How To Make Mushroom
Grain Spawn

Learn To Make Mushroom Grain Spawn

Watch Our Video Tutorial Below

What Is Mushroom Grain Spawn?

Grain spawn is a little known secret weapon of the world of mushroom cultivation. It’s made from sterilised grains that have been inoculated with a live mycelium culture.

Grain spawn contains a lot of energy for mycelium to consume. It’s a bit like rocket fuel for mushrooms. Once it’s added to your substrate it takes off like wild fire. 

Mother Nature works her magic using spores but in a controlled environment you need to tip the scales in your favour by using clean high-quality grain spawn so you are doing your best to ensure success.

Grain Spawn & Liquid Culture Jars

What You'll Need

To make grain spawn you will need mushroom grow bags or reusable culture jars. Below I have listed what was used in our video tutorial but you may use the grains of your preference.

  • 8 spawn jars
  • 1 kg whole oats (or grain of your choice)
  • Large pot
  • Hot water
  • Pressure cooker
  • Live mycelium culture (agar, liquid culture or grain spawn)

Step 1. Hydrate The Grains

Bring a large pot of water to the boil. Turn off and add the whole oats. Allow to soak for 1 hour. 

The time required for hydrating the grains may vary depending on the grain used. Firmer grains may require more time. Adjust accordingly.

The grain should be soft enough to crush between 2 fingers with slight resistance. I like using whole oats as they are firm enough to maintain their structure while expanding with a large starchy core.

grains for mushroom growing

Step 2. Drain The Grain

Drain the grains. A fly screen doubles as an excellent sieve. Spread out the grains evenly to help them dry. Alternatively you may use a table with a flat cloth placed across it. The grains should still be damp but not dripping wet before moving onto the next step. This may take between 20 minutes – 1 hour depending on the weather.

Step 3. Pack And Sterilise

Pack the damp grain into reusable culture jars until they are two-thirds full. Leave space in the top of each jar.

Cover each jar with a piece of aluminium foil. Pack into pressure cooker and sterilise for a minimum of 90 minutes. 

How To Make Grain Spawn

Step 4. Inoculate With Mushroom Culture

Once the jars have cooled down they are ready to be inoculated with either liquid culture or agar.

The sterilised media is highly nutritious and susceptible to contamination. For this reason it is important to inoculate using aseptic technique.

If possible a flow hood should be used. Alternatively, you can undertake inoculations in a enclosed space with minimal airflow, such as a bathroom. 

Prepare the work space and syringe before removing the layer of aluminium foil. Using an open flame sterilise the needle and inject a few CCs of liquid culture via the silicone injection port of each jar. Flame sterilise the syringe between each jar.

Step 5. Shake Spawn & Wait

Once the mycelium has colonised 50% and 70% of the grain you may wish to shake the jar or bag of grain spawn. Doing so assists in dispersing the mycelium evenly throughout increasing colonisation speed.

Maintain at room temperature, darkness is preferred but not essential. The grain spawn should be ready for use within 14 – 21 days. 

Growing Oyster Mushrooms

Step 6. Put It To The Test

Now you’re ready to put your very own grain spawn to the test. The mycelium should look healthy and white. It’s normal for small amounts of yellow fluid to accumulate. These are a by-product of the mycelial mass called metabolites.

Try Cloning Mushrooms At Home

Learn how to create a mushroom culture at home from a fresh mushroom with our step by step video guide and tutorial.

PF Tek

Learn how to fruit mushrooms from brown rice flour cakes which can also be used in place of grain spawn. The PF Tek utilises a few household items to create nutritious cakes which can be inoculated with a liquid culture syringe.

Make Spawn With Sterilised Grain Bags

Each sterilised grain spawn bag has been carefully prepared by hydrating whole oats in a gypsum bath for 24 hours before sterilisation. 

The bag itself features a 0.2 micron filter patch to facilitate fresh air exchange without the contents becoming contaminated. 

Additionally, the self healing injection port allows the user to simply inoculate the grain using a liquid culture syringe with minimal risk of contamination.

Sterilised grain spawn bags make it possible to produce your own mushroom grain spawn without the use of a pressure cooker.

Who We Are

I’m Luke and I’m mad about mushrooms. I operate a small scale family run business located 40 minutes west of Brisbane. We’re passionate about fungi and we look forwarding to sharing our experiences with you.

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