How Mushroom Spawn Is Created in the Lab

Mushroom spawn is the foundation of every successful mushroom crop. Whether you're growing oyster mushrooms, shiitake, or Lion’s mane, the quality of your spawn determines colonization speed, yield potential, and resistance to contamination. In a professional mushroom farm, spawn is produced inside a sterile laboratory environment to guarantee clean, vigorous mycelium.

Step 1 — Starting With Pure Mycelium

Spawn production always begins with a pure culture. This is typically created by:

• Isolating mycelium on an agar plate

• Cloning tissue from a high-quality mushroom

• Starting from spores when developing new strains

Agar plates allow the lab technician to see the growth pattern clearly and ensure the culture is free of contaminants.

Step 2 — Expanding the Culture

Once a clean agar plate is established, a small piece of mycelium is transferred into a liquid culture or directly onto sterilized grain in a jar.

Liquid culture speeds up colonization, but grain jars remain the industry standard because they produce strong, resilient spawn suitable for large-scale production.

Step 3 — Preparing Grain for Spawn

Grain is the ideal food source for mycelium. To prepare grain spawn, we:

1. Hydrate the grain (usually wheat, millet, or rye)

2. Cook it until plump but not mushy

3. Dry the surface moisture to prevent bacterial growth

4. Load the grain into jars or bags

5. Sterilize for 90–120 minutes in a pressure sterilizer

This process ensures the substrate is completely free of competing microbes.

Step 4 — Inoculating Grain in a Sterile Environment

Inside a laminar flow hood, the clean grain is inoculated with agar wedges or liquid culture. The sterile airflow protects the mycelium from contamination during transfer.

The jars or bags are sealed and placed in a warm incubation room.

Step 5 — Incubation and Colonization

Over the next 10–21 days, depending on species and strain, the mycelium spreads through the grain. Once fully colonized, the grain becomes mushroom spawn — the “seed” used to inoculate bulk substrates.

Good spawn has:

• A fresh mushroom aroma

• Strong white mycelium

• No wet spots, discoloration, or off-odors

Why Quality Spawn Matters

High-quality spawn produces:

• Faster colonization

• Stronger yields

• Better resistance to contamination

• More consistent mushrooms for home cooks and chefs

For a mushroom farm, flawless lab work means better performance in the fruiting room and predictable harvest cycles.

If you are interested in learning more about our 4.0 Farm click here.

An educational resource on mushroom cultivation, including spawn preparation basics from Cornell.