← Moon Dog · Mushroom Cultivation Guides
Biological efficiency (BE)
Two growers can't compare yields just by pounds of mushrooms — a bigger block makes more mushrooms regardless of how well it ran. Biological efficiency (BE) normalizes for substrate size, so it's the figure cultivators actually use to judge a strain, a recipe, or a technique.
The formula
BE is fresh mushroom yield as a percentage of the dry substrate weight:
BE % = (Fresh mushroom weight ÷ Dry substrate weight) × 100
A BE of 100% means you harvested one pound of fresh mushrooms for every pound of dry substrate. Because fresh mushrooms are mostly water and the substrate is weighed dry, BE often exceeds 100% — that's expected, not a mistake.
The denominator is the substrate's dry weight (before hydration and supplementation water). Using the wet weight will make your BE look far worse than it is and ruin any comparison. If you only know the wet weight and moisture content, convert back to dry first.
Typical BE by species
| Species | Reasonable BE (first flush+) |
|---|---|
| Oyster (Pleurotus) | 75–150%+ |
| Shiitake | ~75–125% |
| Lion's mane | ~50–100% |
| Reishi | lower (slow, dense) |
These are ballpark figures across multiple flushes; a single first flush is lower. BE depends on strain, substrate recipe, supplementation, and how many flushes you count.
Why it's worth tracking
- Compare recipes — did adding bran actually raise yield, or just contamination risk?
- Spot decline — falling BE across batches can flag a tiring culture or a process drift.
- Plan production — once you know a strain's BE on your substrate, you can predict yield from block size.
Flush tracks BE flush by flush
Log dry substrate weight and each harvest and Flush computes BE automatically — across flushes and batches — alongside hydration, spawn-rate, and agar tools for 11 species. Free to download.
Sources
- Stamets, Growing Gourmet and Medicinal Mushrooms; Cotter, Organic Mushroom Farming and Mycoremediation
- Cornell Small Farms mushroom program (yield and BE conventions)
BE figures vary widely by strain and method; treat ranges as benchmarks, not targets.