A Mushroom Farm in Every Closet?

A different kind of urban garden may be the key to feeding ourselves locally

Paul Greenberg
4 min readApr 1, 2022


“Oyster Mushroom (Pleurotus ostreatus)” by Martin Cooper Ipswich is marked with CC BY 2.0. To view the terms, visit https://creativecommons.org/licenses/by/2.0/?ref=openverse

Let’s talk about mushrooms.

I’ve been comparing their underground stealthiness to Russian democracy, describing how they grow out of sight, keeping their peace until the right moment. I’ve pointed out that you never do know when they’re going to burst into the light and turn the world upside down.

But this week I want to stop with the metaphors and talk about actual mushrooms and how we might come to welcome them into our cities. I want to go beyond the pie-in-the-sky dreams of growing salads in our skyscrapers that some urban ecologists have proposed. No, I want to propose a much more, ok, underground idea that is no less soaring in its ambitions.

I want us all to start mushroom farms in our closets.

To be fair, I’ve tried and failed at mushroom farming before. As someone who is always looking for new ways of expanding the output of my Ground Zero Garden, mushrooms have forever been the next thing I’ll try. Oyster mushrooms grow well in used coffee grounds and I’ve often thought that I could rescue the spent grounds from coffee shops in my neighborhood and coax them to bear new life. In pursuit of this vision, I gathered a month’s worth of grounds, ordered some spores, and followed the steps laid out online: sterilize, contain, inoculate. I sat back and perused recipes for the mushroom risotto I expected to enjoy in the coming days.

It would require roughly 1.5 million square feet to grow every mushroom consumed in the city. That’s about 50% of the Empire State Building. Not entirely unattainable.

I was unsure how exactly I would know if it was working. I waited. I examined my bags of grounds. I hoped for the famous bursting forth phenomena that mushroom growers brag about. But it never happened. Just a bluish mold. And then…nothing.

What was I doing wrong? It seemed odd that an organism capable of growing at random on a fallen log in the woods or from a moist crack in the bathroom floor could elude me in such a precisely monitored environment.



Paul Greenberg

New York Times bestselling author of Four Fish as well as The Climate Diet and Goodbye Phone, Hello World paulgreenberg.org

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