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Extra Special (BulkMix) MycoJar² Grow Kit


Processed and bagged within an ISO Class 5 cleanroom.
This brand new and upgraded version of our extra special grow kit comes with 2x 1L MycoJars.

A premium grow kit which delivers the biggest flush sizes of any product we have yet offered on our site.

Recommended to people like us who love getting their hands dirty!

All grow kit products are for UK customers only at this time, sorry.

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  1. Slide both MycoJars out of the bags, discard foil
  2. Inject 2-3ml of a gourmet spore / culture syringe into each jar (around the glass sides is best)
  3. Shake the MycoJars to distribute the solution throughout the rye grain
  4. Leave MycoJars alone in a warm place to fully colonise (Place back into bags to keep the jars clean)
  5. Follow the rest of the guide until harvest

The white filters on the lids will stop dust and mould spores entering and allow clean air exchange.
NEVER open the MycoJars before full colonisation of mycelium or the kit will be ruined with contamination.

Click the ‘Instructions’ tab above to read our detailed guide
Includes photos of how to use the Bulkmix – it’s easy!

What’s Included

  • 2 x 1000ml MycoJars of Coffee-enhanced Organic Rye Grain Substrate and Gypsum (2/3rds filled for shaking)
  • Polyfil-Filtered and Inject-Thru™ lid system for ultimate contamination resistance
  • XL Ultra Grow Tent to fruit your mushrooms inside (32x49cm)
  • 1 litre Bulkmix recipe of coir and vermiculite within a heat-sealed bag
  • Hygiene Kit includes surgical gloves, alcohol wipes and hand wipe
  • Online Guide

Not included

  • Gourmet Spore or Culture Syringe


If you cannot use your grow kit right away, we would advise that you store it in a (clean) fridge for a maximum of 2 weeks.
If you can’t store it in a fridge, don’t leave it for any longer than 1 week.
The longer you leave it, the more moisture will be lost from the substrate and if too much moisture is lost, colonisation will just not happen.

Always inoculate your grow kits as soon as you possibly can!


  • This grow kit is tailored for all experience levels, for our biggest results yet!
  • MycoJars can take anywhere up to 6 weeks to fully colonise at optimum temperatures (shake at 70%)
  • Packaging may contain a small build up of water – the distilled water is sterile and nothing to worry about.
  • Does not come supplied with a gourmet spore or culture syringe.
  • Wood-loving species may not fruit on this substrate.


All grow kit products are for UK customers only at this time, sorry.
Product is made fresh to order – Please check our dispatch schedule here.
Only for use in cultivating species which are legal to grow – research the law.


Instructions for Extra Special (BulkMix) MycoJar² Grow Kit


For this stage, you will need:

  • 2 x Rye Grain MycoJars (supplied)
  • 1 x Surgical face mask (supplied)
  • 1 x Pair of sterile gloves (supplied)
  • Alcohol wipes (supplied)
  • Gourmet spores / liquid mycelium syringe and needle (not supplied)
  • Flame lighter (not supplied)

Make sure you and the room are clean and draft-free (no pun intended!). Fit your gloves and face mask - make sure your hands are clean and bone dry before fitting them or you won't get the gloves on, trust us!

Inject the required amount of solution through the rubber port in the lid. Flame sterilize the needle between each other kit you may have purchased (if you haven't purchased extra needles from us).

Now place the MycoJars back into the bags they arrived in to keep dust and other nasties off it - leave a gap in the seal so it can still breathe! Place somewhere at room temperature to begin colonising, they will turn completely white in time, so be patient. Don't put these jars in any direct sunlight.

When it looks complete, don't rush it - let it have another week.

1. Get organised

Choose a space to use as your 'lab' - An ideal room to use will be draft-free, such as a small cupboard. Kitchens and bathrooms are generally not suitable because of the increased risk of mould. Take everything you will need into your lab at this point, you want to keep air currents to an absolute minimum - close the door and keep it closed until you are finished! - to lower the odds of contaminant spores getting into the MycoJars.

2. Cleanliness

Take the time to ensure you are completely clean - have a shower, brush your teeth and change into fresh clothes. Before you begin the inoculation process, take your face mask out of the bag and secure it tightly to your face. Then, make sure your hands and forearms are clean - you can wipe them with the included Clinell hand wipe and let them completely air dry first or you'll struggle to put your sterile gloves on!

3. Inoculation

Give the syringe a good rattle and shake to help break any clumping. Remove the cap from the end of the syringe, unwrap the sterile needle and screw it on to the syringe. Remove the foil from the MycoJar and pierce the needle through the rubber port in the lid - inject the required amount of liquid around the sides of the jars.

When inoculating other grow kits with the same syringe, it's advised to flame sterilise the needle until it glows red hot, giving 15 seconds or a tiny squirt of liquid to allow the needle to cool down before injecting. Or you could purchase some extra needles and switch them over if you prefer.

