Manual: Common Oyster Mushroom Spawn

Growing oyster mushrooms with grain spawn is a fun way to grow fresh mushrooms at home. Here is a step-by-step manual for successfully using common oyster mushroom grain spawn.

Use the spawn as soon as possible after you receive it, or keep it in the fridge for a few weeks at most.

What you need:

  • Common oyster mushroom grain spawn
  • Substrate (e.g. wood pellets, straw or spent coffee grounds)
  • Large plastic bag or growing container
  • Optional: Gloves face mask and/or alcohol for cleaning the working area

Steps:

  1. Preparing the substrate:

    • Hydrate the substrate by soaking it in water. Soak wood pellets and straw for 1-2 hours; spent coffee grounds are usually moist enough already after making coffee.
    • Let the substrate drain well until the moisture content is between 60-70%. That means the substrate feels moist, but no water drips out when you squeeze it in your hand.

  2. Pasteurise the substrate:

    • To remove competing fungi and bacteria, it is important to pasteurise the substrate. You can do this by placing the substrate in a pressure cooker and heating it at high pressure for 60-120 minutes. To pasteurise straw, submerge it in hot water (70-80°C) for 1-2 hours.

  3. Inoculation:

    • Wear gloves and a face mask to prevent contamination.
    • Work in a clean environment, preferably using disinfectant or alcohol to clean the work surface.
    • Open the bag of common oyster mushroom grain spawn.
    • Mix the grain spawn evenly through the cooled, sterile substrate in the plastic bag or growing container. Make sure the grain spawn is well distributed, so that the mycelium can spread quickly.

  4. Incubation:

    • Close the bag or growing container and make a few small holes for gas exchange.
    • Put the bag or growing container in a warm, dark place with a temperature between 20-25°C.
    • The mycelium should grow all the way through the substrate within 1-3 weeks. Check regularly for signs of competing fungi or bacteria.

  5. Fruiting:

    • Once the substrate is fully colonised, raise the humidity by putting the bag or growing container in a humid environment, for example in a humid room or by laying a damp cloth over the growing container. Provide enough air circulation to prevent mould growth.
    • Make bigger holes or cut openings in the plastic bag to give the mushrooms room to grow. If you use a growing container, open the lid or remove the cloth to lower the humidity and encourage the mushrooms to grow.
    • Keep the temperature between 15-20°C and provide a light spot, but not in direct sunlight.
    • Spray the substrate and the inside of the bag or growing container with water regularly to keep the humidity high. Make sure the substrate stays moist, but not soaking wet.

  1. Harvesting:

    • The common oyster mushrooms are ready to harvest when the edges of the caps start to curl up or when the caps have reached a diameter of about 5-10 cm.
    • Harvest the mushrooms by carefully taking hold of them at the base and twisting them loose. Try to take as little substrate as possible with you when harvesting.

  2. Second and further harvests:

    • After the first harvest the substrate can produce more common oyster mushrooms. Give the substrate a few days of rest and then repeat steps 5 and 6 for extra harvests. The substrate can produce fruiting bodies 3-5 times before the nutrients are exhausted.

  3. After the last harvest:

    • When the substrate no longer produces mushrooms, you can compost the used substrate or spread it in the garden to enrich the soil.

Enjoy growing your own oyster mushrooms!