Inside Rock City Mushrooms: A Tour of Underground Fungi Cultivation
Ever wondered what goes on behind the scenes at a mushroom farm? Join us as we take a fascinating tour of Rock City Mushrooms with owner Ben, who shows us how they grow an impressive 400 pounds of gourmet mushrooms weekly in their underground operation.
Welcome to Mushroom Land
“This is Rock City Mushrooms. Everything in the basement is mushroom land,” Ben explains as we begin our tour. But mushrooms are just one part of their whole farm system, which also includes grass-fed beef, pastured turkeys, and hens for eggs. In true sustainable fashion, all of their composted mushroom substrates eventually feed their vegetable patches.
From Delivery to Cooling
Rock City Mushrooms sources their substrate blocks from Maine Cap and Stem, a supplier Ben speaks highly of. Every two weeks, they receive a shipment of around 140-160 blocks per pallet, with multiple pallets arriving at once.
“We’re trying to do a two-week cycle,” Ben explains. “We go through half of the shipment every week, and the stuff holds up pretty well.”
After delivery, the blocks head straight to the walk-in cooler—a tight 10′ x 15′ space that uses a Cool Bot system with an AC unit. The cooler gets particularly crowded on Tuesdays when it also stores CSA items. Even in the cooler, some blocks might start to fruit if they’ve been stored for too long, so Ben adjusts their schedule accordingly.
Into the Grow Room
When it’s time to fruit the mushrooms, the team packs everything from the cooler onto metal racks with wheels that can be rolled directly into the fruiting room.
“Welcome to the grow room,” Ben says as we enter. Rock City grows three main varieties: shiitake, oyster mushrooms (in multiple species), and lion’s mane. The room is strategically set up to accommodate each variety’s specific needs.
“This part of the room is super dry—that’s where we keep the shiitake since they like it dry. The lion’s mane get the airflow from the fan, and the oysters are pretty resilient, so they get whatever’s left, though we try to give them a good amount of air.”
The room features an intake fan that brings in outside air, which passes through a humidifier to prevent the blocks nearby from drying out. Ben keeps the humidity in the high 80s to low 90s—high enough for the mushrooms to thrive but not so high that the floor gets wet and slippery. Floor drains help manage any excess moisture.
Lion’s Mane: The Crown Jewel
Ben proudly shows us the lion’s mane mushrooms, which are starting to form impressive clusters. “These will come in nice and big in a line, which makes them really easy to harvest,” he explains.
For lion’s mane, they cut slits at the top of the bags where the mushrooms are already pinning, allowing them to fruit naturally. “It takes less time for them to fruit, and I think it’s just a better flesh,” Ben notes.
After harvesting the first flush, the team flips the blocks and places them vertically on racks, cutting another slit on the opposite side for a second flush. “We get about a pound on the second flush, which is pretty good,” Ben says, compared to the two to three pounds from the first flush.
Interestingly, Ben has noticed that second-flush lion’s mane have “a little less water in them, which make them more tough and meatier. They also get teeth way faster and have more teeth.” He prefers to harvest them right as they’re starting to develop teeth, as their shelf life isn’t as good once the teeth fully form.
Oyster Varieties: Each with Its Own Personality
Rock City grows three kinds of oysters: blue, phoenix (brown), and black. Each variety has its own growing characteristics and harvest techniques.
“The blues we just either cut from the top in a diagonal line or come from the side,” Ben demonstrates. “The phoenix I’m still trying to figure out. Sometimes they grow really nicely with a diagonal cut, and other times they just get kind of weird and grow really tight. I think part of it’s because the room’s been cold, and they’re more of a warm-weather oyster.”
The black oysters are Ben’s favorites. “They’re awesome,” he says enthusiastically. “They’re sometimes mistakenly thought to be a mix between king trumpet and blue oyster, but I don’t think that’s true. They do have that consistency, though—a thick base, big stem, and light cap. Restaurants really love them.”
Each variety has different growth rates: phoenix takes 7-10 days, blues take 9-12 days, and blacks need a full two weeks to fruit after cutting. The harvesting technique varies slightly between varieties, with blues being the easiest to pull off in clusters, while blacks are more brittle and sometimes require cutting.
The Perfect Mushroom?
When asked which species he’d grow if he could only choose one, Ben doesn’t hesitate. “We’ve buffed our production the most with lion’s mane. They take a little longer to grow, but they’re so cool looking and pretty resilient even though they’re slow.”
He appreciates their versatility in the kitchen: “They taste good, you can eat them in a bunch of different ways. I dry them and put them in my coffee. And I don’t really get sick of them—I’ll be honest, sometimes I get a little sick of the blue oyster.”
The black oysters are a close second: “They’re really good, they have a meaty texture, and I think they grow pretty well. I haven’t totally mastered them yet, so it would be cool to really get it down.” He mentions a restaurant that makes deep-fried black oyster “chicken-fried style” with lemon and aioli that’s particularly delicious.
Infrastructure and Climate Control
The underground grow room benefits from natural temperature regulation, with cement walls and floors helping to maintain a consistent environment. “In the winter, it will be low 60s, and in the summer, it can get up to 75, but it’s pretty good to keep it within 10 degrees consistently,” Ben explains.
The room uses standard fluorescent lighting, and they adapt their species mix seasonally. “Part of why I wanted to try to get the phoenix oysters in here more is because I think in the heat they’ll be much better. I’m a little worried about these guys [the other varieties] as stuff starts to get warmer.”
Shelving Systems: Wood vs. Metal
Ben shows us two different types of shelving: wooden racks that have been in use for 3-5 years, and newer metal racks. Each has its pros and cons.
The wooden racks work well for oysters since the blocks don’t sit directly on the wood, preventing erosion. However, they can harbor insects (though Ben welcomes spiders as natural pest control), and their wheels no longer work well.
“What’s really nice about the metal racks is that they have nice wheels. We can stack everything from the cooler and just roll them all into the grow room, which has been awesome,” Ben explains. “They’re also more stable and so easy to clean—we power wash them and sometimes spray them down with isopropyl alcohol.”
The metal racks can fit 10 oyster or lion’s mane blocks per shelf (50 total on a 5-shelf rack), while they limit shiitake to 8 per shelf (40 total) since shiitake fruit all over the block and need more space.
Harvesting Shiitake
As our tour concludes, Ben demonstrates the shiitake harvesting process using a wooden board placed across a crate. He looks for mushrooms with visible gills and a slight curl at the edges.
“This is perfect in my opinion,” he points out. “It’s better to take them earlier than later because when it’s curled under, there’s more protection for the gills, and the gills are usually what bruise first.”
Ben carefully cuts the mushrooms from the block, letting them fall into the crate below. “I try to get as little sawdust on them as possible,” he notes. Unlike the oyster and lion’s mane, shiitake typically produce just one flush, so timing the harvest is crucial.
The warmer the temperature, the faster shiitake grow. “Last week it got really hot, in the 90s. I like to try to take weekends off, so Henry was covering for me, and he said the grow room exploded! He was a champ and got them all done.”
After harvesting, each crate is labeled with the date, species, and weight before heading to the cooler. They’ll cover the crates with a tablecloth to maintain some humidity while preventing the mushrooms from becoming too moist.
As Ben puts it, mushroom farming is “like babysitting a bunch of little brats sometimes. You love them, but they misbehave sometimes and don’t do exactly as you’d like.”
But judging from the beautiful, bountiful harvest we saw on our tour, the team at Rock City Mushrooms has certainly figured out how to raise these delicious fungi right.