Mushroom Spawn Stage

Mushroom Spawn Stage

The spawn stage is a critical phase in the mushroom cultivation process that serves as an intermediary step between the initial mycelium culture and the final fruiting stage. In essence, this stage involves expanding a small, fully-colonized mycelium culture into a larger substrate material. This is often done using grains, sawdust, or other types of substrate that are conducive to mycelial growth.

The importance of the spawn stage cannot be overstated. It not only facilitates rapid and healthy mycelial expansion but also lays the groundwork for a successful fruiting stage. Properly executed, the spawn stage ensures that the mycelium is well-distributed, robust, and free from contaminants, setting the stage for an abundant harvest of mushrooms.

Understanding the nuances of the spawn stage can be the difference between a fruitful yield and a cultivation effort that ends in disappointment. Therefore, gaining a comprehensive understanding of the procedures, materials, and conditions that affect this stage is crucial for any aspiring or experienced mycologist.

This guide aims to provide an in-depth look at the spawn stage, from the types of spawn you can use to the intricacies of inoculation and incubation, to help you achieve a successful mushroom cultivation process.

Types of Spawn and Their Applications

The type of mushroom spawn you use can vary depending on the mushrooms you are growing and whether you are cultivating them indoors or outdoors.

Grain Spawn

Grain spawn is commonly used for cultivation because of its quick colonization time and ease of use. It is made from grains like rye, wheat, and corn. I primarily use wild bird seed (WBS) for home cultivation. Grain spawn should be used as soon as possible for optimal results, but it can be stored for a short time under refrigeration.

Guide to Grain Spawn

Sawdust Spawn

Sawdust spawn is usually used for wood-loving mushroom varieties like Shiitake and is ideal for outdoor applications. Common wood types for sawdust spawn include oak and maple, and it can be purchased from specialized suppliers. Like grain spawn, it's best used as soon as it's fully colonized and can be stored for a short period under refrigeration.

Plug Spawn

Plug spawn consists of hardwood dowels colonized by mycelium and is generally used for outdoor log and stump cultivation. The use of a hand or power drill and hot wax is needed to inoculate logs. Plug spawn is robust but should be used within a month of full colonization to ensure vitality.

How to Make Grain Spawn

{GPT, please write this section using the topics below}

-Ingredients needed -Mixing ratios

The Importance of Hydration

Proper hydration of the spawn substrate is crucial for successful colonization. It provides the mycelium an adequate water source to metabolize nutrients, which in turn fosters optimal growth conditions. Neglecting this step can severely impact both the health and yield of your mushrooms.


Sterilization is a crucial step in the spawn stage of mushroom cultivation, as it eliminates potential contaminants such as molds, bacteria, and yeasts that can interfere with mycelial growth. Failure to properly sterilize your substrate and equipment can lead to failed colonization or yield losses. For effective sterilization, it's widely recommended to use a pressure cooker set at 15 PSI for a duration of 90 minutes. This ensures that the substrate is free from any microbial life, providing a clean slate for the mycelium to colonize.

Step by Step Guides

Wild Bird Seed Grain Spawn

How to Prepare Wild Bird Seed Grain Spawn

Step-by-step instructions for preparing wild bird seed as mushroom grain spawn. The most widely available and cost-effective grain spawn.

Wild Bird Seed Grain Spawn


Inoculation is the process of introducing mycelium into the sterilized substrate to initiate colonization. This step demands precision and aseptic technique to ensure that only the desired mycelium is introduced, avoiding contamination. Common methods include grain-to-grain transfer, liquid culture injection, or transferring a piece of mycelium-growing agar into the sterilized substrate. Properly executed inoculation is pivotal for achieving a successful, healthy, and high-yielding mushroom crop.


Incubation is the stage where the inoculated substrate is allowed to colonize under controlled conditions. The optimal temperature for most mushroom varieties during incubation ranges between 75-80°F (24-27°C). Time needed for full colonization generally varies from 2 to 4 weeks, depending on the strain and environmental conditions. Signs of healthy mycelial growth include a robust, white, web-like structure covering the substrate. It's essential to regularly check for full colonization; the substrate should appear fully white and consolidated, indicating that it's ready for the next stage of the cultivation process.

Monitoring and Troubleshooting

Regularly monitoring your substrate during the incubation phase is essential for early detection of problems that could hinder your cultivation project. Look out for the following signs of failed colonization:

  • Stalling Growth: If you notice that the mycelial growth has stopped or slowed significantly, it may indicate inadequate conditions or contamination. Consider checking the incubation conditions.
  • Unpleasant or Sour Odora: A foul smell usually indicates bacterial contamination. It's a sign that you should discard the substrate and start anew.
  • Colors Other Than White: The presence of colors like green, blue, or black suggests mold or bacterial contamination. Isolate the contaminated jars or bags to prevent the spread of contaminants.


  • Isolate the Problem: Remove any contaminated jars or bags from your incubation chamber to prevent cross-contamination.
  • Identify the Issue: Use the list of common contaminants to identify what may be affecting your substrate.
  • Take Corrective Action: Depending on the issue, you may need to adjust environmental conditions or discard the contaminated substrate.
  • Consult Trusted Sources: If you're unsure of the problem, seek advice from experienced cultivators or consult reliable mycology resources.

Common Contaminants

  • Trichoderma (Green Mold): A virulent green mold that grows rapidly, easily recognizable by its vibrant green spores. It has an earthy smell and can overtake a substrate quickly.
  • Penicillium (Blue-Green Mold): Appears as a bluish-green mold and often gives off a musty odor.
  • Bacterial Contamination: Usually presents as a slimy, discolored substrate and often produces a foul, rotten smell.
  • Dactylium (Cobweb Mold): Light gray and fluffy, resembling cobwebs, usually with a mildew-like odor.
  • Geotrichum (Lipstick Mold): Shows up as white or pink and turns to a lipstick red or orange. Typically odorless.
  • Trichothecium (Pink Mold): Features a pastel pink coloration and may have a somewhat fruity smell.
  • Neurospora (Orange Bread Mold): Bright orange in color, this mold has a musty odor.
  • Aspergillus (Black Mold): This mold is black or dark green and can have a strong, unpleasant odor.

Ready for Bulk Substrate Stage

Once your spawn is fully colonized, you're ready to transition to the bulk substrate stage. In this next phase, the fully colonized spawn is mixed with a bulk substrate like coco coir, straw, or a wood-based material, depending on the type of mushroom you're growing. This larger volume of substrate allows for extensive mycelial growth and sets the stage for fruiting. Make sure to maintain proper environmental conditions, including temperature and humidity, as you move into this more advanced stage of mushroom cultivation.

Bulk Substrate Stage
Amazon Storefront

Amazon Storefront

Our Amazon Storefront is a curated collection of products we recommend, hosted on Amazon. By purchasing through our storefront, you not only find quality mycology products but also support our website's growth through commissions we earn, enabling us to continue providing valuable content and recommendations.

Amazon Storefront

Stay connected
For any inquiries or assistance, feel free to reach out to us