How Are Mushrooms Grown?

//How Are Mushrooms Grown?

How Are Mushrooms Grown?

Did you try Wendy’s Portabella sandwich last fall? How about a slice of mushroom pizza? Any fungi on your salad recently?

If you answered ‘yes’ to any of these questions, and you live anywhere close to the East Coast, then chances are your mushrooms were grown at Phillips Mushroom Farms in Kennet Square, Pennsylvania. The vast, nondescript warehouse-style buildings of Phillips Organic Mushrooms produce shipments approaching 1 million pounds of mushrooms a week. Now that, ladies and gentlemen, is a big load of shiitakes!

I recently had a behind-the-scenes tour of this farm, seeing for myself how mega-scale organic mushrooms are grown. Join me as I walk down a path of manure and fungus, exploring the fascinating, funky world of mushrooms.

Your author, complete with hair and beard net. Mushrooms are susceptible to all sorts of competing fungi and viruses, so this free-range farmer had to wear a biosuit.


Fresh mushrooms being picked. These mushrooms double in size every 24 hours, making harvesting a daily, year-round chore.


A Portabella cap, with healthy pink gills (difficult to see in this light) that indicate freshness. Younger Portabellas are harvested alongside the slightly older fruits, and dubbed ‘Baby Bellas’. Wook at dose wittle mushrooms in the background… d’awwwww!


How do mushrooms grow? In nutrient-rich compost, mostly. The white strands are the mycelium, the living fungus. The mushroom itself is simply a ‘fruit’ of the mycelium that releases spores. The mycelium grows in a black compost of straw and horse manure.


A shitake mushroom, growing out of a homemade ‘log’. These logs, which resemble loaves of artisinal bread, are primarily made of red oak sawdust.


Row upon row, stack after stack, vast rooms containing thousands of shitake logs wait in the semi-darkness. Each log is hand placed and hand picked, and yields several pounds of mushrooms across the course of a few weeks.


Mushrooms love moisture, and here the ‘logs’ are stacked into crates, waiting to be dunked into large soaking pools.


Ferial Welsh, the Mushroom Lady. If you’ve shopped at Baltimore or Washington, D.C. farmers’ markets, you can’t help but have seen Ferial; she has been selling mushrooms for Phillips and Mother Earth Organics for over 15 years. Find her stand at Arlington Courthouse, Dupont Circle and Falls Church. Her smile says it all…she loves mushrooms!


Shitakes waiting to go on a refrigerated truck. Much like shell fish, mushrooms remain alive and breathing long after they are harvested. I was told that, in most cases, mushrooms remain alive until they are cooked.


Each type of mushroom grows in a different environment. Here, black plastic is stuffed with compost and shaped into vertical logs to allow yellow oyster mushrooms to flourish.


A glimpse inside the bag. Straw and cocoa shells (gleaned from Hershey’s Cocoa, just up the road in nearby Hershey Pa.) are inoculated with mushroom spores, providing the white mycelium with nutrients.


Grey oysters…


…and yellow oysters.


‘Oyster poles’, where the vertical logs are placed.


The Maitake. Each plastic-encased maitake log can only grow one or two mushrooms per cycle. Generations of trial and error have gone into getting these finicky mushrooms to perform with consistency.


Phillips provides over 200 different private labels, including to Whole Foods and Wegmans. If you’ve purchased mushrooms from any grocery store on the Eastern seaboard, they probably originated here.


This mushroom farm employs over 400 people, and supports another 50 through ancillary jobs such as compost production. Here, dozens of people pack and label mushrooms.


Of course, every production facility must have a conveyor belt! In this picture, freshly sliced mushrooms wend their way towards containers and shrink wrap.


Kennett Square, Pennsylvania is officially mushroom crazy. On Main Street, a fungus-themed gift store sits opposite a restaurant dubbed Portabella’s.


The Mushroom Lady’s display at farmers’ market. Ferial travels to Pennsylvania several times a week for fresh-picked mushrooms, ensuring that they are even fresher than the ones available at high-end supermarkets.


Ready to doff my beard-net! Hope you enjoyed the tour :^)

Check out my books, all about food, farming & living the good life!

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By | 2018-08-04T09:17:27-04:00 March 20th, 2013|Farm|18 Comments

About the Author:

Forrest Pritchard is a full-time sustainable farmer and New York Times bestselling author, holding a BA in English and a BS in Geology from William & Mary. Smith Meadows, his farm, was one of the first “grass finished” operations in the country, and has sold at leading farmers’ markets in the Washington DC area for two decades. Pritchard's books have received starred reviews from The Washington Post, Publishers Weekly, Library Journal, NPR, and more.


