Fungus Farming: Monterey Mushrooms Grow in Tennessee

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Monterey Mushrooms’ white buttons

It’s a bustling farm, but one that defies traditional farm rhythms of sunshine, rainfall and wide-open spaces.

Shrouded in darkness, this farm lies primarily under roof, within the confines of a stark concrete warehouse that sprawls across seven acres. The “fields” are thousands of trays stacked in neat rows on concrete slab. There are no seasonal chores, since a new crop is planted every other day and harvested year-round. And, here, fungus is actually a good thing.

From Farm to Grocery Store
Despite its cave-like environment, the Monterey Mushrooms farm is a model of agricultural productivity, trucking out more than 600,000 pounds of mushrooms every week to grocers and food suppliers throughout the Southeast.

Located in Loudon, about 28 miles southwest of Knoxville, it is one of 11 farms operated by Monterey Mushrooms, a Watsonville, Calif.-based grower with farms in the United States, Canada and Mexico. The Loudon plant was built in 1977 by Ralston Purina and eventually became part of Monterey Mushrooms. With 550 workers, it is easily the biggest mushroom farm in Tennessee, growing primarily white buttons along with some portabellas.

“Although we are producing an agricultural product, I see our operation more as a manufacturing facility, or more specifically, a food plant,” says general manager Greg Sweet. “The majority of our operation is performed indoors, allowing us to control most of the growing variables. We focus more on growing what we can sell, when we can sell it – versus selling what we grow.”

National mushroom sales are stable and solid. U.S. growers sold 853 million pounds at an average of $1.06 per pound from their 2004-2005 crop, according to the National Agricultural Statistics Service. The vast majority of farms are in Pennsylvania and California. However, farms like the one in East Tennessee are scattered across the rest of the country in strategic marketing areas.

Meet a Mushroom Farmer
Bob Moore is a veteran mushroom farmer, working in Colorado and Pennsylvania before moving to East Tennessee in 1981. As quality assurance manager for the Loudon farm, he helps oversee the operation.

“This isn’t a cave, but it might as well be,” Moore says of his workplace. “There are no windows, and, when you’re here, you don’t know what time of day it is. You just focus on your job. Every day is the same, but every day is different, too.”

It’s the chemistry behind the finicky mushroom that makes each day unique. The mushroom is a fungus. Because it does not have chlorophyll, it is not a green plant and cannot use energy from the sun. Instead, it extracts its carbohydrates and proteins from a nutrient-rich food base. Thus, the first phase of the farm operation is making compost.

“Good compost is the key ingredient in producing a successful mushroom crop,” Sweet says. “Some growers say compost contributes as much as 80 percent to the overall production process.”

Five acres outside the warehouse building are dedicated to the composting process, bringing in tractor-trailer loads of stable bedding from Kentucky Thoroughbred farms and mixing it with wheat straw from Tennessee, chicken litter and nitrogen-rich urea. During the 22-day process, temperatures within the piles reach up to 180 degrees and spark chemical changes that transform the compost into a food source for the mushroom.

The compost “food source” is mixed with vegetable oil and water and poured into wooden trays that are 6 feet long, 4 feet wide and 8 inches deep. After a pasteurization process kills any pests present in the compost, these trays become the “gardens” where mushroom seeds, or spawn, are planted. (Mushroom seeds are actually rye seed inoculated with the mold of a strain of mushrooms.)

How To Grow Mushrooms
To grow mushrooms, farmers try to create the same conditions that occasionally cause mushrooms to spring forth in your front yard in the spring and fall.

Covered with a layer of peat moss, limestone and water, the trays are shuttled from room to room – each with carefully controlled temperatures and humidity levels – as they support the crop for 31 days from planting to picking. As the ammonia level drops and the compost’s odor turns from musty to sweet, the spawn fuzzes and turns into “pins,” which eventually form “buttons.”

“A mushroom is ready when the stem starts to elongate and get thinner and the cap starts to flatten out,” says Moore. “They’re picked before the veil opens between the cap and the stem. Our pickers are trained to recognize this. We’re after about seven pounds of mushrooms per square foot of tray, and we have 1,100 trays per crop.”

“It’s very tough work,” says David Beyer, associate professor of plant pathology at Pennsylvania State University, who has visited the Loudon farm. “Growing mushrooms is 24/7 and takes a lot of attention to details. I’m impressed by the team effort in Loudon. It’s not unique to the industry, but it’s certainly a class act.”

Make the Most of Your Mushrooms
When it comes to using mushrooms at home, here are a few tips to consider:

• Selecting: Look for a fresh, smooth appearance with a dry (but not dried) surface. A closed veil (the thin membrane under the cap) indicates a delicate flavor; an open veil means a richer taste.

• Storing: Always keep mushrooms refrigerated. If purchased in a wrapped package, don’t open until ready to use; store any unused mushrooms in a paper bag. Don’t rinse until ready to use. Mushrooms are best used soon after purchase, but will usually keep up to a week.

• Cleaning: Before use, wipe mushrooms with a damp cloth or soft brush to clean off any remaining peat moss. Or rinse under cold water and dry gently with paper towels.

Source: The Mushroom Information Center


  1. Harry E. Wallace

    March 24, 2011 at 10:25 pm

    My wife and I operate a small native plant nursery in northwest Alabama. We also operate a landscape installation company. We are interested in mushroom compost in bulk. Can you provide information to us?

  2. Grace McMann

    September 12, 2011 at 3:47 pm

    My brother lives in PA and he buys soil from the mushroom farm. Do you, or do you know any one in TN that sells soil.
    Grace in Sparta TN

    • Blair Thomas

      September 20, 2011 at 2:42 pm


      To find information about the soil you are looking for, I recommend contacting your county extension agent. In White County, that contact information can be found on the University of Tennessee’s Extension website here. You can also browse the UT Extension website for help with your gardening questions.

      Hope this helps!


      Blair Thomas
      Content Coordinator
      Tennessee Home & Farm

  3. peggy dixon

    April 26, 2012 at 2:47 pm

    i was told that you sell mushrooms in bulk , and i was wondering how much? i am a diabetic and love them and they are great for diabetics. my husband and his boss who used to run a fruit stand came there to get them.

    • Blair Thomas

      April 27, 2012 at 9:14 am


      For information about purchasing mushrooms, contact Monterey Mushrooms directly at (800) 333-6874.

      Thanks for reading!

      Blair Thomas
      Tennessee Home & Farm

  4. Chambers-King

    April 14, 2013 at 1:23 pm

    current price on your product/and or your by-product(mulch)

    • Jessy Yancey

      April 15, 2013 at 8:45 am


      For information on Monterey Mushrooms, please contact them directly at Hope this helps!

      Jessy Yancey
      Tennessee Home & Farm magazine

  5. Mary Huffstetler

    April 15, 2013 at 7:30 pm

    Iwould like to know if you ever deliver the compost. we would love to have some.
    we live in Alcoa and would be glad to pay. thank you
    Mary Huffstetler

    • Rachel Bertone

      April 16, 2013 at 8:31 am

      Hi Mary,
      We recommend contacting Monterey Mushrooms directly at (800) 333-6874 or

      Rachel Bertone

  6. Az

    August 19, 2013 at 10:54 am

    A good reference point for supplies of mushrooms is, do have a look !!!

  7. brian vaudrin

    April 28, 2014 at 10:43 pm

    A blessing that you do what is needed to feed our communities.

  8. Gary Parson

    July 23, 2016 at 10:51 am

    Do you provide tours? We would enjoy seeing your facility and want to bring our two granddaughters.

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