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Posted October 14

Pre-Pasteurized Mushroom Compost

Starting at: $5.95

Please Choose:

Pre-pasteurized premium bulk substrate mushroom compost in a gusseted autoclave bag with filter patch. Shroom Supply mushroom compost is specifically formulated for growing mushrooms. It is free of any additives or chemicals and is to be used in conjunction with our mushroom grain spawn.

This choice bulk substrate is composed of five main ingredients including an organic compost specifically designed for mycological use, composted horse manure, organic coconut coir, vermiculite, and gypsum. This diverse blend of unique ingredients provides the perfect amount of nutrition for optimal mycelial growth, making it the ideal growing medium for mushroom cultivation.

Our premium mushroom compost comes pre-pasteurized and hydrated to the perfect moisture content, making it ready to use right out of the bag. Simply add colonized grain spawn, mix, and add to your fruiting chamber or grow bag. We recommend using two pounds of our grain spawn for every five pounds of compost. Once the substrate is fully colonized with mushroom mycelium, our casing mix can be applied in a thin layer to the top of the substrate. Please note that a casing layer is not required, but rather an optional ingredient that can benefit the growth of certain mushroom species.

This product comes heat-sealed in sterile, filter-patch mycobags and can be stored at room temperature for up to 14 days. If more time is needed, it can be stored in the freezer and dethawed before use.

All mushroom compost comes packaged in 5 lb. increments.

Made to order, usually ships within 2 business days.

