Growing Oyster Mushrooms

Matt Heidrich with some of his home-grown oyster mushrooms 

Matt Heidrich is a man who loves oyster mushrooms.  He enjoys them so much that he has learned the intricate art of home cultivation.  I didn’t know what to expect when I visited him in his Highland Park home, but I certainly got a full tutorial.

Oyster mushrooms are a variety of mushroom that grows on old and dying trees throughout the nation.  They grow from the sides of trees with their gills that slope down to meet the stem.  The caps range from cream to dark brown. They are one of the simplest mushrooms to cultivate, and enjoyed by mushroom enthusiasts and foodies alike.  I always assumed they were called oyster mushrooms because the flavor (to me) is very much like oysters, though some say the name derived from the shape of the mushroom’s cap being similar to an oyster shell.

A child of Army parents, Heidrich spent his childhood in Indiana, and it was there that he first found and harvested some of another wild mushroom in the woods – the popular and colorful chicken-of-the-woods. 

In 2015 at Los Angeles’ eclectic EcoVillage, he attended a workshop led by Peter McCoy where he was introduced to the lifestyle of fungi. The workshop included the details for cultivating the oyster mushroom, and Heidrich was hooked.  Over the last several years, he has refined and perfected his technique for producing oyster mushrooms in his home. 

When I first visited Heidrich, I was given a tour of his small backyard, where he grows numerous herbs and vegetables in small upraised beds.  In one corner was a small compost pile covered with black plastic, which he uses mostly for the old medium of which his mushrooms grow.  He pulled up a corner to show me that oyster mushrooms abundantly grew from his little compost pile, the unexpected result from the leftovers of his cultivation.  He picked a few of the good ones for his meal later in the day.

Next, we went indoors for the tutorial.  It was quickly evident that growing oyster mushrooms were important to Heidrich, because it appeared that major portions of at least two rooms in his home were devoted to the various stages of oyster mushroom cultivation. 

We began by looking at some of the good textbooks that are available on the subject. Two of the best current books on mushroom cultivation are “Growing Gourmet and Medicinal Mushrooms” by Paul Stamets, and “The Mushroom Cultivator” by Stamets and Chilton.   "Radical Mycology" by Peter McCoy and "Organic Mushroom Farming and Mycoremediation" by Trad Cotter are also very useful.  And for those who want to buy starter kits, Stamets' company, called FungiPerfecti, provides supplies for beginner and expert alike.

There are many ways to cultivate mushrooms.   Understanding the difference between "spores" and "spawn" is key.  Spores are genetically diverse "seeds" that rain down from the gills of the mushroom.  The novice grower will not use spores, but spawn, which is genetically identical to the parent mushroom.  Most home growers use liquid culture spawn and grain spawn.  Liquid culture is simply mushrooms grown in sugar water.  Grain spawn is mushrooms grown on grain.  Heidrich cultivates his liquid culture using simple sugars purchased from the local homebrew shop.  (In fact, homebrewing and mushroom growing go hand in hand.)  For grain spawn, he uses organic wheat berries bought in bulk on Amazon.  The goals of these methods is to give the mycelium (the mushroom body) the nutrients it needs to form robust fruiting bodies (“fruiting bodies” are what most of us simply call mushrooms).  Liquid culture and grain spawn are readily available on Ebay or from mushroom websites.  The simplest way to begin cultivating is to buy liquid culture online and expand it at home in modified Mason jars.  But cleanliness is key.  

Heidrich created his own sterile environment with a 5 gallon clear Rubbermaid tub, onto which he has added two hole where his hands can enter with gloves.  Into this box, after has disinfected it with alcohol, he adds the starter medium, and several Mason jars of wheat berries which will be inoculated with the liquid starter medium. 

He carefully closes the lid of the box, and once everything needed is inside the box, he dons his gloves and his hands enter the box.  The lid of each jar has had two holes drill into it: one hole is stuffed with cotton for aeration, and the other is filled with high temperature RTV engine silicone.  With a hypodermic needle, he first sucks a measured amount of the liquid out of the starter medium, by pushing the needle through the silicone cover, and then he injects a measured amount into each jar of the wheat berries, again, by pushing the needle through the silicon layer.

This is all done very carefully, almost like a careful dance as Heidrich maneuvers into the limited space. But all this is necessary, otherwise the invisible contaminants in the air and environment which will infect the batch of mushrooms.

When done, Heidrich places these inoculated bottles of wheat berries onto a rack with an LED light to assist in stimulating the grown of the spawn. Temperature requirements vary depending on the oyster variety.  For example, there are blue oysters which prefer a cooler temperature, while the pink and phoenix oysters enjoy temperatures up into the 80s and 90s.

After a few weeks, if all went well, the bottles of wheat berries are covered in a white cob-webby material, which is the mycelium which will produce the mushrooms.

Heidrich took such a bottle to show me how he sets up the final stage of cultivation, which can take place in a plastic bag or bucket.  Today he demonstrated in a plastic bag.

Into the approximately gallon-sized plastic bag, he placed a layer of soaked cardboard.  (I had noted earlier that he had a few containers of old cardboard in his back yard, and this is what he uses to grow his mushrooms.). 

“Remember, these mushrooms like to grow on wood, and isn’t that what the cardboard came from?” smiles Heidrich.  He presses a layer of cardboard into the bag, and then adds a layer of used coffee grounds, a free recyclable material from a local coffee house.  Then he added about 5 tablespoons of the wheat berries covered in spawn. Then he added more cardboard, coffee grounds, and more spawn. He continues this way for several layers until the bag is full.  On his last, upper-most layer, he adds only spawn, then cardboard, then spawn.  Heidrich explains that the coffee grounds are most susceptible to infection, and by having no coffee grounds at the top where it is exposed, there is less chance of infection.

Once this is sealed, Heidrich punches a few holes into the bag so that each hole enters the bag at the cardboard.  Once the mushrooms get growing, they will grow out of the holes where they can be easily harvested.  This bag is again put on the shelf with the LED light, and allowed to sit until the mushrooms start to grow.

It all seems like a very mysterious process, but Heidrich is merely controlling in a scientific manner that which occurs naturally in the forest.

Heidrich’s favorite method of preparation is to sautee the mushrooms with his meals.

“How do you preserve the surplus?” I asked him, innocently enough.

“I eat them as quickly as I grow them,” he said smiling.  “There’s never a surplus!” 

Wow! He loves his mushrooms.  Nevertheless, if growers have a surplus, they can be frozen or dehydrated, and dehydration seems to be the preferable choice.

Heidrich has done some wild mushroom hunting on his own, but found that it was less than fruitful.  After all, wild mushrooms arise based on many factors, such as rain, weather, time of year, association of certain trees, humidity, and other factors.  Heidrich did find some turkey tail mushrooms, but generally prefers to grow his own oyster mushrooms. 

He’s not a vegan, vegetarian, macrobiotic enthusiast, or a food faddist of any sort. “Yes, I eat meat,” with a smile that barely concealed a bit a guilt.  He’s a man who loves one of nature’s finest foods, and he’s found a way to have a constantly supply at home.

Heidrich does offer occasional workshops where he takes participants through the various steps involved.  His workshop participants walk home with an instruction sheet, and a bag of spawn to grow at home. For more information, he can be reached at mattheidrich@gmail.com

 [Nyerges continues to teach classes in self-reliance and survival. Go to www.SchoolofSelf-Reliance.com for the Schedule]