Our most popular kit, and the one that teaches the real method. You inoculate the grain yourself, run it through sterile coir, and fruit a proper harvest in the included tent.
For cultivating legal gourmet mushroom species only. A gourmet liquid culture or spore syringe is not included.
Made in the UK filled and sterilised fresh to order
Sterile guarantee arrives sterile or we replace it
You inoculate it any gourmet species, your choice
Fresh to order dispatched in about 3 working days, plain packaging
DifficultyIntermediate, you inject a culture
Time to first harvestAbout 4 to 6 weeks
YieldXL 500 to 600g, XXL 800 to 1000g+
GrowsGourmet species, your choice
The short version
A two-stage gourmet mushroom kit. You inject a sterile grain SpawnTub with your own culture, let it colonise, then mix the colonised grain into the kit's sterile coir and fruit it in the included tent. The XL gives around 500 to 600g of fresh mushrooms and the XXL around 800 to 1000g, over several flushes.
How it works
How a MonoBox grow works
Five stages take you from a sealed sterile kit to a tray of mushrooms. None of it needs a lab, just clean hands, a warm spot and a little patience.
1
Inoculate the grain
Fit a fresh needle and inject your gourmet culture into the grey rubber port on the SpawnTub lid, aiming for the edge of the grain. Give the tub a shake to spread it through, which speeds colonisation up. Work somewhere clean and draught-free.
XL: 1.5 to 2ml. XXL: the same into each of the two tubs.
2
Colonise the grain
Keep the SpawnTub in the box it arrived in, somewhere steady. Aim for around 24 degrees, though anywhere from 18 to 24 is fine, just keep it consistent and watch for condensation. Skip the heat mat. Leave it alone until the grain is solid white with mycelium, and do not open it before then.
About 2 to 3 weeks.
3
Mix into the substrate
Tip the fully colonised grain into the kit's sterile SteriCoir, break up the clumps so the grain spreads evenly, then finish with a thin layer of coir as a casing. The coir comes pre-sterilised, so there is no microwaving step.
4
Colonise the substrate
Lid on, kept at the same steady warmth. This is the make-or-break stage: you want the mycelium to run through the coir quickly. Give it a few extra days after it looks finished so the centre catches up.
Around 10 days.
5
Fruit your mushrooms
Move the colonised cake into the grow tent and drop the temperature slightly, to around 20 to 22 degrees. The humidity comes from the substrate, so you do not mist it. A small slit in the tent plus a fan in the room gives it the fresh air it needs. Harvest each mushroom just as the veil under the cap begins to tear, then dunk the cake in water between flushes for more.
First pins in 3 to 7 days.
Why this one
What makes a MonoBox different
Most grow kits arrive already colonised, so all you do is mist and wait. A MonoBox arrives sterile and you do the inoculation. Here is what that one difference buys you.
A sterile MonoBoxA pre-colonised kit
SpeciesAny gourmet culture you inoculateFixed, whatever it was grown with
Shelf lifeSealed and sterile, keeps for monthsAlready growing, best used soon
What you learnThe real grain-to-bulk methodLittle, you just mist and wait
HarvestA full bulk substrate, several flushesA smaller pre-grown block
Best forAnyone who wants to actually growA zero-effort beginner gift
Why it works
How we make it sterile
Sterile is the whole point of the kit, so it is worth knowing what that actually means here. The grain you inoculate is the one part that has to be perfectly clean, and this is how we get it there.
Autoclaved
Each SpawnTub is heat-sealed in an autoclave bag and sterilised in distilled water at 121 degrees for 90 minutes.
Cleanroom sealed
It then passes through a HEPA-filtered corridor to a cleanroom, where a suited operator handles it in front of a 12 foot laminar flow hood.
Desiccant dried
It is rebagged with a desiccant sachet that pulls out any residual moisture, starving stray microbes, and heat-sealed shut.
Worth noting
No process is ever perfect, which is exactly why every kit is backed by the Sterile Guarantee further down.
In the box
What's included
Two sizes. Both are complete bar the culture, which you add yourself.
XL MonoBox
Needs 1.5 to 2ml of culture
1.6L HEPA-filtered grow box
1000ml SteriCoir sterile coco-coir substrate
1 sterile grain SpawnTub (1L tub, about 650ml of grain)
XL grow tent
Hygiene kit: chlorhexidine wipes, hand wipes, face mask
Sterile gloves (optional, but advised)
XXL MonoBox
Needs 3 to 4ml of culture
3.1L HEPA-filtered grow box
2000ml SteriCoir sterile coco-coir substrate
2 sterile grain SpawnTubs (about 1300ml of grain in total)
XXL grow tent
Hygiene kit: chlorhexidine wipes, hand wipes, face mask
Sterile gloves (optional, but advised)
The one thing you add
What you'll need
The culture is not included.
