Agar Media

Organic, pure, laboratory-grade gelidium agar powder and media premix

Organic Agar and Media Premix

(Prices listed are suggested donation)
Pure from the Source

We use only the highest quality bacteriology-grade organic agar powder. Available in half-pound and one-pound bottles.

"Blagar" Agar Media Premix

Our all-time favorite recipe, this jet-black agar media is packed with nutrients to keep your fungus happy and healthy. Just mix with water, sterilize and enjoy!

We use only the finest organic ingredients and prepare each batch by hand to ensure the perfect balance.

Directions: Mix 25 grams media with 500 mL water (50 g / L). Sterilize for 45 minutes at 15 p.s.i. and pour while hot.

Organic Matters

Mushrooms bioaccumulate toxins at many times the ambient levels of their environment. While this is good news for our soils, it's not for our bodies. With ever-increasing concentrations of pesticides and other toxins in our soil, food and water, it's more important than ever to find sources we can trust. 

At Fertile Substrate, we are meticulous about our ingredients, from our spring water to the pastures where we wrangle the choicest poops. We believe that every detail has significance, and we are dedicated to our craft. It won't be hard to see the difference, and we promise that your fungus will thank you, too.


Info & Terms

We are committed to providing exceptional customer service.

How It Works

For both privacy and security, we do not process credit cards on this website. Instead, after you place an order, you will receive an email with a link to pay using a secure, trusted third party (or instructions if paying with cash). Unpaid orders will be cancelled after 7 days (30 days for cash orders).

We do our best to process invoices and ship orders within 1-3 business days.


We do not sell or distribute any personal customer data to any third party for any reason.

Cancellation Policy

Excluding custom orders, your order may be cancelled for a full refund at any time until they have been shipped. Once an order is shipped it will not be refunded.

Return Policy

Due to the perishable nature of live biological specimens, we do not accept returns. In the rare case that you should find, with reasonable assurance, that our products were compromised in any way upon arrival, we will promptly replace them at no cost to you. We do not offer refunds after products have been shipped.

Lost or Damaged Packages

When an order is shipped, we provide tracking information. If a package is lost or damaged in transit, we will work with the postal carrier to recover the cost and send a free replacement. However, we are not responsible for orders which are lost or misplaced after they have been delivered by the carrier.


We reserve the right to refuse service to anyone for any reason.