Mycelium and microcontrollers. COVID educational reflection.

David (drbh) Holtz
3 min readJul 12, 2020


During quarantine I became compelled to learn more about the natural world. I’d been suck in my fictions world of 1s and 0s for so long — that when COVID-19 hit it was a not so gentle reminder of mother nature’s power.

Along with everyday life, my educational energies shifted. Moving away from computers, programming, information theory, math and towards things I could touch; like plants and animals.

My Google searches were full of Latin names for plants, symbiotic species, how to grow one radish ?— how to grow 1000? New topics require deciphering, I didn’t know which “hardiness zone” I lived in. I didn’t know the importance of good soil or much about the trees outside my window.

In hopes to defeat this monster of unknown, I setup experiments and watched a lot of YouTube. *when looking for information for code, written documentation is almost always better then any live example, but with physical things nothing substitutes actually seeing the process.

One organism really piqued my interest, mycelium. The attributes of this particular organism seemed to 1. Be very unique and 2. Lend itself to automation.

Mycelium for those who don’t know (everyone I talk to) is the body of fungi. It’s fruit is what we are familiar with; mushrooms.

Fungi is a fascinating creature— it grows on decomposing organic material. That material is generally wood or some other vegetative material and is why you’ll usually find mushrooms along the base of fallen trees or damp wooded areas.

Mushrooms are the umbrella name for thousands of unique species that are widely consumed for culinary and medicinal reasons. While western cultures are adopting the benefits of this organism at a slower rate then many eastern cultures — the US still imports >$120 million of mushrooms a year and the total us mushroom market accounts for about $1.8 billion a year.

So why’s this matter — we’ll because with this new “free time”, I thought it would be an interesting crop to grow. It scales well, has great margins and surround a mysterious organism that has proven to be useful in wide ranging things like cancer treatment, economical house building and even “vegan” leather.

The thought process here; is that if I were to grow and learn about something it should be profitable economically and humanly.

So just to get started I order a simple mushroom growing kit. The kit arrived and my girlfriend and I followed the instructions — watering and checking our oyster mushrooms every day. About a week later we saw out first mushrooms sprout — and they continued to grow at an amazing exponential rate. A way more satisfying lifecycle than my vegetables slowly peaking out from the dirt.

Awesome. We’ve identified a great crop — we’ve grown it and eaten it. Now how do we take this to the next level. Buying more grow kits is far from economically practical and also skips many steps of the process. I needed a end-to-end plan.

On reading more about mushrooms I realized that in order to grow them at any commercial scale I would need to create a large environment that is suitable for mushrooms to grow. This environment needs to keep a relatively stable temperature and humidity, it must recycle the are to keep co2 low and allow some light.

I looked online for items to construct this environment and realized it would be expensive and need a couple of disjoint processes. Reviewing the things I needed to control — I decided that building the entire system would 1. Be more cohesive and controllable, 2. Be way more fun.

I knew decision would uncover many new challenges but in the long term I’d have a fully customized system and something that would be built to be low cost and repeatable.

In a following article I’ll cover the technical implementation and iterations of the climate control system. Well looks then the microcontroller, 3volt 5volt and 120volt power systems, and things I learned about electricity and programming