How to use grain spawn

Too Much… Too Little?

We are often asked by our hobbyist friends how to properly use the grain spawn they get from MushroomHobby. How does one maximize the use of grain spawn?

Clearly, we don’t want to use too little, because the substrate will take a very long time to get colonized and may even get contaminated. The reason why it can get contaminated is because, by not putting enough grain spawn, you are giving contaminants in the straw more time to take over the substrate. Obviously, we don’t want to use too much because we’re just wasting.

Truthfully, there is no exact science behind this. As we have said before in many of our blogs, the beauty of this hobby is that almost everything is debatable and a matter of personal preference. The decision on how much spawn you should use will be up to you. We only provide a guideline on what works best for us. Even so, allow us to share how we use spawn at MushroomHobby and what works for us.

We didn’t just come up with this recipe one day. We did some research and contacted some of the top hobbyists we know who have been in this hobby for a very long time in Canada and in the US. Then we concluded that the recipe we use is very close, if not identical, to what long time hobbyists use. That’s how we knew that our method of using our spawn to produce mushrooms is not far from optimal and a good starting point for any hobbyist.

There are two easy rules to keep in mind:

– If our substrate has been pasteurized, we go with more or less 10% inoculation rate.
– If our substrate has been sterilized, we go with 5% to 10 % inoculation rate.

What does this mean?

So, let’s suppose we want to make a bag of straw. Straw is pasteurized, so we will be using the first rule that states, “If our substrate has been pasteurized we go with more or less 10% inoculation rate“. This means with every 1kg grain spawn bag, we can inoculate 10kg of Straw. Now nothing stops you from using only 5%, but as we explained earlier, you may end up with contamination because it will take longer for mycelium to take over the bag, which will give more time for contamination to take hold of the substrate. We are not saying it will happen every single time, but the chances of it happening are greater with less spawn used.

Using 10% allows your mycelium to get an advantage over contamination; the power is in numbers! Using more than 10% is just wasting spawn.

In the case of HWFP (sterilized substrate), we will go with our second rule that states “If our substrate has been sterilized we go with 5% to 10 % inoculation rate“. Going below 5% will still work, but then it may take a very long time for mycelium to colonize the entire bag. In our case, we still go with 10% simply to accelerate colonization of our substrate, because we need the substrate quickly in order to run tests. When we grow for consumption, we are more patient and use only 5% spawn. The math behind this is that with 1kg of spawn at 5% rate, we can inoculate 20kg of substrate.

Please see our other blogs covering more specific subjects about the fun world of growing mushrooms.