The Dirt on Mushrooms

Have you ever wondered about those little specks of dirt on the surface of mushrooms? You’re not alone! The process of growing mushrooms has intrigued people for ages, leading to misconceptions about their cultivation (ahem, like being grown in manure) and the mysterious dirt-like particles. Today, we’re shedding some light on this fascinating topic and uncovering the truth behind those seemingly inconspicuous specks. So, let’s dive into the world of cultivated Canadian mushrooms and explore the journey from the growing rooms to your plate!

The Peat Moss Mystery

It’s time to debunk the myth! That “dirt” on mushrooms is most often peat moss, and it plays a crucial role in the mushroom growing process. Canadian mushroom growers utilize peat moss as the “casing layer,” covering the top of the mushroom beds. But what are these beds, and how does it all work? Read on….

The Mushroom Growing Process

Mushrooms are grown in beds within large growing rooms. Before each crop is “planted,” the rooms and beds undergo a thorough sterilization process at a temperature of 160°F (71°C) for 24 hours. This ensures a clean environment to begin mushroom cultivation.

The Substrate and Spawn

Once sterilized, the beds are filled with a growth medium called substrate, which provides essential carbon and nitrogen nutrients for the mushrooms. The substrate is pasteurized at 136°F (58°C) for 8 hours before the mushroom “spawn” is mixed into it. Spawn is essentially mushroom mycelia attached to sterile grain, acting as the seedstock for the mushrooms. It is delivered to the grower in sealed bags from specialized laboratories that focus on mushroom mycelia genetics.

The Casing Layer: Enter Peat Moss

As the substrate layer reaches a thickness of about 8 inches (20 cm) in the beds, a 2-inch (5 cm) layer of peat moss is spread over it. This layer is known as the “casing layer” and serves to provide necessary moisture for the mushrooms to flourish. The mushroom mycelium permeate throughout the substrate and emerge through the casing layer, forming the mushrooms on the surface of the peat moss.

The Magic of Mushroom Growth

The growing process is a dance of precise control! The grower regulates temperature, humidity, oxygen, and CO2 to stimulate the mushroom mycelium to develop mushrooms on the surface of the peat moss. This process takes approximately 15 days from spawning to harvest, resulting in those beautifully grown mushrooms you find at your grocery store.

Removing the “Dirt” Specks: A Simple Rinse

Now that the mystery is solved, what’s the best way to remove those peat moss “dirt” specks? It’s remarkably simple! Just give the mushrooms a quick rinse under cold running water and pat them dry just before you enjoy them. Voilà! Your mushrooms are ready to take their rightful place in your favorite dishes, enhancing their flavors without any extra effort.