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My incubation chamber is heated by a mat at the bottom should the mat temperature be 26 or the overall temperature within the incubator?
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Home / Mushroom Cultivation / Mushroom Grow Kits / SpawnTubs
Sterile grain spawn
Sterile grain spawn
SpawnTubs
Sterile organic rye grain spawn, ready for you to inoculate. Inject your own gourmet culture, let it colonise, then expand it into your own bulk substrate. Sold singly or as a set of three.
★★★★★ 5.0 · 29 reviews Price range: £18.00 through £45.00
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For cultivating legal gourmet mushroom species only. A gourmet liquid culture or spore syringe is not included.
Made in the UK
organic rye, sterilised fresh to order
organic rye, sterilised fresh to order
Sterile guarantee
arrives sterile or we replace it
arrives sterile or we replace it
You inoculate it
any gourmet species, your choice
any gourmet species, your choice
20 years of spawn
grain spawn is what we know best
grain spawn is what we know best
DifficultyIntermediate, you inject and expand
Time to harvestSpawn stage, not a finished kit
YieldSpawns a batch many times its size
GrowsGourmet species, your choice
The short version
A tub of sterile organic rye grain, ready to inoculate. You inject 3 to 4ml of your own gourmet culture through the self-healing port, shake it through, and let the grain colonise. Once it is solid white you have living spawn, which you mix into your own bulk substrate to start a far bigger grow. It can also be fruited on its own. Sold as one tub or a set of three.
How it works
How SpawnTubs work
A SpawnTub is the living starter for a grow, not a finished kit. You inoculate sterile grain, let the mycelium take it over, then expand that colonised grain into a much larger batch of bulk substrate of your own. One small tub becomes the engine for a far bigger grow.
1
Inoculate the grain
Wipe the lid with the chlorhexidine wipe, fit the sterile needle, and inject 3 to 4ml of your own gourmet culture or spore solution through the self-healing port. The port reseals the instant the needle comes out, so the grain stays protected. Work somewhere clean and draught-free.
2
Shake to spread it
Give the tub a good shake to scatter the solution right through the rye grain. The tub is filled to about two thirds on purpose, so there is room for the grains to move and the inoculation to reach the whole batch.
3
Colonise the grain
Set the tub somewhere steady, aiming for around 24 degrees, though anywhere from 18 to 24 is fine as long as it holds. Skip the heat mat and watch for condensation. Do not pull off the pink filter, it is what lets clean air in. Leave it be while the white mycelium spreads across the grain.
4
One shake at 60 to 70 percent
When the grain is roughly 60 to 70 percent colonised, shake the tub once more to break up the lumps and spread the mycelium around, which speeds the rest of the run along. Do this only once, and gently. Shake too hard or too often and you can stall it by not giving the mycelium a chance to grab hold again.
5
Expand into bulk
Once the grain is solid white, you have a tub of fully colonised spawn. Mix it into your own pasteurised bulk substrate (coir, hardwood or manure, depending on your species), top with a thin casing, and let the mycelium run through that before you fruit it. Each tub spawns a batch many times its own size.
It can also be a substrate. If you would rather keep it simple, a SpawnTub can be fruited as it is, straight from the grain, instead of being expanded into bulk. The two-step grain-to-bulk route gives a bigger harvest, but the grain on its own will fruit too.
Why this one
What makes a SpawnTub different
Most of our kits hand you the spawn and the substrate together in one box. A SpawnTub is just the spawn, on its own, so you choose how far you take it. That makes it the most flexible thing we sell.
A SpawnTubA complete grow kit
What it isSterile grain spawn, the living starterSpawn plus substrate, ready to fruit
SubstrateYou supply your own, any amountIncluded and fixed in size
ScaleSpawns a batch many times its sizeWhatever the box holds
What you learnGrain spawn and grain-to-bulk expansionThe full grow start to finish
Best forGrowers running their own bulk substrateA first grow with everything in one box
Buy a single tub to learn the spawn stage, or a set of three to inoculate with different species at once, or to keep clean spawn going across several grows.
Why it works
How we make it sterile
Grain is rich and warm and microbes love it, so the spawn is the one thing that has to be perfectly clean before you inoculate it. With over twenty years of making grain spawn behind us, this is how we get it there.
Autoclaved
Each tub of organic rye is sterilised at 15 PSI in an electric autoclave, which is what it takes to make grain this rich clean enough to inoculate.
Cleanroom processed
It is then processed inside an ISO Class 5 cleanroom, and we tape around the rim of every lid afterwards under laminar flow for extra contamination resistance.
Gypsum added
The rye is dressed with gypsum, which keeps the grains from clumping so they shake apart cleanly and colonise evenly.
Worth noting
No process is ever perfect, which is exactly why every tub is backed by the Sterile Guarantee further down.
In the box
What's included
Sold as a single tub or a set of three. Each tub is complete bar the culture, which you add yourself.
Each SpawnTub
Needs 3 to 4ml of culture
- 400 to 450g (a quart jar's worth) of sterilised organic rye grain with added gypsum
- Filled to about two thirds for shaking and grain-to-grain transfers
- HEPA-filtered air exchange (the pink filter)
- Self-healing rubber inject-thru port in the lid
- Sterile needle
- Chlorhexidine alcohol wipe
Quantity options
You add the culture
- 1 tub, for a single grow or to learn the spawn stage
- 3 tubs, to run several species or several grows at once
- Each tub colonises and expands independently
- Bulk substrate is not included, you supply your own
The one thing you add
What you'll need
The culture is not included.
A SpawnTub is sterile and ready to inoculate, so you supply the living part: a gourmet liquid culture or spore syringe, 3 to 4ml per tub. You will also need your own bulk substrate to expand the colonised grain into, unless you fruit the grain on its own. We make gourmet liquid cultures you can inoculate it with.
