Growing Oyster Mushrooms: A Timeline

Parks at Home for Grownups

At Glenwood Gardens, I experimented this summer with growing oyster mushrooms. Oyster mushrooms (Pleurotus ostreatus) are great for beginners because they aren’t as fussy about temperature and humidity conditions as many other mushroom types.

Left: Cardboard and pieces of mycelium from the mushroom starting kit. Right: A bin full of cardboard and mycelium starts. (Photos: Ellen Meehan)

I started the mushrooms on July 8. I used a mushroom growing kit, cardboard boxes cut into strips, and an egg crate. I broke the mycelium (the root-like structure of a fungus) in the mushroom kit into pieces and soaked the cardboard in boiling water. Then cardboard and mycelium pieces where layered inside the egg crate.

Oyster mushroom mycelium growth after one week. The mycelium completely covers cardboard in an egg crate.
The actively growing mycelium after one week in the egg crate. (Photo: Ellen Meehan)

I placed the egg crate inside a large plastic box to keep in moisture. After one week, the whole container smelled like mushrooms and the mycelium was actively growing.

Mycelium of oyster mushrooms begin to cover shredded pieces of cardboard.
Two-week growth of mycelium. (Photo: Ellen Meehan)

After two weeks, the mycelium had completely covered the cardboard and the egg crate was ready to move into an area with airflow and indirect sunlight. Oyster mushrooms need airflow and indirect sunlight to form the fruiting bodies, which is the part of the mushroom we eat.

Left: Pins (or baby mushrooms) began growing in the egg crate. Right: The oyster mushrooms were full sized and ready to harvest five days later! (Photos: Ellen Meehan)

After removal from the bin, I misted the egg crate regularly to help keep it moist. Probably due to the unusually warm weather in July and August, it took four weeks instead of the more typical three for the mushrooms to start growing. Oyster mushrooms prefer a temperature of 70 F to 80 F, and the highs were mostly in the 90s during the time they were growing.

Five days later, the mushroom were full sized and ready to harvest!

Three plastic bottles show mycelium growing in different substrates. From left to right, the bottles have substrates of cocoa peat, recycled newspaper pellets, and aspen mulch.
From left to right, the bottles have substrates of cocoa peat, recycled newspaper pellets and aspen mulch. (Photo: Ellen Meehan)

Over the next month, the mycelium put out two more flushes (or sets) of mushroom growth. By the third flush, most of the nutrients are used out of the substrate and new growing substrate is needed. This time I decided to do a little experiment. I used cocoa peat, recycled newspaper pellets and aspen mulch as the substrate to grow the mushrooms on. My containers this time round were clean plastic drink bottles. I chose these instead of the egg crate to help keep the substrate moister. I had problems the first time keeping the cardboard moist, probably due to the number of holes in the egg crate. I took a piece of cardboard from the egg crate set up and buried in in the new substrate. About 10 days later, the mycelium is starting to spread and grow.

If you would like to see which one of these bottles grows the most mushrooms, come visit us at Highfield Discovery Garden.

Ellen Meehan
Nature Interpreter, Glenwood Gardens