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Growing Oyster Mushrooms in Truro

Uli Winslow loves oyster mushrooms.

He names some of his for me, “This is an Italian, this is a winter white I believe, these should be King oysters which are pretty cool, a little different than your regular oyster, much more firm.”

If you’ve ever walked in the woods in New England, you’ve probably seen an oyster mushroom, even if you couldn’t name it. They come in a variety of species and colors, but they all look similar—ribbed on the underside and smooth on top and they grow in clusters that form a kind of ruffled, multilayered shelf. It sounds familiar, right? Cooks love oyster mushrooms for their mild, woodsy flavor and in the wild they grow on decaying hardwoods but Uli grows his indoors.

“So they’re all grown on 10-pound sawdust blocks, and they’ll fruit about 2 pounds the first time and maybe another pound or two on second or third flushes.”

We’re standing in Uli’s grow room, which is a roughly 12 by 16 foot space that can produce up to 200 pounds of mushrooms a week. Uli built a homemade humidifier that keeps the room moist and since it’s inside an old greenhouse it’s warmer than the temperature outside, but can still fluctuate with the seasons. Uli says this is important, since different species of oyster mushrooms fruit at different temperatures.

“I’m very much at the whim of mother nature, for sure. You know I have to follow the temperature range of what’s going on outdoors where I can grow 45 degrees up to 85 degrees no problem as long as I have the right varieties growing.”

“They need a little light, yeah, they do absorb vitamin D which is pretty cool, because there are very few foods that can do that. The light just indicates where to grow because the whole purpose of mycelium is to create a mushroom, that then makes a spore to create you know germinate and make another mushroom.”

The presence of light tells the spores they’re not in a hole in the ground and it’s time to start fruiting. In addition to providing a little bit of light, lots of moisture, and the correct temperatures, Uli also has to make sure the oyster mushrooms are on the right growing material—he uses two kinds of pelletized sawdust.

“It’s a mixture of soy, soy hulls which are very nutritious and hardwood oak pellets. They’re actually specifically made for mushroom growers, they didn’t use any lubricants in the milling process of this wood, so therefore there’s no petroleum in there, because mushrooms are amazing at breaking down hydrocarbons they literally use it—use oyster mushrooms specifically to break down oil spills.”

Mushrooms can break down an amazing array of toxins—from boat fuels to PCBs to heavy metals and even plastics. But we don’t really know if the mushrooms that grow out of cleaning up these messes are safe to eat, which is why Uli is so careful about where he gets his sawdust pellets.

And that is what you put in the plastic bags that then turns into this totally different looking substance.

“So mixed, hydrated, add a little bit of lime, just for calcium, it does like a higher pH but the lime is really just adding because they use it for their structure. So here are the bags, they all have a HEPA filter on them so you can do gas exchange of oxygen and CO2 without getting microbes and stuff like that in there.

Uli has to be careful about contamination—if unwanted bacteria or other spores get into his grow bags, they can sometimes ruin a batch of mushrooms. So after he fills the bags with pellets he steams them overnight to effectively pasteurize everything inside. Then he adds the mycelium and lets them incubate for 2-3 weeks before moving the bags back to the fruiting room where it’s warm and moist.

Yeah so I mean all those blocks you see there all those nice are ready to pick, two pounders, I must have put those in here about a week ago today. So it’s pretty quick. I mean I can come in here in the morning and they look different than they did the night before.”

It’s amazing how quickly mushrooms can grow with the right conditions and how tasty they are. I love oyster mushrooms in a simple pasta dish sautéed with garlic, a little bit of thyme, and a whole lot of olive oil and butter.

Here's a link to learn more about different oyster mushroom varieties.

An avid locavore, Elspeth lives in Wellfleet and writes a blog about food. Elspeth is constantly exploring the Cape, Islands, and South Coast and all our farmer's markets to find out what's good, what's growing and what to do with it. Her Local Food Report airs Thursdays at 8:30 on Morning Edition and 5:45pm on All Things Considered, as well as Saturday mornings at 9:30.