Substrate Recipe Calculator
Pick a formulation and a batch size, and get the weight of every ingredient, the gypsum, the water to hydrate to field capacity, and whether the mix needs sterilizing or pasteurizing.
Choose your species first and the calculator suggests a recipe that suits its substrate. Gypsum is added on top of the dry base; water is calculated to reach the right moisture. Figures follow standard cultivator formulations — ratios vary by grower, so adjust to taste.
Your batch
Pick a species and we suggest a formulation from the database. Or choose a recipe directly.
Formulations are standard cultivator recipes; ratios vary by grower. Supplemented mixes must be sterilized (~15 psi), not just pasteurized — bran and soy hull feed contaminants as readily as mycelium. Species defaults come from the database (literature-range).
How to use it
- Pick your species. The calculator marks a recommended formulation (★) that matches the species' substrate and sets the target moisture.
- Choose a formulation. Confirm the suggestion or switch — Masters Mix, Masters Mix from pellets, supplemented hardwood sawdust, pasteurised straw, or straw plus bran.
- Set the batch size. Enter how much prepared (wet) substrate you want to make; presets cover common batch weights.
- Read the recipe. Each ingredient by weight, the gypsum, the water to add, and a treatment badge telling you to sterilize or pasteurize — with the reasoning.
Questions
What is Masters Mix?
A 50/50 blend of hardwood sawdust and soy hull by dry weight, hydrated to about 60%. It's high-yielding and the go-to for oyster and lion's mane — and because it's supplemented, it must be sterilized.
Do I need to sterilize or pasteurize?
Supplemented substrates — anything with bran or soy hull — must be sterilized at about 15 psi; the added nutrition feeds contaminants as readily as mycelium. Plain pasteurised straw only needs holding at 65–80 °C.
How much gypsum should I add?
Roughly 1% of the dry weight. Gypsum buffers pH, adds calcium, and keeps the mix from clumping.
What moisture should finished substrate be?
About 60% for sawdust mixes and up to 68% for straw. The squeeze test is the final check: a firm squeeze yields a few drops, not a stream.