Celebrating Mushrooms, Farmers, and Watersheds in Kennett Square

By Christina Catanese

“What’s that smell?” I asked, as we got out of the car in front of my friend’s house in Kennett Square, PA.

“Oh, the mushroom compost?” Jaclyn said. “I don’t even smell that anymore.”

It wasn’t an unpleasant smell, but an earthy aroma that permeated the air the same way the culture of mushroom farming pervades this small Pennsylvania town.

Mushrooms are a way of life in Kennett Square.  Often called the Mushroom Capital of the World, mushroom farms in this area of Southeastern Pennsylvania produce the vast majority of mushrooms produced in the United States, outdone only by China in mushroom farming worldwide.  I heard some figures that mushroom farms in Chester County produce over a million pounds of mushrooms a week!

Enjoying a beautiful day in the Kennett Square community

Enjoying a beautiful day in the Kennett Square community

Every year, this proud tradition of mushroom farming is celebrated at the Kennett Square Mushroom Festival.  I attended this year’s festival a few weeks ago, where I expected to and did eat many types and forms of mushrooms (including but not limited to the classic deep fried mushroom balls, the higher brow mushroom gorgonzola hummus, and even cream of mushroom ice cream).

What I didn’t expect was to learn so much about mushroom farming itself, and its role in the health of the watershed of the Delaware River, Red and White Clay Creek, and other local streams.  Part of the festival was an exhibition that walked through the process of growing mushrooms.  It really gave me an appreciation of the amount of work these farmers have to do to grow their crops.

A mushroom farmer harvests white button mushrooms from his exhibition at the Kennett Square Mushroom Festival

A mushroom farmer harvests white button mushrooms from his exhibition at the Kennett Square Mushroom Festival

It all starts with the substrate (the material the mushrooms are grown in), which generally consists of the waste products from other agriculture industries.  This mix of manure, hay, straw, wood chips, cottonseed meal, cocoa shells, and gypsum has to be kept at just the right temperature, pH, and light conditions in indoor mushroom farms, so the right fungi thrive and the wrong ones that could spoil the crop do not.  Once the mushrooms sprouted, I couldn’t believe how fast they grew, sometimes doubling in size in a single day!

After mushrooms are harvested, the substrate material can’t be used for mushroom farming anymore.  As at any farm, this compost can be a source of runoff and enter streams if not managed properly.  Source water protection efforts in the Delaware River Basin identified mushroom farms in the watershed as a partnership opportunity to help reduce nutrient pollution and potential sources of Cryptosporidium, a pathogen often found in manure that may cause disease.  These efforts work with farmers and conservation districts to set up ways to manage this runoff and protect sources of drinking water.

Phase 2 Compost: what the spent mushroom substrate looks like after mushrooms have been harvested and before it comes to your lawn or garden

Phase 2 Compost: what the spent mushroom substrate looks like after mushrooms have been harvested and before it comes to your lawn or garden

With its high capacity to hold water and nutrients, mushroom compost can be used as compost in many applications, like crop and garden fertilization, erosion control, and stormwater management.  Fall is the best time to seed new lawns and fertilize, so if you’re embarking on this process, consider mushroom or other organic soil amendments for your plants.  Like any fertilizer, mushroom compost must be applied appropriately to avoid nutrient pollution.


By the end of the day at the festival, I didn’t notice the smell of the mushroom compost much anymore, either.  When I did catch a whiff, it reminded me that this compost (like the mushroom ice cream I ate) was just one stage of a much larger process of mushroom farming.  It wasn’t the beginning or end, but part of a continuing cycle of growing, harvesting, consuming, and composting…all while boosting local economies and protecting local waters along the way.


About the Author: Christina Catanese has worked at EPA since 2010, in the Water Protection Division’s Office of Program Support. Originally from Pittsburgh, Christina has lived in Philadelphia since attending the University of Pennsylvania, where she studied Environmental Studies, Political Science, and Hydrogeology. When not in the office, Christina enjoys performing, choreographing and teaching modern dance.

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