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Mix with colonised grain for bulk growing

BulkMix™ is produced in our factory from coco coir, vermiculite and gypsum

Is this what’s used for ‘monotubs’…? Yes!


If you have colonised grain spawn and you want to turn it into a whole load of mushrooms, this is the product.

Choose to have this perfectly hydrated and sterile for immediate use with your spawn, or save yourself some pennies and do all of that yourself.

What’s included
  • Different volumes of BulkMix™ available
  • Filled within a breathable grow tent, like in the photos
  • Contains vermiculite, coir and gypsum


How much do I need for the substrate depth?

Aiming for a substrate depth of between  2.5″ to 4″ is ideal.

One way to figure out how much you need is to fill it up your chosen container with water to which depth you like.. If you put 6 litres of water in to get to the depth point, then that’s what overall volume of substrate and spawn you need..


What ratio do I mix spawn to Bulkmix™

1:1 all the way to 1:2.5 is common (grain : bulkmix / in volume)
eg. 1 litre of colonised grain : 1 Litre of BulkMix

Some prefer to do their ratios based on weight though.. There’s no perfect answer clearly.

The more grain you add, the quicker the colonisation will be which means a bit less risk in contamination getting a foothold.


How to use

We like to layer like a lasagne.. BulkMix > colonised grain > BulkMix > colonised grain… etc.
Leave a 1cm layer of BulkMix on top as a protective casing layer.


The perfect incubation temperature for your kit

After you’ve mixed your colonised grain with the BulkMix, make sure to cover it all over and put back into incubation at around 20C.

Incubating at hotter temperatures than this will speed up mycelial growth but it will also increase the rate at which other contaminants can grow – we want your chosen mushroom mycelium to take over the substrate, not anything else.

Once the substrate has finished colonising, move on to the fruiting stage.


Opting for non-sterile and doing it yourself?

Make sure to add enough water so it gets to ‘”field capacity” – where you can squeeze a fistful of it and it only expels a tiny stream of water for a second or two, then sterilise at 15PSI for 30mins using the same bag you receive it in. If you don’t have a pressure cooker or autoclave, you could pasteurise it or try microwaving it (not as thorough as sterilisation and may be too big to get into a microwave!)

If you are unsure, best going for the sterile version


Guaranteed Promise

We stand by the products we produce, but sometimes mistakes happen.. especially further down the line (during shipping).

If you have received a damaged product then you need to let us know immediately.
Letting us know weeks or months later will not fly with us..

If you end up suffering a contamination issue, we are here to help, so head over to our contact page and let us know immediately.. please be prepared to provide the pictures we ask for and don’t be offended when we ask (we need to).

We will not refund or replace an item in which a customer hasn’t made us aware of immediately, and who hasn’t provided us pictures for – so please inspect your items thoroughly.



Product is made fresh to order, we aim to produce and dispatch within 7 working days (Mon-Fri) from the moment we confirm payment.

Only for use in cultivating species which are legal to grow – research the law.


Extra advice

Can take around 7-10 days to fully colonise in optimum conditions, but it depends on a lot of factors.

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