New — track where a batch came from. The free Culture Library logs your sources, petri dishes, liquid cultures and grain spawn, so a block traces back to the jar, the plate and the supplier it came from — and a contamination traces forward to everything it touched.
New — delivery labels and an address book. Keep your buyers and suppliers in 📦 Deliveries, log what weight went to whom, and print the label that goes on the box: buyer, address, species, weight, batch number and your own contact number — plus a QR the buyer can scan to call you, or to text you about that exact batch. Because the batch number is on it, a question about a delivery still leads back to the block, the jar and the source.
New — what a pound actually costs you. Put what a run cost — substrate, spawn, supplies, labour — on its card with the 💵 Costs button, and the log works out your cost per pound, grouped by method and by strain. Failed runs are counted, because they cost real money and produced nothing. Add what you sell for and you get margin per pound too — so a test run tells you something financial, not just that it worked.
+ Add a batch
Already know you want it? Become a Founding Grower — $99 once, and your sign-in account opens straight away: the same log on the laptop and the phone, no link to keep track of. Lifetime founder pricing, and a direct line to shape what we build first. Fully refundable any time.
Is Mycro a mushroom growing app?
Yes, and it is a web app rather than a download. Mycro's grow log is mushroom growing software that opens in any phone or laptop browser: there is no iOS or Android app to install, no account to create and no free-trial limit on how many batches you track. Your log saves on the device you are using, and you can back it up to a private link that opens on any other device.
What does mushroom grow log software actually do?
Good grow-log software does the arithmetic a notebook cannot. It should compute biological efficiency from your dry substrate weight and fresh yield, count how many days a batch has spent in each stage so a slow block stands out, work out your contamination rate, and total what a run cost you so you can see the real cost per pound. Mycro does all four automatically as you log batches.
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.
What is actually costing you blocks
A rate says how often you lose a run. It never says why, and green mould on grain, a bacterial wet spot and cobweb in the fruiting room are three different problems with three different fixes. When you mark a run contaminated the log asks what went wrong, using the same names as the contamination guide, and quietly keeps the stage the run was in before the mark overwrites it. Your losses are then grouped by cause and ranked by the blocks they took, not the number of runs, with what those runs had cost you. A loss you could not identify still counts as a loss and attributes nothing — and while there are as many unidentified losses as identified ones, the log says the ranking cannot be trusted yet rather than naming a culprit.
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.
Frequently asked questions
Why track the cause of a mushroom contamination, not just the rate?
A contamination rate tells you how often you lose a run; it never tells you what to change. Green mould on grain, a bacterial wet spot in a block and cobweb in the fruiting room have three different fixes, so a single percentage groups together problems that have nothing to do with each other. Record what went wrong and which stage the run was in when it went, and the same losses turn into a shortlist: this mould took this many blocks, at this point in the grow, and cost this much. The free Mycro grow log asks for the cause when you mark a run contaminated, keeps the stage it was in before the mark overwrites it, and ranks your losses by the blocks they took. Losses you could not identify stay in the total and are counted separately, because a guessed cause is worse than a gap.
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 do I work out my cost per pound of mushrooms?
Add up what a run cost you — substrate, spawn, supplies and bags, and your labour — then divide by the fresh weight that run actually harvested. Cost per pound = total run cost ÷ fresh yield. Count your failed runs too: a contaminated batch cost real money and produced nothing, so leaving it out flatters the number. The free Mycro grow log does this per batch and then groups it by method and by strain, so you can see which recipe genuinely produces the cheapest pound rather than which one has the cheapest substrate.
What should go on a mushroom delivery label?
A delivery label for fresh mushrooms should carry the buyer's name, the delivery address, the species, the weight in the box, your batch or lot number, and a contact number the buyer can reach you on. The batch number is the part growers most often leave off, and it is the one that matters: if a buyer calls about a delivery, the batch number is what lets you trace it back to the block, the spawn jar and the culture it came from. The free Mycro grow log prints all six on a label from a delivery you log, and adds a QR code the buyer can scan to call you or to text you about that batch.
How do I keep track of who I sold mushrooms to?
Keep an address book of buyers and suppliers, and record each delivery against the batch it came out of — date, buyer, weight. That gives you two things a sales spreadsheet does not: you can see how much of a harvest has actually gone out and how much is still on the shelf, and if a buyer reports a problem you can trace that exact delivery back to the batch and its culture. The free Mycro grow log does this in the browser with no sign-up, and exports the deliveries to CSV.
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.
For legal culinary & medicinal mushroom cultivation only. Durations and ranges are general guidance from common practice, not guarantees.