How to label mushroom grow bags, jars and agar plates

Label every plate, jar and bag the day you inoculate it, with at least the species, the date and a short code that names its parent. GroCycle's cloning guide says to label new plates "with the species and inoculation date" (GroCycle), and Out-Grow calls a strain and a date "the whole system" for stored cultures (Out-Grow). Add a parent code, and a label can also tell you where a container came from.

What should you write on a mushroom label?

Write the species or strain, the inoculation date and a code that ties the container to its parent. That fits on a strip of tape and covers what you need at the bench:

• Species or strain: "Blue oyster" or your short code for it.
• Date inoculated: the day you added spawn, culture or a wedge.
• Code: one that carries the parent's code, so a jar's label points to the plate it came from. Our grow log guide explains the scheme we use, with codes such as LM-NS-1A1. Codes in our photos with a number in brackets, like CHE-NS(1), are our older way of writing the same scheme.

Bigger containers have room for more. A SARE-hosted oyster farm protocol records the straw weight, spawn weight, strain, date inoculated and pasteurization method on each bucket's label, then the harvest date and weight (Zumwalt Acres, via SARE). Anything that won't fit goes in your log under the same code.

Leave room for a word of warning too. A note like "exposed?" on the tape tells anyone at the shelf to check that jar before using it. Write down what you find when you check, the way the grow log's culture notes do.

Why do you label petri dishes on the bottom?

Label petri dishes on the bottom, the agar side, because the lids come off and get swapped. Microbe Online says to label "on the base (not the lid)", because swapping lids "changes which sample each result belongs to" (Microbe Online). An FDA lab sheet for schools says to write with a permanent marker "along the outer edges of the dish", so the label doesn't hide the colonies, and to keep dishes "upside down (label side up)" (FDA, via Ag in the Classroom).

Mushroom guides aren't unanimous: FreshCap's agar guide says to write the transfer number on the lid (FreshCap), and the notes on our own cover plate, transfer number included, are on the lid too. We'd follow the lab sources. North Spore's help center advises storing unused dishes upside down in the fridge (North Spore), and a plate kept that way shows a bottom label face up.

The same logic carries over to jars: lids get mixed up when you open several at once, so we put the label on the glass.

What labels survive a pressure cooker?

Autoclave tape that takes a marker is the safest choice for anything that goes through sterilization. The University of Michigan's autoclave procedure says to label bottles "by writing lab name and date on autoclave tape" (University of Michigan). Ted Pella's indicator tape "accepts writing with permanent markers" and withstands steam autoclaves (Ted Pella).

We couldn't find a test of plain masking tape, or of marker written straight on glass or a bag, through a pressure-cooker cycle. If you use them, label at inoculation, once the jars or bags have cooled; the inoculation date is the one to record anyway.

On filter-patch bags, keep the label off the patch: the filter "is for gas exchange" (Unicorn Bags).

Do labels matter for tracking generations?

Labels matter for generations because each transfer moves a culture further from its source. FreshCap says that with every transfer, the culture "takes another step away from the original and eventually will stop growing, or may develop a genetic mutation", and suggests you "keep track of the number of transfers" (FreshCap). Fungi Perfecti calls the first grain jars made from a petri dish G1 and advises no grain-to-grain transfers "beyond G3", because contamination "often can occur and not be detected until it is too late" (Fungi Perfecti).

A code that adds one letter or number per transfer counts your transfers for you. Vendors start G numbers in different places, so compare lines by that count, as our grow log guide explains. When a batch of jars goes green, the shared part of their codes points at the parent to check. And if you sell, you may be asked to prove your mushrooms were cultivated, not wild; our selling guide covers the spawn receipts to keep.

How do you print QR labels in Hypha?

In Hypha, our grow tracking app, open a block's More options menu and tap Label & QR, then Print label. Pick Small, Medium or Large (1½" wide, 0.6" to 1½" tall) and Hypha makes a PDF sized to the label, with the strain, the culture code, the start date and a QR code. To label a whole batch, long-press to select several blocks and choose Print labels from Batch actions.

Plates, slants, syringes, jars and bags are all blocks in Hypha, so each gets a label, and Hypha writes the parent's code into each child's code when you tap Transfer. Scan the QR with your phone's camera to open that block, with its notes and timeline. The link isn't public: it opens only for someone signed in to Hypha with access to that block. Labels and batch printing are on the free plan. Download Hypha.

FAQ

Can I reuse a jar with an old label on it?

Take the old label off first. A stale date or code on a jar you've refilled is worse than none, because it points to the wrong parent.

What date format should I use on a mushroom label?

Write the year first, in four digits, like 2026-10-31, and use that format on every label. A date like the 25-11-12 on our chestnut plate could be read more than one way; a four-digit year first can't. Hypha prints its labels with year-first dates.

How should I label cultures in the fridge?

Date every culture, because storage life varies. North Spore says plates keep up to 6 months and liquid cultures up to 2 months in the fridge, and that pink oyster cultures can't be refrigerated at all (North Spore).