30 Sep 2019

Where Does Your Food Come From? Mushrooms

From First Up, 5:45 am on 30 September 2019

Buttons, cups or flats - their strong flavour can divide a crowd and cause arguments at the dinner-table.

But how much does the most avid-mushroom lover know about how their favourite fungus is grown?

Visual Journalist Ana Tovey headed to the Parkvale mushroom farm near Carterton to find out more about mushroom cultivation.

Parkvale Mushroom’s owner Clive Thompson reveals the somewhat fragrant beginnings of his mushrooms. The enormous shed is steaming with compost and he says the temperature gets up to around 80 degrees.

“It’s just all microbes and all doing their job … it’s pretty smelly," he says.

After several weeks of precision-controlled wetting down, turning and curing, the compost is ready for the crucial ingredient – mushroom spawn - kept in a cool room, under lock and key.

“It’s just a grain, we break it up and mix it through the compost … so there’s probably enough spawn here for about 10 weeks I would think.”

He says his interest was piqued when he ventured out as a teenager and saw mushrooms growing, then he read a book about cultivated mushrooms. 

"They intrigued me. So I cut all my parent’s fruit trees down, dug a big hole in their backyard, built a building and started to grow mushrooms. I established Parkvale Mushrooms in 1966 and I’ve been growing them there ever since."

The mushroom farm has been converted from a former dairy factory and spreads across a number of buildings, with alleyways leading to various dark rooms where the mushroom magic happens.

“This is where we grow the spawn, in the compost," Thompson says showing one of the rooms to Ana Tovey. "They’re tightly stacked because it’s just a matter of getting airflow around the boxes to keep the compost temperature around 25-26 degrees Celsius.”

The matured boxes of mycelia are then taken by forklift to a large system of conveyor belts and machinery for a final layer of treatment that's needed to activate the mushrooms.

Once everything is mixed together the workers check the depth of the compost and make sure all the lumps are broken up, then it’s taken to the final room where the mushrooms get to grow.

After another 17 days bedded down in the dark rooms, the mushrooms are ready for picking.

“We’ve got about 14 growing rooms and they [the mushroom pickers] are picking the first flush at the moment, we get four flushes. The first flush is normally about half the production and the next flush gets a bit smaller," Thompson says.

“What they’re doing is they’re going through and picking out the flats mainly, and sometimes they have to thin out some of the buttons to make enough room.

“It’s all electronically controlled but we do monitor psychically the whole crop in each room, every day, twice a day, just to check that everything’s fine. And I would check each night before I go to bed, [to check] that everything’s fine, and the same thing in the morning when I wake up.”

He expects within the next couple of days it’ll yield a couple of tonnes.

Next stop is the packing shed, where the mushrooms are graded and weighed, and sent into the cool room to await collection.

“We’re pretty small really. We’re not the smallest, but we do about seven-and-a-half tonnes a week of mushrooms and we ship our mushrooms all over the North Island.”

But some don’t have far to travel, with nearby Carterton café Wild Oats taking pride in the local product as one of the ingredients in its recipes.

“It keeps everything in your area, it’s all community, so you know where the mushrooms are coming from, you know who the people are when you go to pick them up, little things like that,” café manager Crystal Thompson says.