MycoCosm Mushrooms

By Gregory Daurer | Dec 13, 2021

Company Details


Broomfield, Colorado



Ownership Type





Culinary mushrooms

Founder Justin Killing sells gourmet mushrooms to customers at farmers markets and restaurants while trumpeting the many benefits of fungi.

Photos Jonathan Castner

The mushrooms that Killing cultivates are so colorful that he says, "Sometimes when we go into our grow rooms, I feel like I'm going snorkeling, like I'm [swimming past] a coral reef or something." There are beige shiitakes, creamy-white lion's mane, and, especially, a host of multi-hued oyster mushrooms that come in varieties like blue, pink, and golden. The Black Pearls have white stems and dark caps.

When he sells his MycoCosm Mushrooms at the Boulder County Farmers Market, Killing has heard comments about them like, "It looks like a bouquet of flowers!" Or, "Wow, these are gorgeous!" But, despite people's obvious attraction to the delicacies, inevitably the most common reaction he gets is, "I have no idea what to do with them" in terms of preparation and cooking.

So, Killing will suggest, for example, crisping up pink oyster mushrooms, which take on a flavor similar to bacon. Customers will return and tell him, "I didn't believe you, but you were right!" Or he'll suggest shredding the spongy lion's mane, then roasting it, before turning it into vegetarian crab cakes. Killing has had people from places like Maine say to him afterwards, "You can't tell anyone I ever said this, but that was better than New England crab cake!"

About a dozen restaurants have figured out what to do with Killing's mushrooms, purchasing them from him on a regular basis. At River and Woods in Boulder, they smoke blue oyster mushrooms and serve them as a side. Ash'Kara gives MycoCosm a shout-out on its menu within the text for its nosh of "grilled mushrooms + fingerlings." Leaf Vegetarian Restaurant offers a Calamari Style Oyster Mushroom small dish.

Since founding his mushroom cultivation operation in March 2020, business for Killing has been (here comes the obligatory cliché) mushrooming. In terms of output, he says, "We're doing between 400 and 500 pounds a week."

The mushrooms are grown within the 2,700 square feet of space Killing leases in Broomfield. There, he prepares the substrate material consisting of "combos of grains, hard-woods sawdust, different admixtures, organic soybean shells." He hydrates the substrate, sterilizes it, then introduces tissue culture into it, belonging to whichever mushroom strain he wants to grow. In sterilized grow chambers, the mushrooms mature within anywhere from -- depending on the species -- two weeks to four months. And, although they're being grown indoors, Killing still cultivates them during the season the strains naturally grow. In total, he vends a dozen different varieties.

In addition to telling people how mushrooms can be prepared to be eaten, Killing also likes to point out the medicinal qualities of certain varieties. He says of shiitakes, "They're absolutely incredible in terms of boosting your immune system" and "a general aid to vitality." Lion's mane mushrooms potentially boost the brain's development of myelin, which "helps you learn and remember things more effectively." Reishi has also been long prized in Chinese medicine for its "incredible immune-boosting" properties. Killing has begun powdering mushrooms like lion's mane to be used within value-added products like infused honey.

Furthermore, mushrooms can be used in environmental remediation in order to pull toxic chemicals out of the soil, and Killing has participated in projects related to that work when he lived in Olympia, Washington. At Evergreen State College, he studied "ecological science, with a focus in permaculture design and mycology." Due, in part, to nearby forests in which to forage for mushrooms -- and to the nearby presence of popular mycologist Paul Stamets and his company, Fungi Perfecti -- Killing says of Olympia, "You couldn't ask for a better environment in which to study mushrooms."

Killing, who grew up in Colorado Springs, returned to Colorado in 2016. Prior to starting his company he worked a sales job in the solar industry, which "while purposeful, wasn't that much fun."

But growing mushrooms? "I love it!" he says. Killing was growing mushrooms as a personal pursuit when a neighbor who runs a food business began introducing Killing to local chefs. They began placing orders with him, and Killing's business "just grew and grew -- and grew fast!" Soon his house near Boulder was half-filled with his cultivation operation, necessitating the relocation of his business to a more suitable space in Broomfield.

Eventually, Killing wants to purchase a spread of land on which to grow mushrooms, using the compost material to help rebuild soil -- which Killing has learned, through his studies in permaculture and mycology, mycelium facilitates. "We have 60 years of topsoil left on this planet at the current rate of consumption and that's only set to increase," says Killing. "Mushrooms are one of the most efficient ways to rebuild soil health on earth."

There's another point Killing likes to make about mushrooms: they're closer to humans than they are to plants. Unlike plants, mushrooms breathe oxygen and release carbon dioxide. "Mushrooms are heavily constructed of chitin -- like our fingernails," Killing notes. And, from his own observation, they don't like to be overcrowded -- just like human beings: "I like to walk into one of our spaces and feel like I want to hang out in there -- because if I feel good in there, they probably feel good in there, too."

Killing says of his profession, "Getting to interact with a dynamic, living organism that has its own kind of personality, if you will, and working with the cycles and changes of seasons and temperature and all these things, it's kind of like a mixture of art and science. So, I find it very gratifying."

Challenges: "It's been a challenge for me operating in a metropolitan environment, because I'm a permaculturalist at heart," says Killing. Presently, he offers local farmers the compostable material from his indoor grow.

Opportunities: Killing says, "Using this as a platform to educate and develop better systems so we can live more harmoniously on earth." The name of Killing's business is a play on the word "microcosm" which translates as "little world" from Greek, according to Merriam-Webster online dictionary. Hence, "MycoCosm" indicates a "mushroom or fungi world."

Needs: "Traditionally, this bioregion couldn't support the amount of humans that are here. The way that we've done that is through outsourcing and shipping and receiving all the goods that substantiate life here from other places," says Killing. "I think we have the opportunity to create ingenuitive, bioregional food systems, [so] we don't have to depend on shipping and oil and gas to import all of this stuff."

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