Fine Tuning Substrate for Higher Quality Mushrooms

In an email I had received from Gary, a gentleman running a small but successful mushroom business (Fresh from the Farm Fungus), he had inquired as to what genetics and substrate I was using - in response to an email I had first sent him asking why my yields were not optimal.

I had seemingly fine-tuned the environment (humidity, temp, air flow, lighting) but hadn't put much thought into the substrate on which I was growing the mushrooms.

Actually, I was using a reliable and high yield mix, known as Masters Mix, as first popularized by a man known as TR from his business Earth Angels Mushrooms. This mix was a mix of 50% oak and 50% soyhull (the outer hull of soy which America produces en mass). My original thinking was that using optimal yielding mixes was the best - who doesn't want higher yield? However, I've came to realize that masters mix has two problems: (1) the soyhull is often sprayed with pesticides such as glysophate which undoubtedly makes its way into the mushrooms grown on the medium and (2) the mushrooms expand too quickly due to excess nitrogen resulting in more watery and flimsy caps which don't store as long.

Of course, more growers than not, optimize for yield and the produce is of adequate quality. Fortunately for them, many consumers are uneducated about mushrooms and would never ask what medium the mushrooms are grown on.

As I've come to realize that many of the farmers markets in this area are taken by farms outputting a higher volume of mushrooms, the selling point of my business should be producing higher quality mushrooms and not competing on quantity.

Therefore, I plan on switching to an approximately 85% oak & 15% organic oat bran mix (& ~1% gypsum), which should produce significantly higher quality mushrooms.

I recommend that any mushroom growers seeking to maximize quality move away from soy hull - or at the very least switch to organic soyhull from reputable sources and cut the percentage down from ~%50% to closer to 20% at most. The result of this is that the caps will become noticeably darker; the fruit, noticeably firmer; and the storage life, noticeably longer.

That growing mushrooms on oak logs (or other hardwood) produces arguably higher quality mushrooms should be noted. However, as a small indoor grower, I do not have the space or time to grow them on such substrate.

Straw also receives an honorable mention as a cheap and reliable substrate which is easier to pasteurize (using hydrated lime; google "Northspore straw oyster mushroom bucket tek" for exact method), however, in my opinion it produces mushrooms even flimsier than those grown on masters mix and should be avoided for those seeking to compete on quality and color.