The point is to multiply your tissue, at the fastest and easiest rate possible. I will commonly germinate spores, isolate the best colonies, transfer them to another dish and let THAT grow out. Then I will blend the entire contents of the dish with sterile water and either innoculate a liquid culture or draw the liquid up into a large syringe and innoculate bags of pure grain. When that is fully colonized I will either spread the grain out into a container (If I am looking for the perfect fruit), or if I have that, I will use the grain as "spawn", mixing the fully collonized grains into another bulk substrate - shredded straw, sawdust mixtures, shredded newspaper, manure, compost, or other substrate mixtures depending on the type of mushroom. Finally, after THAT has grown out I will case (if the mushroom needs casing - P. Cubensis doesn't - tecnically, but it is far better, Oyster does not need or even much tolerate casing, shaggies must have it, agaricus must as well).
In EVERY case I use a plenum, it is versiatile becaue different mushrooms have different growing parameters.
View attachment 3022829
This is my primary plenum. I am currently working on a variety of oyster that will grow in warm temperatures and eat palm fronds. Palm fronds don't compost very well, no one really knows what to do with palm waste and it is a large problem in certain areas of california and florida. However, if they are chopped up and treated correctly, oyster mushrooms will grow on it. So, what we end up with is one waste stream feeding a choice mushroom and leaving a very good humus behind which is very good for a soil conditioner and is filled with nutrients. There is also a succession of mushrooms - that is, a primary decomposer (like oyster) leaving a perfect substrate for yet another mushroom, after it has finished its growth cycle, so that second succession mushroom is grown on the substrate that is spent for the first species. Finally it will be sold as a top value soil amendment.
So, a waste product that is now simply put in land fills or chopped up and redistributed as mulch - free for the taking, or better, one can be paid to take it away, feeding two mushroom species - worth 3 or 4 dollars a pound, and then leaving humus which is worth 10 dollars for two cubic feet. I have been working on this project for several years now.
My problem is the temperature range of the oyster mushroom. Most oysters grow and fruit in the high 60's and low 70's. This is not the temperature that palm trees grow. I have been subjecting sucessive fruits to higher and higher temps, taking the ones that grow best and then subjecting those to even higher temps.
Anyway, that is the short story of my current projects.