Second Chances

Over the past months, I noticed that my oyster mushroom yields were not as bountiful as they should have been. Under optimal conditions, oyster mushroom fruiting blocks can produce up to 200% of the dry mass in the bag as fruiting mushroom. So a 6 lb block that is ~2 lb of dry substrate could theoretically produce up to 4 lbs of mushroom, which is incredible! This does not occur over just one flush, but rather the course of two to three flushes, which become progressively smaller. So the first flush might produce 1.5 lbs, the second 1lb, the third, 0.5 lbs, etc.

When I first started growing, my flushes for oyster mushrooms were not adequate, so I spent a decent amount of time trouble shooting. The two main factors I was fixated on were (1) sterilizations times and (2) fresh air exchange. I was originally cutting corners by running sterilizers for shorter than their recommended time, and while the oyster mushrooms grew, I quickly realized that reduced yields could be attributable to under sterilization - bacteria or molds could be exhausting the mycelium which could otherwise be growing unobstructed. As for the second point, I reconfigured my air tubing so that I now pull fresh air through my chimney and maintain levels of CO2 PPM typically below 800, which is adequate.

These changes more or less solved the problem of lower yields on the first flush and now my oyster mushrooms produce ~0.8 - 1.3 lb flushes, which is not perfect, but adequate. The problem is that I have been having an abysmally poor second flush with my oyster mushrooms. I can tell because by comparison, the lions mane mushrooms seem to have no problem automatically generating a large second flush, which renders the bags much lighter after two or three progressive harvests. Oyster mushrooms, while extremely aggressive colonizers, are very sensitive to suboptimal fruiting conditions and will speak clearly through reduced quality when factors are not perfect.

After analyzing this problem using GPT/Grok over the past couple days, I came to realize that I was doing a number of things wrong. This is what I should have been doing but was not:

1) Making smaller cuts - I was making large X's across the entire face of one end, which led to dried out substrate after the first harvest. A smaller X will allow the grower to place micropore tape over the X more easily which will allow for better humidity retention and recovery of the block in preparation of the block. Growers such as Southwest Mushrooms seem to be able to get away with larger cuts, but they presumably have better humidity control than I do.

2) Making the cut in the center of the bag instead of at the end. This will allow for a larger first and second flush as the nutrients from the bag are overall at a shorter distance from the fruiting point.

3) When harvesting the mushrooms, cutting the bouquets with scissors or a knife will minimize substrate loss which leads to greater surface area of dryness - although this problem may be reduced given smaller cut size and micropore tape after first harvest, rending this unnecessary

4) The grower should clean out all the dead debris from the harvest site in preparation for the second flush.

5) As mentioned in step 1, the grower should cover the X in micropore so as to minimize humidity loss.

Now here is where things get tricky. According to my research, there are many growers who swear by soaking a block after the first flush to rehydrate the mycelium. By soaking the oyster mushroom blocks for ~12 hours, it reinvigorates the mycelium and will enable the block to produce a second flush almost as large as the first. While this sounds like the optimal path, it produces a few problems that my basement facility is not perfectly equipped to handle.

First, there is obviously more labor involved. After the first flush, I would need to remove all the blocks, and soak them in sealed containers for 12 - 24 hours. The water would ideally be non chlorinated meaning that I would want the chlorine to evaporate from the water over 24 hours. I would need to get a couple large drums to hold water and the more water in the basement, the larger chance of getting some sort of cockroach and pestilence problem. I would also need to add additional piping to get water into the container. Additionally, the plastic bags would likely need to be removed to allow for maximum soaking meaning that I would need to find some sort of other plastic covering.

Now that I write this all out, it does make sense that soaking would be extremely beneficial for the production of a second flush.

However, being the lazy person I am, I wondered whether there was a less messy way to rehydrate the block and thought of possibly injecting the blocks with water using a syringe. GPT seems to think 200 - 400 mL of water should be adequate for a dehydrated block, so what I will do with the next batch of oyster mushrooms is the following:

1) I will perform actions 1 - 5 as listed above but no more than that on ~10 bags

2) I will perform actions 1 - 5 as listed above and soak them for 12 hours on ~10 bags

3) I will perform actions 1 - 5 as listed above and inject them with some water and gypsum as an additional calcium supplement for ~10 bags.

I am greatly optimistic that this will lead to significantly larger second flushes and better yields all around.

Interestingly, I had not really considered the need for additional hydration when growing second and third flushes until this past week when it really dawned on me that my oyster mushrooms had producing really bad second and third flushes (well I never really got to third flushes at all). Most information I consumed through grow guides and YouTube videos seemed not to mention the need for additional hydration and the importance of proper procedure for a high yielding second flush. As ChatGPT told me (likely stolen from some obscure username in a mushroom forum), "The first flush is easy, the second flush is earned."

Let's go earn those second and third flushes!!!!