Growing with the Bag Method

Transitioning to growing using the bag method didn't seem to be too difficult. When I watched videos of Southwest Mushrooms or other YouTube channels implementing the method, it seemed simple enough. You sterilize the substrate then pour in the grain spawn and close the bag. What could go wrong?

However, over the past three weeks, I realized that I have been making a number of mistakes some minor and others major. Below, I will list seven mistakes that I had made for the first batches.

1 - Improper hydration

It is commonly recommended that the masters mix substrate is hydrated to around 60-65% water. I initially thought of bakers percentages and added 60% of the dry weight in water, meaning that the actual hydration was closer to 30% of the total weight. On the batches with improper hydration, the mycelium seems to have stalled out in the colonization process after about ~3 weeks due to a lack of moisture. The remaining substrate seems dry and it is unlikely that it can be colonized fully

2 - Improper laboratory settings

In the absence of a laminar flow hood, I did inoculations without any air sterilizing technique, hoping that it would turn out well. Since I am cultivating oyster mushrooms I'm not sure that this is absolutely necessary - due to how aggressive they are - but I have since purchased and set up a laminar flow hood. I still do not have a designated sealed off laboratory with positive air pressure but having the laminar flow hood is better than nothing

3 - Improper lab procedures

In the beginning, when doing inoculations, I did not give much thought to wearing specific clothing, masks, gloves, and sterilizing equipment. I have since then decided to maintain the following procedures whenever I do inoculations: (1) wear a mask - breathing can expel bacteria found in one's mouth which can contaminate the substrate, (2) wear fresh disposable gloves and wipe gloves with isopropyl alcohol at beginning and in between inoculations, (3) sanitize workspace with alcohol before inoculations, (4) sanite scalpel blade in alcohol flame lamp before using to cut open grain spawn. (5) sanitize workspace with alcohol after procedure completion to suppress any post operation bacterial propagation.

4 - Lack of impulse sealer

I had been sealing the bags with tape which often left gaps, potentially letting contaminated air flow in post inoculation. The impulse sealer properly seals off the mouth of the bag only allowing air-exchange through the 0.5 micron holes in the bags.

5 - Not properly letting sterilized bags cool

Mycelium on grain spawn should not be introduced into substrate until the bags have been allowed to cool to room temperature! Even slightly elevated temperatures can hinder or kill mycelial growth! This is a major mistake that I did not realize I was making for the first few batches. This alone could be the explanation for the slow colonization of my mycelium in the growing bags. Now, I have decided to let any bags sterilized to cool to the next morning at which point I can do inoculations all at once. I don't have a sterile lab to let bags cool in but am leaving them under my 4 ft wide laminar flow hood which will ensure that only clean air is passing around them.

6 - Not properly shaking grain spawn.

When inoculating sawdust substrate, the grain spawn should be even distributed throughout the substrate so as to create more starting points for colonization. If all grain is only on top, colonization will only take place from the topside, slowing the process significantly. Once the bags have been sealed with an impulse heater, they should be shaken thoroughly to ensure that the grain spawn is evenly distributed throughout the bag.

7 - Improper procedures with grain spawn

The instructions for maintaining grain spawn says that the top bag fold should be unfolded to let the micron filter patch allow fresh exchange. I had not been doing this formerly. Also, the grain spawn should be used sooner than later to allow for more vigorous mycelial growth. Finally, when the grain spawn is opened, it is ideal for all of it to be used at once. If it is opened, then stored as an opened bag, there is a chance that contaminants enter the bag.

Conclusion

Given all the above, the fact that my lions mane and oyster mushrooms were colonizing at all might be surprising! After fixing for all the above problems, I would expect the colonization period to better match the 10 - 14 expected period given by most growers online. If I still experience slow colonization, I'm not sure what I would do next. I could bump up the ratio of grain spawn to substrate, but I guess I'll cross that bridge when I get there.