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Chester County Press

Inside the state-of-the-art D’Amico mushroom farm

09/22/2023 12:31PM ● By Ken Mammarella
Inside the state-of-the-art D’Amico mushroom farm [7 Images] Click Any Image To Expand

The D’Amico family near Avondale is world-famous for its multiphase techniques to create mushroom compost, the fickle medium for growing mushrooms.

And the family’s quarry is famous in a different way: It sometimes gets so many requests to collect stones from building demolitions and excavations that it pauses its quarrying. 

“Making compost is a challenge and an art,” said John A. D’Amico, who with his wife, Sharon, own  interlocking businesses that sprawl over 115 acres. 

They include D’Amico & Sons Farming, which is developing those state-of-the-art techniques to create compost; J.D. Mushrooms, handling mushroom growing, picking and wholesaling; and, D’Amico Quarry. Their son John J. runs the mushroom operations, and their son Mario runs the quarry. Cousins run To-Jo Mushrooms, which sells mushrooms produced by the other branch of the family.

“We are one of the best in America” in a second phase of composting, Mario said. The family is helping to lead the world in developing a way to automate and speed up a third phase of production: compost that’s inoculated with mushroom spores.

Although they don’t market to consumers, the D’Amicos are ready with tips for them. John J., for instance, touted “the Blend,” a Mushroom Council concept of adding chopped mushrooms to ground meat, to increase umami, reduce costs and help the environment.

“People don’t realize what a fresh mushroom tastes like,” said John A. “It tastes like a radish.”

An emphasis on recycling

Composting means creating the mix that mushrooms grow in. The most important ingredients are straw, hay and horse manure, John A. said, noting it’s critical to get the right carbon-nitrogen ratio.

The family recipe also includes fodder (corn stalks and leaves left over after harvest, and also known as stover), powdered chicken manure, cocoa hulls (another leftover, after beans are sent their way to create chocolate), corncobs (one more leftover) and gypsum (a mineral that causes other materials to make clumps, a process called flocculation, which allows for air to flow more freely through it all). 

“Mushroom farmers are the biggest recycling industry in the world,” said John J.

Recycling also extends to water. A million-gallon tank – the largest in the area – holds well-water and water recycled from the growing rooms and To-Jo’s processing plant. “We basically recycle everything,” John A. said. Spent mushroom soil, which cannot be reused in mushroom farms, is sold to other companies that process and package it for use on lawns and gardens.

Hundreds of photos and a few videos show off various steps on the D’Amico & Sons Farming page on Facebook.

The first phase of composting starts by submerging bales – hay, straw or fodder – in water for two minutes and then letting them rest for 10 days. The bales are then broken open, blended with the other ingredients and then spread in long rows on concrete pads. The rows – starting 8 feed high and wide – are called ricks, and the pads are called wharfs. 

For 18 to 20 days, the ricks are monitored, moistened and turned so fermentation occurs properly. Automatic turners regularly run down the rows, picking up the material, running it through what is essentially a giant blender and depositing the aerated mix. The process naturally hits 160 to 180 degrees. Improperly handled ricks, unfortunately, can develop a strong-smelling anaerobic core.

“If you ask any mushroom grower anywhere around here ‘Do you smell that?’ They’ll say ‘Yes, It does smell like money,” John J. said, using the classic light-hearted line about that aroma.

New frontier for inoculation

The second phase involves pasteurization in tunnels, with more moistening and monitoring over six days. The air is first kept at 114-118 degrees for conditioning, then hotter, with the compost at 140 degrees for 10 hours for pasteurization, then cooler for more conditioning. “This is the best technology you can get for the way we do it,” Mario said. 

The family’s tunnels use an unusual spigot floor, John J. said, with spigots pushing air into compost. “Our trucks are a lot different, too. They go directly down onto a conveyor belt. We’re cleaner.”

The third phase, now being tested, involves inoculating the compost with mushroom spores. The spawn run traditionally occurs in mushroom houses. “The only other person doing phase 3 on a spigot floor is in Italy,” John J. said.

By handling the third phase in bunkers, they shorten the time each room in the mushroom houses are used to grow a crop, from eight weeks to six. Staffing and utility costs would drop, and gross revenue would increase.

All that’s a big deal in Chester County, which, coupled with nearby facilities in Berks and Cecil counties, grows more than 60% of all mushrooms produced in the U.S.

“Labor inflation is driving us to more efficient equipment,” John A. said. “The family farm is struggling, but we’re looking to be a survivor.”

Stonemason began the family business

The D’Amico family legacy in the Avondale area began in 1932, when stonemason Joseph A. D’Amico bought land that just south of New Garden Airport. He created a quarry and mushroom farm.

Some quarry products are marketed as Avondale brownstone and D’Amico mica. Brownstone is, yes, mostly brown, but it can also feature blues and grays. The quarry also sells stone quarried elsewhere, such as pieces from India as nicely matching windowsills for the brownstone. 

The family is proceeding slowly on the quarry, said Mario D’Amico, with staff sometimes devoted to handling stone from demolished buildings and excavations. 

Quarrying starts with a hydraulic hammer breaking into the hill, and then the hammer is used again to break the stone into more manageable pieces. The pieces are then split along by a machine called a guillotine and cut with a diamond-tipped saw into usable pieces, often as a 1¼-inch-thick veneer.

Details are at

Stone from the quarry is used on structures all over the property, and it also covers facades of the new Kennett Library and the Hockessin Athletic Club. And it’s the star of a grotto in the main fountain garden of Longwood Gardens. Longwood calls it a “rough-hewn cave that feels centuries older than its surroundings” and says it’s “hidden in plain sight.”

“I love rocks,” said quarry manager Saul Torres, an employee for 28 years. “Outside my house, inside my house, but my wife stopped me from adding it besides our bed.”