Most people have never thought about how mushrooms are actually grown. Unlike vegetables that need soil, sunlight, and outdoor space, specialty mushrooms thrive in carefully controlled indoor environments — and the process is fascinating. At True Mycology, we're building out our growing operation right here on Long Island, and we want to take you inside what that looks like.
Why Grow Mushrooms Indoors?
Mushrooms don't photosynthesize — they don't need sunlight the way plants do. What they need is the right combination of humidity, temperature, airflow, and substrate (the material they grow on). Growing indoors means we can control all of these variables precisely, year-round, regardless of the weather outside.
This is how we can offer fresh lion's mane and oyster mushrooms in January as easily as in July.
The Substrate: What Mushrooms Actually Grow On
Different mushroom species prefer different substrates. Most of the gourmet varieties we grow — lion's mane, oyster mushrooms, king oyster — thrive on hardwood-based substrates: typically a blend of hardwood sawdust, wheat bran, and other nutritional supplements. Maitake also prefers hardwood.
The substrate needs to be sterilized before mushroom cultures are introduced. Sterilization kills off competing molds, bacteria, and other organisms that would otherwise take over before the mushroom mycelium can colonize the substrate. This is typically done with a pressure cooker or an autoclave — a dedicated sterilization vessel — at high heat and pressure for an extended period.
This is one reason we're currently debating whether to invest in a pressure cooker: doing our own grain and substrate sterilization in-house gives us more control over our process and reduces dependency on outside suppliers.
The Grow Tents and Environment
Our current setup uses grow tents, which allow us to create isolated, controlled environments within a larger space. Each tent can be dialed in independently for temperature and humidity, which is ideal when growing different species that have slightly different environmental preferences.
Our lighting is controlled directly from a phone app — this lets us set precise schedules for the amount of light the mushrooms receive, which affects their development. While mushrooms don't photosynthesize, light still acts as an environmental signal that helps trigger pinning (the formation of mushroom fruiting bodies).
The racks inside the tents from Amazon allow us to maximize vertical space, keeping multiple grows at different stages running simultaneously without crowding.
Humidity: The Most Critical Variable
If you had to pick the single most important environmental factor for mushroom cultivation, it would be humidity. Most gourmet mushrooms need high relative humidity — often 85-95% — during fruiting. Too dry and the pins (young mushrooms) dry out and abort before developing. Too wet without adequate airflow and you risk bacterial contamination and disease.
We're currently waiting on our Viviosun humidifier to arrive, which will give us precise humidity control in our tents. Getting this dialed in is one of the most important steps in setting up a reliable growing environment.
The Growing Cycle
A typical specialty mushroom grow follows a predictable cycle. First, colonization: sterilized substrate is inoculated with mushroom mycelium (either from grain spawn or agar cultures) and left in a warm, dark environment to colonize — meaning the mycelium grows throughout the substrate. This can take 2-4 weeks depending on the species.
Once fully colonized, the substrate block is moved to the fruiting environment — the grow tent — where the environmental triggers (humidity, fresh air exchange, and sometimes temperature drop or light exposure) signal the mycelium to start producing mushrooms. Pins form within a few days, and a full flush of mushrooms is typically ready to harvest within 5-10 days after pinning.
Most blocks will produce 2-3 flushes before they're exhausted.
Following the Build
We're documenting our entire setup journey on our TikTok page — from unboxing equipment to the first pin sets to harvest day. If you've ever been curious about how specialty mushrooms are actually grown, follow along. We're showing it all in real time.
Growing your own mushrooms, or just being curious about where your food comes from — either way, we're glad you're here.