Instructions: Bulk Substrate Tutorial

Erik C.
5 of 5 Stars
This mushroom compost is excellent. However this is made, they do a good job. The substrate is colonizing nicely and with no issues or contamination. Also, we have had no problems with shipping or communication from this company. We would recommend others here who are in search of mushroom supplies. Great customer service and great shipping. 5 stars.
Joseph C.
5 of 5 Stars
Best supplier on the internet got my package 3 days total I appreciate it so much and I will be ordering again very happy and I’m definitely recommending this to my friends and anyone who wants supplies to grow shrooms
Ambar b.
5 of 5 Stars
My packaged arrived super quick but usps rough handled my package and made a tear in the substrate and box I provided them with picture and Ryan made everything right and sent out a fresh batch of substrate the very next day I definitely will be picking up from them from now on thank you for you time and service ????????
Brendon M.
5 of 5 Stars
This sub is spot on. Side to side comparison proves it. Fast colonization, perfect field capacity. Very contamination resistant.
Zachary F.
5 of 5 Stars
Simply amazing, beyond grateful for this company. Love this substrate, ready to go and superior quality.
William H.
5 of 5 Stars
I don't usually write reviews unless i'm blown away, and...well....this is top quality. I wrote a similar review on your spawn bags but the same goes for this product. it was packaged neatly and is very high quality. Have not used yet, but you can just TELL from looking at these bags that they are the "ones". I will never use anyone else other than Shroom Supply. You all have the best customer service and are very friendly and informative. I can tell you really care about this hobby/passion and it shows in your products and service. Thank you, Shroom Supply!
Sean L.
5 of 5 Stars
Professional product from a professional company! Thank you!
Ash R.
5 of 5 Stars
What can be said that has Not Already been professed about this company and there attention to EVERY DETAIL. This compost has NEVER let me down.. ALWAYS arrives Completely STERILE and the automatic and accelerated growth is seen taking hold in under 24hrs of combining with spawn. Not to mention it has dramatically increased BOTH mushroom size and harvests. Has all the nutrition your mycellium projects require from first flush to the last. Very professional personnel with amazing tech support and Very Quick Responses should anything arise. The ONLY company I will EVER purchase from. Mush Love and THANKS for everything Fam Ash
anthony g.
5 of 5 Stars
Shrooms Supply you guys are a life saver. Saved me a lot of time and hassle. Tyvm!
andrew D.
5 of 5 Stars
Hands down my most favorite product on this site, perfect moisture content and I love how it's so nutrient rich and ready to go straight out of the package. For peace of mind and astounding colonization you cannot beat the price! MushLove for the shroom supply! Ten stars out of five!
5 of 5 Stars
Look-- Im a hard critic of online businesses. But i cannot find one reason to minus a star from these folks. I started with the A+ kit just to get a feel of what they supply. I also had a few questions along the way that were promptly answered by customer service. The result so far has been 3 AWESOME flushes from the same original substrate. Im more than pleased. And have already highly recommended shroom supply kits to my friends. I realize that there are many different teks out there. But if youre looking for convenience and discreetness of set-up, shroomsupply kit bags are the way to go. At any rate- could go on and on. Place an order for yourself and relax :-)
5 of 5 Stars
Excellent substrate that provided huge yields and massive fruit.
5 of 5 Stars
I am in love with this substrate! Very fast and rhizomorphic colonization with this sub resulting in very large fruits! 👍🍄
5 of 5 Stars
Best bulk sub out there, well worth every penny. Always comes sealed and ready-to-use!
5 of 5 Stars
First time I have tried it and so far it's working like a champ. Also the mail drop the ball and lost my order but some how still delivered the package empty lol. I email the company they fixed it no questions thanks.
5 of 5 Stars
Fastest shipping out of anything I've ever ordered off the internet. Fast colonization, will definately order again
5 of 5 Stars
This is an excellent bulk substrate. GIANT thick fruits. I mean huge. The flavor was so intense. I used only 1 of their sterilized rye bags and 4 pounds of this sub. It was fully colonized in less than a week. Didn't yield a whole lot bc of the ratio (instructions only call for 2.5 lbs. of compost but I used 4), but 9 mini shoe box tubs gave me produced over 20 Oz dry!
[Your Name Here]
5 of 5 Stars
Tyson already said it all. Look no further. This is what you want.
Tyson Iossi
5 of 5 Stars
This stuff is AMAZING! I got 6 and even 7th flushes before I decided to throw it out just to make more room. It was still producing a few mushrooms even on the 6 and 7th flush. Everything I've received from other vendors has always contaminated after the second flush and many times before that. Look no further, this is the best substrate you will find. It gives you the best possible yields with the most flushes, everytime! Thanks for making my job so much easier.
5 of 5 Stars
Great product and service. Faster colonization and better pin-set than any compost or pasteurized straw ive made. Cant beat pre pasteurized. Thanks guys
5 of 5 Stars
I barely started cultivating and having failed using the PF tek and also using monotubs, I have successfully harvested an abundance of fruits using this substrate. A+ rating, definitely worth every penny..
5 of 5 Stars
This stuff really is worth every penny, I mixed 1000 lbs of substrate and cooked 5 bales of straw this week. Id say this product outshines and outlast and outpreformes my attempts for 2 years consistently "Shroomsupply's Substrate has never contaminated on me". We got 4-5 flushes over 2 months with shroomsupplys I threw away half of homemade attempts, never thrown away SS's bulk sub's js
c pa
5 of 5 Stars
Have only used this since I started growing. & successful every time. Will be a return buyer.
5 of 5 Stars
Just spawned so I don't know about contams yet, but I'm the farthest I can be from the state they ship from and it still got here in 3 days. Very good primo poo. I'm sure the little ones will love it.
5 of 5 Stars
This stuff is the best yet and so is the customer service. Let me tell you I ordered a lot of stuff and the box was really in bad shape from UPS. So I had a product that ripped open and I told customer service that UPS played soccer with the box and described the tear in the bag. That's when they sent me a new bag. I am so grateful and can get the show on the road.
5 of 5 Stars
successful results with this stuff every time. only substrate i will use now. primo poop for sure!
5 of 5 Stars
5 of 5 Stars
I used to order my compost from HMC but their product has went downhill from when I was ordering years ago. This stuff is great though. It is a super dark, rich fluffy compost that out performs the other stuff I was using by a long shot! An excellent value for the money, fast shipping, and excellent customer service. KUDOS!
5 of 5 Stars
I haven't used anything else before this, I'm new to the hobby. But my mushrooms seemed to love it! They are located close to me so shipping was fast. Will order again =)
5 of 5 Stars
So, I received some of this substrate as a freebie with a large order. That will not affect my review. I've tried almost all of the bulks out there, and this stuff is the s#!t!! I WILL be buying my substrate from here on out from YOU. It went above and beyond my expectation. Mycelial growth is fast, and no contams. What more can you ask for? Honestly?
Justin Thyme
5 of 5 Stars
Have yet to try. Just wanted to thank you guys. I ordered a bunch of stuff and received a free sample Bag. Will start the "test" tomorrow. Update to come!!
5 of 5 Stars
This is by far the best bought bulk substrate I've had the pleasure of growing/experimenting with. I've tried numerous times to duplicate the substrate and results to no avail. Whatever it is you guys are doing is working, so keep it up. Also, I have yet to experience any contamination problems as well when using this, so pasteurization is superb, unlike many other mycology suppliers out there. I will vouch for this bulk substrate any day. -Clay
5 of 5 Stars
This compost works really well top notch and shipping is super fast A+++ for sure
5 of 5 Stars
Just wanted to say thanks for the speedy shipping, ordered on Friday, got my packages on Monday. Can't beat that. Also, great quality products as well. Already more results in less than 24 hours, than in a month using other products. Will be in contact soon to get more for sure. Thanks a lot!!
5 of 5 Stars
Your substrate is top-notch and is all I ever use.
5 of 5 Stars
Great product and super fast service. Return customer, bought TONS of substrate literally!
5 of 5 Stars
Best Compost Supplier on the web! A+++ service on every level. Thanks!
St. Pete portobello
5 of 5 Stars
Excellent Product No contams and perfect! colonizing super fast.