Growing the perfect mushroom

white mushroomsThey say it’s one of the most difficult crops to grow, second only to orchids. A statement like that probably brings all sorts of exotic plants to mind, but what we’re actually talking about here are mushrooms.

Yes, mushrooms. I was surprised to learn this too, but the comment came from Lyle Whitham, General Manager of Continental Mushrooms, during a recent tour of the Ottawa region farm. And if anyone knows a thing or two about mushrooms, it’s Lyle, who has spent most of his life involved in the family business.

Continental Mushrooms, one of Canada’s largest mushroom growers, was founded in 1972 and now produces about 200,000 pounds of mushrooms every week for customers across Ontario, Quebec and the Maritimes.

making compostGrowing a good mushroom is a fairly exacting science, as we learned from Lyle during our tour, and at Continental, it all starts with the making of just the right compost.

“We need a good, smelly start,” laughs Lyle as he explains that Lyle with compostalthough it smells like manure, there’s actually no manure in the compost. It takes three weeks for the mixture of hay, straw, corn, cocoa bean shells and other materials to turn into the compost they use to grow their mushrooms and they produce 500 tons of it every week to keep their production going continuously.

The compost is monitored constantly during the production process to make sure it’s developing properly. It is then pasteurized to kill off any potential pathogens before the mushroom spawn is blended in as the mixture goes into the mushroom house.

From the time the compost enters the house, it takes 30 days before the first mushroom can be harvested. Each “break” or batch of mushrooms that can be harvested lasts about a week with one production cycle yielding three breaks.

“We have eight weeks of production for three weeks of harvest,” says Lyle. “Of course, the quality is best at the first break.”

Once harvest is over, each room is emptied of used compost and steamed thoroughly before the next production cycle begins. The mushrooms take out of the compost what they need to grow but the spent or used material still has all the ingredients necessary for photosynthesis so it is sold to gardeners.

brown mushroomsAt Continental, the main crop is white mushrooms, although they also grow some creminis. In order to maximize production, each species of mushrooms requires its own particular growing conditions that are carefully controlled by staff.

Each mushroom house or growing chamber at Continental can hold a 12 bed high stack. There are 34 chambers on the farm. All the mushrooms are harvested by hand and workers are paid by the amount they harvest.

sliced packaged mushroomsOnce harvested, the best mushrooms are sold on the fresh market. Continental also sells both whole and sliced mushrooms into food service for use in restaurants and institutional settings.

“It’s harder to sell mushrooms at retail because customers expect a beautiful, fresh product,” says Lyle. “At a restaurant, customers don’t see the mushroom until it’s cooked and served.”

A batch of fresh mushrooms will bring $1.60/lb on the fresh market the first day of harvest. By the third day, that same batch is only worth about $0.32/lb from a cannery.

The world of mushroom growing is a relatively small one and it’s not an easy business to get into.

“There’s still an art form to growing mushrooms well,” says Lyle. “You pretty much have to develop your own people from within because there’s not really any place you can go to learn this stuff.”

continental boxTo learn more about Continental Mushrooms, including mushroom recipes and funky mushroom facts, visit

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