Buying oyster mushroom spawn: types and storage

What oyster mushroom spawn is

Spawn is the starting material you add to a growing medium. It is living mycelium, the root-like network of a mushroom, growing on a carrier such as grain.

North Spore, a US seller, puts it this way: "mushroom spawn is already alive so care must be taken in storing and handling it." ¹

An Australian seller, Rootlab, describes its pink oyster product like this. "Grain-spawn mycelium, Gourmet and medicinal strains are available fully colonised for mushroom cultivation." ⁵ This page is only about culinary mushrooms, so ignore the medicinal part of that line. Mushrooms that appear on their own in a lawn are a separate matter, and why lawn mushrooms shouldn't be eaten is explained on its own page.

Spawn is not the same as a grow kit. Our page on mushroom grow kits in Australia covers kits, and spawn is for when you want to mix your own substrate.

Grain, sawdust or plug spawn

Sellers offer spawn on different carriers. North Spore describes three.

Plug spawn: "They are locally produced wooden dowels that we've grown mushroom mycelium on." You need "freshly cut hardwood logs" to use it. ²

Sawdust spawn: it is "Used much like plug spawn but requires an inoculation tool for injecting into logs." ²

Grain spawn: "Grain spawn is not suitable for inoculating outdoor logs and is meant for indoor cultivators or inoculating straw beds." ²

North Spore also says grain spawn "has a few applications for outdoor growing, too!" and adds "We recommend sticking to oyster species for these applications" ¹. Spawn doesn't suit every outdoor job, so check the species first.

If you have logs, read the seller's notes on which species suit logs first.

What an Australian listing looks like

On 26 October 2026 we looked at Rootlab's pink oyster grain spawn page. Prices are in Australian dollars. The page shows "Price range: $18.00 through $50.00 inc. GST", with options of 100gms, 300gms, 1Kg and 2Kg. ⁵

The seller's directions are short: "Add at least 5-20% grain spawn in your substrate." ⁵ The substrate is the material the mushrooms grow on, such as straw.

The same page gives a warning: "grain spawn do not come with instructions. This is a advanced product." ⁵

That is one seller and one species, so it's a sample, not a market survey. Prices change. Check the seller's page for today's figure.

How long does oyster mushroom spawn keep?

It depends on the type, the species and how you store it. Here is what two sellers say.

For grain spawn, North Spore says "Grain spawn can be stored for up to 3 months in the refrigerator." ³

For plug and sawdust spawn, a different North Spore page says they "will store for six months to a year in a refrigerator." ⁴

Pink oyster is different. North Spore says "Pink oyster spawn is not cold-tolerant and cannot be refrigerated." It adds "Store at room temperature for up to 1 month." ³

That page also says "The fresher the better, but mycelium is pretty resilient." ⁴

These are one US seller's figures for its own products. Another seller may give different ones, so follow the instructions that come with your spawn.

Opened bags

Plan to use all of a bag once you open it. North Spore says "Attempting to store it after opening will most likely result in contamination." ³

Contamination means unwanted moulds or bacteria have got into the spawn.

Buy a size that matches your substrate. North Spore says "One 6 lb. bag of grain will inoculate 120–165 lb. of sterilized sawdust, or 100–130 lb. of pasteurized straw." ³ That is for its own product, so check your seller's ratio.

Check shipping before you order

Check shipping to your state before you order. As one example, Rootlab's page says "We can ship to Western Australia except for Wood ear, Reishi, and Lion's Mane." It adds "The list of permitted species for WA is regularly updated." ⁵

That is one seller's statement on one product page. Ask the seller if you live in another state or are unsure.

Spawn that sits in a hot post van is a worry too. North Spore says "We recommend insulated shippers when daytime temperatures in your area are above 80°F." ³

Questions to ask before you buy

- Is it grain, sawdust or plug spawn, and which species is it? - How long does the seller say it keeps, and does it go in the fridge? - Is the price in Australian dollars, and does it include GST? - How much substrate does one bag cover? - Will the seller post to your state? - Does it come with instructions? Rootlab says its grain spawn doesn't. ⁵