Two carloads of Local Foods employees hit the road on a pleasant day in early May to River Valley Ranch, located in Burlington, WI. Our first stop was the farm store, established shortly after the farm began in the late 70’s. We perused shelves filled with local produce, unique dried goods, and samples of River Valley’s signature dips and sauces, made right on the farm.

Established in 1976 by Bill Rose, River Valley Ranch has seen many ups and downs. Some moments were wonderful, and some were tragic. Read more on that history on their site.

After perusing the store for a bit, we met Eric Rose, current owner and son of Bill, who led us on a tour of the facility. The mushrooms are grown in a series of arched-roof buildings connected by a long hallway on one end.

It all begins, as most things do, with compost. A mix of manure, straw and minerals creates a fertile foundation.

River Valley is working on a new composting structure, which includes slats below that allow for air to flow through the compost. This simple change speeds the rate at which compost reaches peak conditions for being transferred.

If you jumped into this compost heap, you would want to quickly escape, as temperatures inside reach 180° Fahrenheit. The bacteria in the manure consumes the sugars from the hay in a process Eric described as “caramelizing” — which essentially pasteurizes the compost. It’s good for sniffing.

When the compost is ready, mycelium, a sort of “rootstock” for mushrooms, is introduced and mixed in. Large beds are then filled with the compost and mycelium mixture, then stored in high-temperature rooms where the mycelium colonizes the compost and sets the stage for mushroom growth.

The beds are then moved into the long buildings, where cool temperatures and high humidity encourage mushroom growth. Harvesters then work their way through the beds each day, picking right-size mushrooms at a rate of about 15,000 lb per week. Remarkably, the room pictured below goes through a full cycle of “first flush” growth through the end of its life cycle in less than 3 weeks.

Beds of cremini mushrooms growing at River Valley in Burlington, WI

Here’s an interesting story from the farm’s history: they started growing portobellos completely by accident! One day in the middle of the summer of 1990, the AC unit used to cool the cremini mushroom house shut down. Cremini mushrooms are actually baby versions of portobellos – and when the AC cut out, mushroom growth accelerated quickly. Instead of throwing away the giant mushrooms, Eric took them to the farmers’ market. After landing a spot in the newspaper, sales picked up, and he’s never looked back!

We’re proud to work with River Valley! If you have any questions about mushrooms or how they’re grown, give me a shout.

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