CVG Substrate (Sterilised)

£10.50£23.00 inc. VAT

Our perfectly hydrated and sterile CVG mushroom substrate is a unique blend of Coir, Vermiculite, and Gypsum – expertly hydrated to field capacity using double-filtered water (no chlorine, chloramine, VOCs, or other nasties here!). Subsequently processed in our industrial autoclave for an extended sterilisation cycle; the result: a perfectly produced substrate for your mushrooms.

Sterilising the substrate mix not only eliminates 100% of any contaminants but also helps to break down the main coir content, making it more easily digestible for the mycelium. Sterilised coir will colonise faster and cleaner than non-sterilised CVG substrate and is much easier than making it yourself – sterile CVG is the preferred substrate for numerous mushroom species, providing all the micronutrients, hydration and bulk your mycelium needs for healthy and bountiful mushroom production.

Correct hydration is also incredibly important – too little water, and you’ll miss out on high yields; too much, and you will increase colonisation times and open your doors to bacterial contamination. Don’t take the risk and buy from the pros… we’ve been producing sterile mushroom substrate for 6 years now. We ensure every single bag leaves our facility in tip-top condition, perfectly mixed, expertly hydrated and sterilised in our computer-controlled industrial autoclave.

Available with a number of additional supplements: chopped straw, chicken manure.

For best results, use in combination with our best-selling sterilised rye grain bags; they’re a match made in heaven 😇.

Please familiarise yourself with the FAQ's & drop-down sections below before placing your order.

+ Lead Times

For freshly produced, high-volume or ‘made to order’ items there could be an additional delay in dispatching your order, this is known as a ‘lead-time’ or production time. Our estimated lead times for this product are shown below:

  • Orders less than 48 units: no lead time
  • 120 units: 1 week
  • 240 units: 10 days
  • 480 units: 2 weeks
  • 860 units: 3 weeks

Please contact us if you require larger orders sooner; we may be able to expedite your order for a small fee.

+ Technical Information
  • Available in 1kg and 3kg bags.
  • Genuine Unicorn Filtered Bags.
  • Made using double-filtered water, passed through an activated carbon filter.
  • Horticultural gypsum adds essential minerals and trace elements to support vigorous mycelial growth.
  • We use these ourselves in our own mushroom production facility.
  • Sealed with a 6mm sealer before being sterilised in an extended autoclave sterilisation cycle.
  • Suitable for numerous mushroom species.
  • Orders of 6 bags or more will often be supplied without bag tag numbers or sterilisation indicator strips to keep prices low for our bulk customers.
+ Shipping & Returns


Orders are usually dispatched same or next working day, but please allow up to 3 working days for dispatch + any additional product lead times as sometimes we can get incredibly busy.

We package our products in plain, unbranded, reinforced cardboard boxes with plenty of internal protection.

Our shipping couriers may leave parcels with a neighbour or in a safe place if nobody is home to receive them. To avoid this from happening, please choose the designated signed for service at checkout (and ensure you are in to receive the parcel, else it’ll be held at your local sorting office or returned to us) – We cannot be responsible for lost, stolen or missing parcels where the signed for shipping service have not been selected at checkout.

Items which have have been returned to us due a failed delivery may be subject to a redispatch or re-stocking fee, so please ensure packages any held packages are collected from your local sorting office within 2 weeks to save them being returned.

We strongly advise people upgrade their shipping to ‘DPD Express Tracked‘ service at checkout as we find this to be the quickest, safest and most reliable service. Royal Mail do occasionally have delays in their sorting offices.

For more info, please see our shipping, returns and replacements policy.

+ Quantity Discounts

Our most recent wholesale price list can be found here: Sterilised CVG Substrate Bags – Wholesale Price List – Jan 2024

Purchasing Disabled

Due to recent flooding in our warehouse and processing facilities, we're only accepting orders for a limited number of our products, which are available for purchase on our eBay store.

