jars, and prepare sterilization run.
Field context
This workflow is part of 4 niche fields
Complete guide for spawn jar production — step-by-step workflow, tools, checklist, and expert tips to get started.
Select grain type, mix with correct water ratio, fill jars, and prepare sterilization run.
Calculate grain hydration percentage, jar fill volume, and pressure cooker sterilization duration.
Inoculate cooled sterile jars in HEPA flow or still air box using syringe or agar wedge.
Incubate jars at species-appropriate temperature, check for contamination, and assess colonization rate.
Calculate grain hydration ratio from dry grain and water volumes.
Verify supplement concentration in grain media if enriched.
Track incubation timeline and shake schedule intervals.
Calculate total grain volume for batch spawn production runs.
Key benchmarks for spawn jar production.
| Grain | Water % | Sterilize |
|---|---|---|
| Rye | 40-45% | 15 PSI 90 min |
| Milky | 35-40% | 15 PSI 90 min |
| BRF | 2:1 vol | 15 PSI 60 min |
A single unflamed needle or skipped ISO wipe causes contamination — technique matters more than equipment cost.
Breaking up colonized grain at 30% coverage doubles colonization speed for remaining substrate.
Purchase rye or millet in 50 lb bags from feed stores — fraction of mycology supplier prices.