Spent Mushroom Substrate (Box of 5 Blocks)
Spent Mushroom Substrate (Box of 5 Blocks)
What are these good for?
These spent mushroom substrate blocks are produced from hardwood sawdust and USDA-organic soy hulls following mushroom harvest. They contain organic matter and residual fungal biomass typical of spent substrate and are commonly used as:
soil amendment
compost ingredient
vermiculture feedstock
compost tea input
Mulch
…and more!
Want a bulk order?
Spent substrate blocks are expensive to ship due to their weight. If you want many blocks for a major project, but don’t live in pick-up distance, please let us know! We are more than happy to work out freight shipping or another option. You can reach us directly at kevin@funjshrooming.com or go to our contact form.
Important Note:
These blocks are sold as a composting and soil-amendment byproduct only. They are not intended for mushroom cultivation or food production. Biological activity naturally varies, and additional mushroom growth is not expected or guaranteed.
If mushrooms appear and are consumed, identification and consumption are solely the responsibility of the user.
Please read the full disclaimer below.
Please read the complete disclaimer about spent mushroom substrate below:
Updated 3/22/2026
Spent Mushroom Substrate (“SMS”) Disclaimer
Please read this disclaimer carefully before using or handling your SMS blocks. By accepting delivery of these blocks, you acknowledge and agree to the following terms:
1. Intended Use
Primary Use: These SMS blocks are sold solely for composting and soil-amendment purposes.
Secondary Use (At Your Own Risk): Some customers choose to place the blocks in outdoor garden beds to attempt further mushroom cultivation. We do not guarantee fruiting success, and any such use is entirely at the user’s own risk. If the user chooses to grow mushrooms with spent mushroom substrate, FUNJ Shrooming Company LLC is not responsible for mushroom identification, harvest, preparation, or consumption decisions made by the user. Any use of this product for food production or consumption is outside its intended purpose.
2. Product Condition
“As‑Is” Sale: Blocks are shipped “as-is,” with all visible mycelium and after all marketable mushrooms have been harvested. We make no promises regarding appearance, microbial composition, mycelium species, or residual nutrient content.
Natural Variability: Because these blocks are organic and biologically active, you may observe:
Mold growth
Colonization by other fungi, bacteria, insects, or microorganisms
3. Health & Safety
Allergens & Irritants:
Wood dust, soy proteins, and fungal spores can trigger allergic reactions or respiratory irritation in sensitive individuals.
Wear gloves and, when handling large quantities or powdery material, consider a dust mask or respirator.
Pathogens & Contaminants: While we follow good manufacturing practices, SMS is not sterile after the harvesting process. As it is a natural, organic product in the process of decomposition meant for composting purposes, you assume all risk of exposure to potential pathogens (e.g., bacteria, molds).
Not for Consumption: Under no circumstances should this product be ingested or used as animal feed.
4. Limitation of Liability
The following are limitations of liability for FUNJ Shrooming Company LLC to the fullest extent permitted by applicable law.
No Warranty: We expressly disclaim any and all warranties – whether statutory, express, or implied – including but not limited to warranties of merchantability, fitness for a particular purpose, or non‑infringement.
Assumption of Risk: By using or handling this product, you assume all risks associated with handling biologically active organic material, including but not limited to allergic reactions, respiratory irritation, microbial exposure, or illness.
Maximum Liability: In no event will FUNJ Shrooming Company LLC or its affiliates, officers, employees, or agents be liable for any indirect, incidental, special, consequential, or punitive damages arising out of or relating to your use of this product, even if advised of the possibility of such damages. Our total liability for any claim related to this product is limited to the purchase price paid.
5. User Responsibilities
Proper Handling & Storage: Store in a cool, dry location away from direct sunlight. Wash hands thoroughly after handling.
Regulatory Compliance: You are responsible for complying with any local regulations regarding the use, composting, or disposal of organic agricultural materials.
Disposal & Composting: Incorporate into your compost pile or soil per standard composting guidelines. Do not dispose of blocks in storm drains, waterways, or municipal trash without checking local rules.
6. Non-Commercial Use; Resale Restriction; Indemnification
These SMS blocks are sold as a soil-amendment byproduct. They are not intended for commercial food production. Any cultivation of mushrooms from these blocks is for personal, non-commercial use only.
No Commercial Resale: You agree not to sell, trade, or distribute mushrooms harvested from these blocks to the public, including at farmers' markets, to restaurants, or through retail outlets.
Indemnification: If you violate this restriction and sell mushrooms grown from this substrate, you agree to indemnify and hold FUNJ Shrooming Company LLC harmless from any and all claims, damages, or legal fees arising from the consumption or sale of those mushrooms.