A MonoBox is sterile and ready to inoculate, so you supply the living part: a gourmet liquid culture or spore syringe. The XL needs 1.5 to 2ml, the XXL needs 3 to 4ml. 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 grows trace back to a sloppy injection rather than a bad kit. We stock the sterile gear for it (a still-air box, wipes and gloves) in sterile and lab equipment.
Every kit 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 kit reaching you clean, and the troubleshooting below helps with the rest.
At a glance
The spec sheet
Kit type
Two-stage, grain spawn into bulk substrate
Vessel
HEPA-filtered grow box, plus a grow tent to fruit in
Substrate
SteriCoir pre-sterilised coco-coir (no microwaving)
Spawn
Sterile rye-grain SpawnTub, a 1L tub holding about 650ml of grain (XXL has two)
Inoculation
Inject the SpawnTub's rubber port, then shake
Culture needed
1.5 to 2ml (XL) or 3 to 4ml (XXL), not included
Colonisation temp
Around 24 degrees, 18 to 24 is fine if kept steady
Fruiting temp
A little cooler, around 20 to 22 degrees
Time to harvest
About 4 to 6 weeks from inoculation to the first flush
Yield
XL around 500 to 600g, XXL around 800 to 1000g, over multiple flushes
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 growing, the odd thing can go sideways. Here are the common ones and what they usually mean.
Nothing happening
Usually patience or temperature. Trace the mycelium edge with a marker and check in a few days. Cold slows it right down.
Yellow liquid
Normal. That is metabolites, the mycelium's own waste, not contamination.
Green, grey or sour
That is contamination. Bin the affected part and keep a contaminated kit away from your others.
Thin stems, no pins
Not enough fresh air. Widen the slit in the tent or add a little more airflow in the room.
Aim for about 24 degrees while it colonises; anywhere from 18 to 24 is fine as long as it is steady, and keep an eye out for condensation. Drop it a couple of degrees, to around 20 to 22, for fruiting. Avoid heat mats, they cause condensation.
No. A clean, draught-free room and the included wipes, mask and gloves are enough for most people. A still-air box lowers the risk further if you want one, but plenty of growers do fine without.
Any legal gourmet species you have a culture for. It suits oyster mushrooms, Lion's Mane, Shiitake and similar. We sell gourmet liquid cultures you can inoculate it with.
No. You add your own gourmet liquid culture or spore syringe. The XL needs 1.5 to 2ml and the XXL needs 3 to 4ml. We stock gourmet liquid cultures separately.
Roughly 2 to 3 weeks for the grain to colonise, about 10 days for the substrate, then a week or so to fruit. So around 4 to 6 weeks from inoculation to the first flush, depending on species and temperature.
Liquid culture has known, predictable genetics and can be incubated warmer, so it colonises faster and more reliably. Spore syringes are cheaper and offer variety, but are never fully sterile, so incubate them a little cooler.
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.
With good conditions the XL gives around 500 to 600g of fresh mushrooms across multiple flushes, and the XXL around 800 to 1000g. The first flush is always the biggest.
What customers say
Reviews
★★★★★4.9 from 350 reviews ✓ All from verified purchases
★★★★★✓ VerifiedReviewed 4 Jun 2025
A great place to start if you're interested in growing your own medicinal or gourmet mushrooms. Works every time.
★★★★★✓ VerifiedOrdered 10 Apr 2023· Reviewed 17 Jun 2023
Made things easy for a first time newbie. Followed all the steps carefully - in particular making sure the temperature range was right. I found each stage took a bit longer than expected but played the long game and let things develop as they needed to. The final stage in particular seemed to take ages with no action and no sign of any actual mushrooms developing despite a vigorous web of mycelium evident. But all good things come to those who wait and, hey presto, just as I was giving up hope that anything would happen, 2 months later I have harvested my first flush - over 200g of fine mushrooms. Now hoping for a second flush..
Reply from Cylocybe
Love this review, Rupert. Most folks never get around to leaving one after seeing results, so it's VERY appreciated that you put the effort into writing this. Regarding duration it takes - it changes wildly on numerous factors, especially for gourmet mushroom spores because there's a TONNE of genetics with different traits - a lottery. That's when things get really fun though... strain isolation and cloning for characteristics you want like speed, look, size, etc.