Liquid culture has known, predictable genetics and can be incubated a little warmer, so it tends to colonise faster and more reliably. Spore syringes are cheaper and offer more variety, but are never fully sterile, so incubate them slightly cooler to let the mycelium outrun any stragglers.
Whatever you inoculate with, give the mycelium a clean start: wipe the rubber port, work in still, draught-free air, and flame the needle. Most failed runs trace back to a sloppy injection rather than a bad tub. We stock the sterile gear for it (a still-air box, wipes and gloves) in sterile and lab equipment.
Risk, reversed
The Sterile Guarantee
We guarantee the tub, not the grow.
Every SpawnTub is made fresh and arrives sterile and sealed. If one shows contamination on arrival, before you have inoculated it, send us photos and we will replace it. What happens after you open it comes down to your technique and conditions, which no reputable seller can promise for you. So we stand fully behind the tub reaching you clean, and the troubleshooting below helps with the rest.
At a glance
The spec sheet
- Product type
- Sterile grain spawn, inoculate and expand into your own bulk
- Vessel
- Tub, filled to about two thirds for shaking
- Grain
- 400 to 450g (a quart jar's worth) of organic rye with added gypsum
- Inoculation
- Inject the self-healing rubber port, then shake
- Culture needed
- 3 to 4ml per tub, not included
- Air exchange
- HEPA-filtered (the pink filter, leave it on)
- Colonisation temp
- Around 24 degrees, 18 to 24 is fine if kept steady
- Mid-run shake
- Once, gently, at 60 to 70 percent colonised
- Use
- As spawn for bulk substrate, or fruited on its own
- Sold as
- 1 tub or a set of 3
- Made
- United Kingdom, fresh to order
- Suited to
- Gourmet species: oyster, Lion's Mane, Shiitake and similar
When things look off
Common issues
Because you do the inoculating and colonising, the odd thing can go sideways. Here are the common ones and what they usually mean.
Nothing happening
Usually patience or temperature. Check back in a few days. Cold slows colonisation right down while microbes carry on, so keep it steady and warm.
Colonisation stalled
Often a shake too hard or too often. The one mid-run shake should be gentle and done once. Beyond that, leave the tub alone to take hold again.
Green, grey or sour
That is contamination. A healthy tub smells earthy. Bin the affected tub and keep it well away from your clean ones.
Wet patches or pooling
Too much moisture, often from condensation. Keep the temperature steady and never put the tub on a heat mat.
Other kits
Want the whole grow in one box?
Common questions
Frequently asked
Aim for about 24 degrees while the grain colonises; anywhere from 18 to 24 is fine as long as it is steady, and keep an eye out for condensation. If you go on to fruit it, drop a couple of degrees to around 20 to 22. Avoid heat mats, they cause condensation.
No. A SpawnTub is the spawn stage, the living grain starter. To get a full harvest you expand the colonised grain into your own bulk substrate, or you can fruit the grain on its own for a smaller crop.
No. You add your own gourmet liquid culture or spore syringe, 3 to 4ml per tub. We stock gourmet liquid cultures separately.
Any legal gourmet species you have a culture for. It suits oyster mushrooms, Lion's Mane, Shiitake and similar.
On purpose. The space lets you shake the solution through the grain when you inoculate, and lets you do grain-to-grain transfers later. A packed tub cannot be shaken properly.
Shake once right after you inject to spread the culture, then once more when the grain is about 60 to 70 percent colonised to break up the lumps. Do that second shake gently and only once, or you risk stalling it.
No. The pink filter is the HEPA air exchange and it lets clean air in while keeping contamination out. Leave it on.
Send us photos before opening it and we will replace it, that is our Sterile Guarantee. Contamination that appears after you inoculate comes down to technique and conditions, so check the troubleshooting first.
Just quantity. One tub is enough for a single grow or to learn the spawn stage. Three lets you run different species at once or keep clean spawn going across several grows. Each tub colonises independently.
What customers say
Reviews
★★★★★ 5.0 from 29 reviews ✓ All from verified purchases
★★★★★✓ VerifiedOrdered 10 Nov 2021 · Reviewed 1 Dec 2021
Fantastic
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★★★★★✓ VerifiedOrdered 17 Jun 2023 · Reviewed 9 Jul 2023
Products are always contamination free and easy to use!
0
★★★★★✓ VerifiedOrdered 19 Apr 2025 · Reviewed 25 Jun 2025
work great but i think the tubs are a little weak, or im a oath, but i cracked them a little.
Reply from Cylocybe
Thanks for the reviews! Hmm.. Not really sure about the cracking, we've not really had that feedback before as far as I can remember. Where you trying to break up colonised grain when it cracked? If you could send us an email about it with a picture it will help me get a better idea of what might have went wrong. If it ruined your grow, we'll replace 'em :)
0
★★★★★✓ VerifiedOrdered 20 Jun 2022 · Reviewed 12 Jul 2022
Good stuff!! Will order again!
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★★★★★✓ VerifiedOrdered 22 Oct 2021 · Reviewed 6 Nov 2021
Extremely easy to use, high quality product!
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★★★★★✓ VerifiedOrdered 7 Jun 2022 · Reviewed 30 Jun 2022
Easy to use spawn tub. Just colonise, incubate and wait for the mycelium to do its thing 😉
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Ask the community
Questions and answers
Q
Do I need to sterilise the tub before I inoculate
A
"Completely sterile and ready for inoculation"
It's already sterile :P
For cultivating legal gourmet mushroom species only.Sold as a sterile substrate kit for home cultivation. We trust you to be responsible.