£10.50£23.00 inc. VAT

Purchase one of these today to earn ~10-23 POINTS worth £0.50-£1.15 to redeem on your next order.
Purchase one of these today to earn ~10-23 POINTS worth £0.50-£1.15 to redeem on your next order.
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Shipping & Returns info | Free Shipping Available Over £90 🚀
⇓ More product information below ⇓

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5-Star Customer Testimonials

Over 2,300 rave reviews and counting! Here's a random selection (different on every page)...

Very pleased with my recent order. Very high quality product with fast delivery and neat packaging. I'm seeing Great result, especially following the well written instructions. Also received quick and clear responses with any queries I had. Definitely will come back to order more soon. 😊

⭐⭐⭐⭐⭐Antoni Kurpiel on Google

Best spawn bags on UK market! I've ordered couple of times from Maya and was never disappointed! Quality bags, quality packaging & best customer service! 5/5 👍🏼👍🏼

⭐⭐⭐⭐⭐Kamilo Kamil on Google

k, speedy delivery, I wouldn't go anywhere else for my mycology needs. Thank you so much.

⭐⭐⭐⭐⭐Steve on Trustpilot

These guys are great and definitely worth the coin! I don't get grow bags from anywhere else now but have found these have the perfect ratio of contents and have never been contaminated so it is clear its very sterile.

⭐⭐⭐⭐⭐Danny Darka on Google


Answers to frequently asked questions.

Do you accept cash payments for larger orders?

Yes, we accept cash payments, but would require a none-refundable 20% deposit to be paid to add your order to our jobs list. The remaining balance of your order can be paid in cash on collection (we don't accept cash in the post). Once your order is ready, it will need to be collected and paid for in full within 3 weeks, else we reserve the right to re-sell your order and your deposit will not be refunded.

To pay a cash deposit, please process your order online as normal, select whichever payment method you wish, and use the following discount code at checkout to take 80% off the order, leaving a 20% deposit: cash-deposit-20

Note that this discount code is only to be used to leave a 20% deposit for cash collection orders only. Please make contact with us before to discuss lead-times and collection windows.

There is a minimum order value of £500 to pay a cash deposit.

How will my product be packaged and shipped?

We put a lot of time and money to ensure our parcels are sent out so that they reach you safely and undamaged.

If your item will go in a box, it will be sent out in a discreet, plain, sturdy, double-walled cardboard box of appropriate size, with no branding packaging tape and plenty of internal packaging protection to avoid any damage during transit (though sometimes accidents can happen, but it's rare).

Smaller items which are sturdy and light will be sent out in plain, unbranded, padded envelopes.

All pallet orders are professionally strapped and wrapped with corner protectors.

We try to minimise the use of excessive packaging where can, to help save mother nature and all her gloriousness.

Scroll down to see a section on our Shipping & Returns info, with links out to our policies

Can I collect my order from your facility?

For larger orders that would otherwise typically go on a pallet, that's fine, but generally speaking, we'd prefer to ship to an address. Please contact us before placing your order if you want to collect your order to see if we can accommodate it. We are based in the Forest of Dean. We've got a busy warehouse where we do our thing, but we don't (yet) have a shop.

What is field capacity?

Field capacity when talking mushroom substrate refers to how much water content the substrate holds. Too much water and the mycelium will be swimming, and they’re not good swimmers… too little water, the mycelium will be thirsty and there will not be enough water in the substrate to produce lots of delicious mushrooms. As mushrooms are 80-90% water, they need lots of water to grow (but not so much that they can’t grow).

Obtaining the perfect substrate hydration is key, and comes with experience. We’ve been doing this for 6 years, so we know what we’re doing and will make sure each and every bag which gets dispatched is perfectly hydrated to avoid bacterial contamination and to maximise yields.


No fuss Shipping, Returns & Guarantee.

  • We aim to dispatch orders within 2 working days (Monday-Friday)
  • Free shipping option for orders over £90.00 - Shipping Policy
  • No questions asked returns & refunds policy - Returns & Refunds Policy

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