Stalking the Mushroom Caves

Luciano Martin and his brother, Juanito, both look as though they are hewn from the same rock that forms the arches and pillars of their medieval mushroom caves near Rouen. Sturdy and handsome, they look like they were chosen by Central Casting to spend the better part of their time with small, bright lights on their foreheads, tending to a variety of succulent fungi deep in the hills of Canteleu, a Rouen suburb.

Juanito, the elder of the two brothers, whose Spanish father fled the Franco regime in Spain to settle in France, has been cultivating mushrooms for 25 years. He originally bought the land that holds the giant caves, which go as deep as 150 feet and cover almost an acre and a half, to stock merchandise for his building business. The mystery and allure of their original function, which was mushroom cultivation, overtook him, and he went into the business himself. Luciano, who was in real estate, joined his brother in the mushroom business three years ago.

Rouen is a bourgeois city of winding streets, luxurious boutiques, a gorgeous cathedral and a very well-dressed population. One would never guess that a stone’s throw west of its bustle are these troglodytic caves whose damp, chill atmosphere is perfect for growing mushrooms.

In the Middle Ages, there was a pair of natural caves in the hillside. When work started on the great Gothic cathedral in the 12th century, the builders turned to the soft white rock in the nearby hills. As the cathedral grew, so did the caves.

Samples and drinks

At the turn of the 20th century, the caves were expanded. “Prisoners did the work,” Luciano says. “You can see the marks of their tools.” Ceilings were rounded and a simple aeration system installed so mushrooms could be farmed. During World War II, the German army conscripted the caves to store their equipment. Post-war, the caves were left fallow until Martin bought them. I visited the brothers on a gray winter day. It was chilly, but nothing like the preceding weeks, when temperatures hit record lows. As far underground as we work we felt the cold,” Luciano said. “The mushrooms had a hard time growing.”

They met me at the mouth of the caves, which doubles as a bar and a dining area in fine weather. “Sometimes we serve drinks and samples, to attract customers,” Luciano said. He handed me a lamp to wear on my forehead, and made sure his brother knew we were going into the caves. “We watch out for each other. No one ever goes into the caves without the other one knowing it; our cell phones don’t work underground, so we have to be careful. If whoever is in the caves doesn’t emerge after two hours, the other one goes in after him.”

We slowly made our way into the belly of the earth, our lights shining feebly in the close darkness. “Stop, listen,” Luciano said. There was nothing to hear and the farther we went, the more silent it became. Aside from the electrical wires that ran high along the walls, and a metal grate here and there, these caves might have been untouched for more than a century. “I spent a career in real estate,” Luciano said. “I love the silence in here!”

Paris or Anjou

We rounded a corner into a large cavern where low, flat metal tables set side by side were filled with what looked like friable, pale-brown earth. “We grow button mushrooms here,” Luciano, said. He explained that the metal tables are delivered every six weeks or so, already filled with what is called compostage, a blend of earth and button mushroom mycelia. “The mycelia look like white powder,” Luciano said, bending low over one of the tables so his headlight flashed on what looked like a rivulet of gray mist in the compostage. He then pointed at what looked like a miniature white pebble. “That’s a baby mushroom,” he said, as proudly as if he’d created it himself. “And all that gray mist you see will turn into mushrooms too.”

Button mushrooms that are all white are called champignons de Paris; those that are brown-topped and white stemmed are called blonds d’Anjou. They are members of the same family, Agaricus bisporus. Both are grown on low tables, and they take about six weeks to mature. The electricity that Juanito installed operates lights that stay on for six hours every day. “Mushrooms like light,” Luciano said. “It calls them out of their soil.”

We continued on our way in the dark, slowly turning corners, and dipping our heads as we went through arched doorways. Columns here and there looked just like mushrooms stems; the air was cold, still and damp. “We can control the temperature,” Luciano said, pointing to doors in the walls that opened onto tunnels that let in air from outside. “We open these doors when we need to; the air outside is always warmer than the air inside—except for this winter, when it was so cold we had to keep everything closed all the time.” The humidity remains constant.

Oysters and shiitakes

Our destination was a large, low-ceilinged chamber at the back of the caves that was lit up like Broadway. A series of shelves held what looked like rectangular white or black plastic boxes, standing on end in tidy, regular rows. I started over to see them up close, but Luciano called me back. “Look here,” he said, making sure his light was shining on the wall. “The prisoners carved their initials, and they made designs on the wall.” Sure enough, there was a symbol that looked something like a sundial, next to the Roman numeral XIV.

