Cultivation tool
Substrate calculator
Pick a species, set a target yield, see exactly what to buy and what to mix. Numbers are based on biological-efficiency ranges from published cultivation literature (Stamets, North Spore + Field & Forest grower data) — your actual results vary 20-40% based on cultivar, environment, and operator skill.
Inputs
Recipes are filtered to those documented for this species.
About this species
PoHu is the home-grow workhorse. Forgives substrate variability; produces reliably even when conditions are off-target. Best blue color at fruiting temps under 65°F; fades to grey-tan above 70°F.
Headline numbers
For 2.20 lb of fresh Blue Oyster (PoHu)
- Dry substrate
- 2.20 lb
- Hydrated substrate
- 5.51 lb
- 5-lb bags needed
- 2
Range: 1.70 lb — 2.76 lb
Hydrated to 60% moisture
1–2 bag range
Component breakdown · Master's Mix
50% supplemented hardwood sawdust + 50% soy hulls. Highest-yielding home-grow substrate for oysters, lion's mane, and king trumpet. Requires pressure-cook sterilization (90 min @ 15 PSI).
| Component | Dry mass | Hydrated |
|---|---|---|
| Hardwood sawdust pellets (oak/maple) | 1.10 lb | 6.89 lb |
| Soy hull pellets | 1.10 lb | 6.89 lb |
Spawn requirement
You'll need approximately 3.5 oz of grain spawn (10% of dry substrate mass). At typical retail $15-25/lb that's roughly $4 in purchased spawn — or grow your own from liquid culture (intermediate-tier curriculum).
Expected cycle
- Days to first flush
- 10–16
- Flush count
- 2–4
- Biological efficiency
- 80–130%
Heads-up
- Spawn requirement is meaningful. Either grow your own grain spawn (advanced-tier curriculum) or budget for purchased spawn at $15-25/lb.
How this works
The math behind the numbers
Biological efficiency (BE) is the cultivation industry's standard yield metric — fresh mushroom yield as a percentage of dry substrate mass. 100% BE means 1 lb of fresh mushrooms per 1 lb of dry substrate (before water is added), considered the baseline for healthy commercial production. Home growers typically hit the lower-mid range of the species-specific BE band; commercial farms tune to the upper end.
The calculation: target yield ÷ BE = required dry substrate mass. Then dry mass ÷ (1 - hydration target) = hydrated substrate weight. Component breakdowns are the dry mass × each component's fraction in the chosen recipe.
Why ranges: the "low / mid / high" estimates on each row reflect species BE variability. Plan around the high (worst-case) estimate; harvest the low (best-case) estimate when the cycle goes well.
Course path
Cultivation curriculum
Beginner → intermediate → advanced. Each tier covers the workflow this calculator's outputs feed into.
Reference
Strain library
Per-strain growth requirements, flavor profile, recipe pairings.
Supplies
Where to buy
Substrate components, spawn jars, bags, sterilization equipment.