Never wipe a needle with an alcohol wipe - this will only sanitise it. It's best flame sterilising for proper sterilisation.

4. Colonisation

Now it's time to leave the MycoJars in a safe place to fully colonise with mycelium. We recommend that you place the MycoJars back into the bags they arrived in to keep them as clean as possible for the next stages. Remember not to seal the bag fully to allow the growing mycelium to breathe!

It's recommended to leave the MycoJars to colonise in a room with indirect sunlight or light from a flourescent bulb.. although a dark cupboard won't do any harm. Just keep it out of direct sunlight and it will be fine!

Regarding heat, many species love very warm climates during colonisation but it can be a balancing act because so do bacteria!.. If your mycelium is going strong, it can outrun many types of bacteria and you will never know they were even present.

Keeping the colonising MycoJars somewhere between 18C and 26C is ideal. 26C will be noticeably faster than 18C but with some patience it will get there regardless.

If you are determined to have a warmer environment for faster colonisation times, we strongly advise against the use of heat mats as they can dry out the bottom of the substrate and stall colonisation. It's a far better idea to store your substrates somewhere with more balanced heat like a warm cupboard above a fridge or near the water boiler..

Generally, you will start to see mycelium growth after 10 days depending on optimum conditions - if not, just hang in there a while longer as you may have injected too deep to see any growth yet.. Injecting gourmet spores or culture close to the walls of the container (jars in this case) is of course going to show quicker results than injecting deeper into the substrate - and that's the most common reason we get emails saying 'I can't see any mycelium..'. Patience is key here!

It normally takes around 4-6 weeks for the MycoJars to fully colonise with white mycelium but again, this depends on a range of factors such as temperature, genetics, etc.

You can shake the jars to distribute the colonised grain - this will speed up the mycelium growth. But make sure to never shake the jars before 70% colonisation as this could completely stall the growth.

When the MycoJars have reached full colonisation, it's highly recommended that you leave it for an extra few days to allow the mycelium to consolidate.



For this stage, you will need:

  • 2 x Colonised MycoJars
  • Alcohol wipes
Take your two colonised MycoJars, inspect for cracks and when all is fine - hit the jars on something with a bit of bounce, like a clean bike tire or a roll of duct tape.
After a good few knocks, the grain will just break apart, separating into their individual kernels.
Be careful when doing this step - this is how it's always been done in the industry but it's not completely risk free (though we have never heard of an accident with grain jars!).
After you have broken up all of the grain, give the jars a clean with the included alcohol wipes.


For this stage, you will need:

  • 1 x Bag of BulkMix (supplied)
  • 1 x Tent for fruiting your mushrooms in (supplied)
  • 2 x Colonised MycoJars
  • Scissors
  • 150ml water
  • Microwave
  • Tin foil
Cut a corner of the BulkMix bag
Pour 150ml of water in
Move the substrate around the bag to ensure the water is spread throughout
Shake the contents down, away from the opening in the bag
Place in your (clean) microwave, making sure that the hole you cut is open, to allow for steam to escape
Microwave on high for 10 minutes
Remove the bag from the microwave
Leave it to cool - wrap in foil to reduce loss of moisture


Our preferred method to mix spawn and substrate is as simple as lasagne!
In a clean area, with clean hands..
Pour a layer of BulkMix, then grain and repeat this layering, making sure to finish with a coating of BulkMix on the top to cover any exposed grains.
Fold the bag down, making sure that white filter strips are still above the substrate (like in this photo) and secure with an elastic band or just fold it under itself!


Now leave the substrate to fully colonise again in the same environment/temperature as before.

This takes up to 1-2 weeks in optimum conditions.


When the substrate is fully colonised, remove the elastic band and unroll the bag.

Open the bag and fan air inside - you can use anything to do this, like a piece of cardboard.

Ideally, you will want to open and fan into the bag a few times a day.

This process of introducing more air into the substrate promotes the growth of mushroom pins.

Another tip for allowing more fresh air into the bag is to leave the top of the bag slightly open, securing the majority of it with paper clips/pegs. Do not leave the bag fully open as this will release too much of the humidity and the substrate will begin to dry out.

If the substrate does appear to be drying out, you should lightly mist it with water.

But - unlike our other grow kits which use perlite at the fruiting stage, it is not necessary to continually mist inside the bag with water as there should already be enough moisture stored within the substrate mix to provide the required humid environment, to at least the first flush of mushrooms.


When your mushrooms are ready for harvest, you can just twist and pull them away from the substrate.

When you have harvested all of your mushrooms from your first flush, you can expect to see more fruiting! (If you have looked after your grow kit well, you should achieve a few large flushes of mushrooms.)

But, eventually the mushrooms will use up all of the nutrients within the substrate and no further mushrooms will be able to grow.

If you follow these instructions carefully, you will have no problem in growing your own beautiful mushrooms..

Good luck and have fun!