We both went to take a look at the boxes sitting on shelves. “These are ballots that we get from a supplier,” Luciano said. “They’re packed with a blend of soil, birch and beech wood shavings, and mycelia that gradually turn into mushrooms.” The sturdy plastic coverings are slit to allow the mushrooms to emerge, which they do in stages.

The pleurotes (family Pleurotus), or oyster mushrooms, emerge as dense groups of dark-gray balls, which look something like clusters of pencil erasers stuck together. Over a period of about two weeks these emerge and grow into graceful layers of silvery-gray leaves. “We harvest everything by hand,” Luciano said, gently breaking a bunch of the leaves off. He turned them over, to reveal delicate creamy white gills.

We moved on to shelves of shiitake mushrooms (Lentinula edodes), which burst forth from their white-covered plastic rectangles individually, rather than in clumps. Drier and sturdier than the pleurote, the rust-capped shiitake is considered by the French to be a substitute for the valued cèpe, or boletus mushroom. “The flavor is a bit smokier than a cèpe,” Luciano said. “And the texture is better—it’s not so slimy.”

Grown and gone

The shiitake is the most difficult of the mushrooms to cultivate, according to the Martins. “We don’t really know why,” Luciano says. “Sometimes, nothing will come out of a ballot. Once the mushrooms emerge, though, they’re ready to harvest in three to four weeks.”

A ballot, or rectangular mushroom block, contains enough mycelia to produce mushrooms over about a three-month period. Towards the end of its productivity, the box deflates and becomes heavy with water. “The mushrooms attract humidity— they need it to grow,” Luciano said. “When we harvest them, they leave water behind.”

When the button mushrooms are all harvested, the spent compostage on each table is replaced by a new batch, rich with mycelia. When the ballots finish producing pleurotes and shiitakes, they are disposed of and replaced by tight, new ones. “Mushrooms are basically heat and water,” Luciano said, waving his arms to include all the ballots with their fungal decor. “Our job is to control the air temperature and the light, and we’re in here all the time, supervising, checking and harvesting.”

The Martins grow mushrooms by hand, and they also market them that way. Each week, they carefully set their precious fungi in wooden crates and take them to farmers’ markets within a 50-mile radius of the caves. Once there and on display, those mushrooms don’t stay put for long.

A Little Mushroom Info

Mushrooms are a source of protein and very low in calories. Button mushrooms are delicious raw or cooked; other varieties are best cooked, quickly over moderate heat until tender.

Shiitake Long considered a health food in Asian cultures, the shiitake contains vitamin D, vitamin B and iron. They should be cooked just until softened and slightly caramelized.

Button Whether white and brown, they contain vitamin B, magnesium and selenium.

Oyster Contains vitamin B and folate, as well as protein.

To clean mushrooms, trim the stem tip, then wipe them using a damp dish towel. If they are very dirty and you’re in a hurry, put them in a colander and rinse very quickly—they absorb water ,so the faster the better. Keep mushrooms in a bowl lined with a paper towel and covered with plastic wrap or aluminum foil. They will keep for about a week in the refrigerator.

WARM MUSHROOM AND MACHE SALAD

Salade Chaude de Champignons et Mache

For the mushrooms:

1 tbsp extra-virgin olive oil

1 clove garlic, green germ removed, minced

1-1/2 lbs (750 g) mixed shiitake, pleurote and button mushrooms (or just buttons), wiped clean, stems trimmed, thinly sliced

Fine sea salt

Freshly ground black pepper

For the mâche:

1 tbsp freshly squeezed lemon juice

Large pinch fine sea salt

¼ cup extra-virgin olive oil or walnut oil

1 shallot, thinly sliced

1 tablespoon ground walnuts

8 cups mâche (or other tender lettuce)

To cook the mushrooms, put the oil in a large, heavy skillet over medium heat. Add the garlic, stir, and when it starts to sizzle, add the mushrooms. Season generously with salt and either stir or toss. Cook, stirring or tossing often, until mushrooms are tender and golden, about 8 minutes. Remove from heat and add pepper. While mushrooms are cooking, put lemon juice and salt in a large bowl, whisk, then whisk in the oil. Add shallot and walnuts, whisking until combined. Add the mâche to the dressing and toss. Add the hot mushrooms to the salad and toss until all ingredients are combined. Season to taste, then serve immediately.

Susan Herrmann Loomis teaches cooking classes in Normandy and Paris. www.onruetatin.com. Find her cookbooks in the France Today Bookstore.

Originally published in the April 2012 issue of France Today