0
★★★★★✓ VerifiedOrdered 16 Jun 2022· Reviewed 7 Jul 2022
thanks Cylocybe, good instructions with this kit
0
★★★★★✓ VerifiedReviewed 1 Sep 2025
Great piece of kit, highly recommended
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Ask the community
Questions and answers
Q
I'm currently on fruiting stage and don't have indoor grow light, will the amount of light at this time of year slow down the process. Also do you need to maintain the temps at all times, I'm currently moving from within a room during the day for the light, to a cupboard at night to maintain the temp. I'm currently considering buying a grow light but when I've been looking I'm not sure if I'll be buying a one that's insufficient for the process (this is a one I've seen, https://www.ebay.co.uk/itm/8000W-144LED-Grow-Lights-Full-Spectrum-Lamp-for-Indoor-Home-Garden-Veg-Plant-UK-/144122681671?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=710-127635-2958-0) Any help or advice would be great. Thanks
Anonymous ··
Waiting for an answer.
Q
Hi .. I got a xxl mono box with two 3ml spores of different strains. Should I have got two of the same strains?
Anonymous ··
A
As long as you’re talking about legal to grow mushroom spores and not strains of our microscopy spores then I’ll answer this question. XL MonoBox is 1 grow kit, XXL MonoBox is also 1 grow kit. If you want to grow multiple species or strains, you’ll need multiple grow kits because you can’t grow two types of mushroom from the one grow kit.
Nick Store team
Q
When it says 500g-1Kg of fresh mushrooms is that for the xl kit or xxl kit? Also is this for a first flush or in total?
Anonymous ··
Waiting for an answer.
Q
Can the tubs be reused?
Anonymous ··
A
Absolutely :) We will have re-fills available soon too for the Coir.
Nick Store team
Q
hi there. I'm a bit over time 17 days at spawning stage 25C but the white mycelium is not fully colonised I would say 75% and there is some green colour(contamination?) on top which I have removed. I have raised the temp slightly. should I keep going or remove to bag or start again? many thanks
Anonymous ··
A
Hi Thomas, something doesn't sound right. It should take around 7-10 days to colonise - not 17. It's almost definitely a temperature related issue as the mycelium is growing too slow (too cold or fluctuating non-stable temps are the biggest cause of that, by a country mile). Can you drop us an email through the contact form and we'll have a look at your setup? :)
Nick Store team
Q
I have an XL. Instructions which I followed say 1.5-2ml injected into SpawnTub, use SAB, keep at 26 degrees and full colonisation will take around 2-3 weeks. I am on day 15 going on 16 and have no sign of growth. Can you please advise?
Anonymous ··
Waiting for an answer.
Q
Currently just started my third flush with this kit and it seems to be going well so far, considering I don’t really know what I’m doing! I was wondering though, I seem to be getting loads and loads of little tiny mushrooms and then a few bigger ones. Is there a way to get them bigger? Also when I harvest do I have to harvest all the mushrooms at the same time or can I harvest just the big ones and let the small ones keep growing?
Anonymous ··
A
Hi there, sometimes this happens with the first flush and sometimes it’s just genetics. As long as you are following the guide, you are doing everything you can do. When cropping, do them all at once. And follow the instructions for the second flush - I have my fingers crossed for you getting an insane harvest of all big mushrooms :)
Nick Store team
Q
Do you need to keep them at a set temperature when growing in the tent ?
Anonymous ··
A
This information is also in the guide, but yes - fruiting temperature for mushrooms is important. If it’s too cold then you are going to struggle growing mushrooms at home. A consistent temp of 20-24c is a typical for many popular species. If you are struggling to meet those temps, take a look at our equipment section - especially the CyLab which is a heated fruiting chamber amongst other things.
Nick Store team
Q
In the description it says you need 3ml of spore solution for the XXL kit, however the instructions which come with the kit say 3-4ml for each tub (6-8ml in total). Which is correct?
Anonymous ··
A
We temporarily advised 1.5ml, but noticed some customers experiencing slower growth so went back to recommending 3ml.
Nick Store team
Q
Can you please upload the instruction manual for the Monobox XL?
Anonymous ··
A
If you haven’t received the instructions with your order, please get in touch via the contact form :) When we have some free time, we’ll implement a digital download function on the site though.
Nick Store team
For cultivating legal gourmet mushroom species only.Sold as a sterile substrate kit for home cultivation. We trust you to be responsible.
