Nature's Best
Soil Amendment.
Mix & Gro distributes premium Spent Mushroom Substrate — a CCOF & CDFA certified organic input that transforms how California growers feed their soil.
100% Spent Mushroom
Substrate (SMS)
Mix & Gro, LLC entered into an exclusive Master Distributor Agreement with a CCOF and CDFA Certified Mushroom Farm in California. Our agreement allows us to private label the spent mushroom substrate that the farm generates after they clean out their mushroom growing rooms.
SMS is derived from a unique compost blend specifically formulated to grow white button and crimini mushrooms — and it's one of the most nutrient-rich soil amendments available to California growers.
CCOF & CDFA Certified
Sourced from a California-certified organic mushroom farm, fully compliant for organic agriculture operations.
Private Label Available
Exclusive master distributor agreement means we can private label product for your brand or operation.
Custom Blending
Our network of soil blenders can combine SMS with any plant grow substance to match your unique requirements.
Flexible Delivery
Broad relationships with trucking companies give us the flexibility to deliver on your schedule.
Supporting Documents
Safety Data Sheet (SDS)
Official safety, handling, and storage guidelines for Spent Mushroom Substrate. Required reference for commercial and farm applications.
Download PDF →Product Information Packet
Complete overview of Mix & Gro's SMS product — sourcing, certifications, application guidance, and ordering details.
Download PDF →What Is Mushroom Compost?
An accessible introduction to mushroom compost — how it's produced, what it contains, and why it improves soil health and plant growth.
Download PDF →Spent Mushroom Substrate Overview
A detailed look at SMS as a soil amendment — nutrient profiles, organic matter content, and recommended use cases across crop types.
Download PDF →Monterey Mushroom Lab Test (Mar. 2024)
Third-party laboratory analysis of nutrient content and composition from our CCOF & CDFA certified Monterey mushroom source.
Download PDF →Sunland Lab Test
Independent third-party laboratory results verifying the quality, nutrient profile, and consistency of our substrate supply.
Download PDF →Penn State: Plant Nutrients & Mushroom Compost
University research examining how fresh mushroom compost affects plant nutrient availability — supporting evidence for SMS as a premium soil input.
Download PDF →
Our Team
At Mix & Gro, our team's expertise expands far beyond the talented colleagues in our office. Our business development model is centered on assembling a diverse group of professionals and companies who all add value to our customers.
Our substrate suppliers follow rigorous standard operating procedures to ensure their plant grow media meets the high-quality standards we offer to you.
We only want to sell you what you need — not just what we have. Our network of advisors helps us develop products to fit your needs, and our soil blenders can combine our substrates with any plant grow substance for your unique requirements.
Our broad relationships with trucking companies allow us flexibility to get our products to you when it's convenient for you.
Work With UsReady to Gro
with Us?
Tell us about your growing operation and what you're looking for. We'll help match you with the right product and volume.