How do I keep a mushroom grow log?

For each batch record the species, dry substrate weight, number of blocks and the inoculation date, then update the stage as it moves through colonization, fruiting and harvest. At harvest, log the total fresh weight so you can calculate biological efficiency. This free grow log does all of that in the browser and saves on your device.

How is biological efficiency calculated?

Biological efficiency (BE) is fresh mushroom yield divided by dry substrate weight, expressed as a percentage: BE = fresh yield ÷ dry substrate × 100. The grow log computes it automatically once you record a batch's harvest weight.

What is a good contamination rate for mushroom growing?

Many small farms run 5–15% contamination across blocks; under 5% is excellent and over 20% usually points to a sterilization, spawn or handling problem. Tracking which batches fail and at which stage is the fastest way to find the root cause.

Can I print labels for my mushroom blocks?

Yes. The free Mycro grow log prints a label card for every batch you are running: species, spawn date, the date it should finish colonising, block count and dry substrate weight, a write-in line for each flush, and a QR code that opens your grow log on a phone. Tape one label to each block or bag so the shelf always matches the log. No sign-up and no cost.

How long does mushroom colonization take?

Oyster mushrooms typically colonize a supplemented sawdust or straw block in 10–14 days; king oyster, lion's mane and chestnut in roughly 14–21 days; shiitake sawdust blocks can take 30–60 days. The grow log flags a batch that is sitting in colonization longer than typical for its species.

Free Mushroom Grow Log — track batches, stages & biological efficiency

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Active batches

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Blocks in production

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Avg biological efficiency

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Contamination rate

+ Add a batch

This log lives in this one browser (back it up once and it auto-syncs to a private link). Mycro is the full version: a real account you log into from any device, your BE and contamination patterns per strain and substrate rolled up over months, a harvest calendar, and COGS — so nothing is lost when a laptop dies or you grow past a spreadsheet. Join the early-access list:

Already know you want it? Become a Founding Grower — $99 once, lifetime founder pricing, and a direct line to shape what we build first. Fully refundable any time before launch.

How the grow log works

A grow log is just disciplined memory — but the value is in the numbers it lets you compute. Here's exactly what this tool tracks and how.

The five stages of a batch

Every batch moves through the same path. Tap the stage button on a batch to advance it; the log timestamps the move and shows how many days it has spent in each stage.

Stage	What it means	Typical duration
Inoculated	Spawn mixed into sterile substrate, just sealed.	Day 0
Colonizing	Mycelium running through the block in the dark.	Oyster 10–14d · King/Lion's Mane 14–21d · Shiitake 30–60d
Fruiting	Moved to fruiting conditions; pins forming, mushrooms growing.	7–14d to first flush
Harvested	Picked — record total fresh weight to lock in biological efficiency.	+ later flushes
Contaminated	Lost to green mold, bacteria or another contaminant.	Counts toward your loss rate

Biological efficiency (the number that matters)

When you record a harvest, the log computes biological efficiency = fresh yield ÷ dry substrate weight × 100%. Track it across batches and you learn the real BE for your strain, substrate and room — which is what tells you whether a project actually pays. See the biological efficiency guide for target ranges, and the Grow Calculator to plan a batch before you start it.

Overdue flags & contamination rate

If a batch sits in colonization longer than is typical for its species, the log flags it — usually the first sign of a slow strain or a hidden contaminant. Your contamination rate (lost batches ÷ finished batches) is tracked at the top, so you can tell whether a change to your process actually moved the needle. New to diagnosing contamination? Read the contamination ID & prevention guide.

Your data stays on your device — and auto-syncs once you back it up

This free log saves in your browser only — no account, no upload. Want a copy off this machine? Tap ☁ Back up once to get a private cloud link (opt-in — nothing leaves your browser until you do). After that, every change on this device syncs to that link automatically, so you can open your log on your phone or another computer and it's up to date. The paid Mycro app adds what a link can't: a real account you log into from any device (no link to keep track of), guaranteed long-term history across seasons, and multi-user access for a staffed farm.

Prefer a spreadsheet? Grab the free mushroom grow log template (CSV) — the same columns as this log, to fill in by hand. Or comparing tools? See Mycro vs MycoHub — an honest look at when a web-based grow log beats an offline phone app, and when it doesn't.

For legal culinary & medicinal mushroom cultivation only. Durations and ranges are general guidance from common practice, not guarantees.