What to track in a mushroom grow log (and why)
The point of a grow log isn't to fill in cells — it's to answer three questions later: which batches yielded best, which are running late, and what keeps contaminating? These columns are the minimum that let you answer all three. They're also exactly what the Mycro Grow Log records.
| Column | Why it earns its place |
|---|---|
| Batch ID / label | One row per block or bag so you can trace a result back to a specific grow. |
| Species & strain | Timelines and yields differ hugely by species — you can only benchmark like against like. |
| Substrate | Masters Mix, straw, supplemented sawdust — the biggest lever on yield and contamination. |
| Spawn type / ratio | Higher spawn ratios colonize faster; logging it explains why two blocks finished days apart. |
| Inoculation date | Day 0. Every "days in stage" and overdue flag is measured from here. |
| Dry substrate weight | The denominator for biological efficiency. Weigh it dry, before hydrating. |
| Colonized date | Marks the end of the spawn run — compare it to the typical range to catch a slow block. |
| Pinning / fruiting date | When you introduced fruiting conditions and pins appeared — tunes your timing next round. |
| Harvest date & fresh yield | The payoff. Log each flush; fresh weight (grams or lb) drives the BE calculation. |
| Biological efficiency (%) | Fresh yield ÷ dry substrate × 100 — the one number that tells you if a grow was good. |
| Contaminated? + cause/stage | Note green mold, bacteria, the stage it showed. Tallying causes is how you fix your loss rate. |
| Notes | Anything unusual — a temperature swing, a new supplier, a strain quirk. Future-you will want it. |
The one calculation people get wrong: biological efficiency
Biological efficiency (BE) is how you compare a good grow to a bad one on a level field. The formula:
Example: 1.2 kg of fresh oysters from a 1.5 kg dry block = 80% BE. Oysters often run 75–100%+, lion's mane ~50–75%, shiitake ~75–125%.
In a spreadsheet you add a formula column (=fresh_yield/dry_weight*100) and keep your
units consistent. It's easy to fumble — mixing grams and kilos, or forgetting to weigh the substrate
dry — which is the single most common reason a manual log gives numbers you can't trust. See the full
biological efficiency guide.
Spreadsheet template vs. an auto-calculating log
Both are valid. Here's the honest trade-off so you pick the right one for where you are:
| CSV / spreadsheet template | Mycro Grow Log | |
|---|---|---|
| Cost | Free | Free, no login |
| Biological efficiency | You write the formula | Calculated automatically |
| Days-in-stage / overdue flag | Manual date math | Automatic per batch |
| Contamination rate | You tally it | Tallied for you |
| Setup | Download & format | Open the page, add a batch |
| Best for | A few batches, full control | Anyone tired of the manual math |
The honest rule of thumb: start with the template if you like a spreadsheet and only have a handful of grows. Switch to a purpose-built log the moment you're re-typing the BE formula, eyeballing which blocks are overdue, or losing track of which cause is contaminating you — that's when the bookkeeping starts costing more time than it saves.
Skip the spreadsheet math — free Grow Log
Mycro's Grow Log uses the same columns as this template but does the work for you: log an inoculation and a harvest weight, and it calculates biological efficiency, counts the days in each stage, flags an overdue block, and tallies your contamination rate — no login, no limit, saved in your browser. Export back to CSV any time.
Try the free Grow Log → Become a Founding Grower — $99 →Free Grow Log — no login, no limit. Or lock in $99 lifetime founder pricing (fully refundable before launch).
General guidance from common cultivation practice, not guarantees — your numbers vary with strain, substrate, technique and conditions. Mycro is for legal culinary & medicinal mushrooms only.