  1. Katje Scott March 20, 2013 at 7:48 pm - Reply

    I grow Oyster Mushrooms in New Mexico and i was wondering why you use black plastic. I use clear and wanted to know if it made a difference.

    • Forrest Pritchard March 20, 2013 at 8:15 pm


      Not really certain, I didn’t ask them. But will be happy to follow up later this weekend when I see Ferial, the mushroom lady. In hindsight, I did notice that they grew certain varieties in clear plastic, and others in black. One thing I can say is that they have a reason for EVERYthing they do… they even have a mushroom consultant come in from Denmark several times a year to double check their techniques.

  2. Jennifer Lee March 21, 2013 at 7:10 am - Reply

    As someone who eats at least a carton of shiitakes a week, I really appreciated the tour and seeing where my shrooms come from! Thanks, Forrest and Phillips Farm!

    • Forrest Pritchard March 21, 2013 at 2:30 pm

      Thanks, Jennifer. As someone who has basically lived outdoors for the last decade and a half, I had my doubts about food that’s grown completely indoors. But everything here felt appropriately damp, musty and composty-smelling, yet very clean and organized.

      If I were a mushroom, I’d probably like growing up here :^)

  3. Trista March 22, 2013 at 6:23 am - Reply

    That was such a cool virtual tour! Thanks for enduring a beard guard for us, and for taking lots of pictures. I remember the incredible quality of the Dupont Market mushroom lady and always wanted to see her operation. MMMMmmmmmm, maitake! Shiitake! Mouth watering now.

    • Forrest Pritchard March 23, 2013 at 7:19 pm


      If I had to do it all over again, I’d shave my beard off and request a mustache guard.

  4. Libby@Everything's Coming Up Green March 22, 2013 at 8:42 pm - Reply

    This was so cool! Thanks for sharing!

    • Forrest Pritchard March 23, 2013 at 7:20 pm

      You got it, Libby! Up soon, a behind-the-scenes look at a small scale butcher shop…

  5. Suzy March 22, 2013 at 9:22 pm - Reply

    I am curious – TV chefs keep telling us to not wash mushrooms like we wash vegetables because they soak up the water. They all suggest simply wipe them with a damp towel to remove the dirt. So isn’t that not sanitary if they are grown in manure? I am thinking of all the diseases that transfers through the fecal-oral route…

    • Forrest Pritchard March 23, 2013 at 7:18 pm

      Hi Suzy,

      I think the best answer for this is that the compost is heated for several weeks in advance of bed preparation for the mushrooms, and during this period it reaches very high temperatures (in excess of 145 degrees). To a large extent, this kills off many of the undesirable pathogens that would be found in the manure. Still, common sense tells me that these mushrooms are picked by hand, and hands carry germs… so I feel like rinsing them off (as well as cooking them to proper temperature) is never a bad idea.

      But then again I’m a livestock farmer, so what do I know?

  6. Cookie Kinder March 23, 2013 at 7:16 pm - Reply

    What an intertesting tour. Thank you. Am sending this to my son. Know he will like it too.

  7. Carol Bentley March 23, 2013 at 7:33 pm - Reply

    I really enjoyed this, Forrest. Thank you.

    • Forrest Pritchard March 26, 2013 at 7:45 am

      My pleasure Carol, thanks! Getting to see other farms is an unexpected perquisite of being a farmer myself…

  8. VP1979 March 25, 2013 at 3:45 pm - Reply

    Loved the tour. Simply awesome!

  9. Shirley helman March 14, 2016 at 4:28 pm - Reply

    I will always wash mushrooms. I never soak them just rinse good. I will never eat mushrooms in a restaurant. Don’t care how they bake the dirt.

  10. lala July 7, 2016 at 12:27 pm - Reply

    “A million pounds a day” seemed awful high to me. Their website says 35 million pounds a YEAR. Also, dammit, it’s spelled “shiitake.”

    • Forrest Pritchard July 11, 2016 at 6:42 am

      Thanks for the notes, you’re absolutely correct… I meant ‘week’ not ‘day’. And shiitakes is now corrected as well, thanks again!

  11. Eliza January 11, 2018 at 7:34 pm - Reply

    Hey great article! You sound like a fun-gi…..GET IT!?? Hahhh!!

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