Raising American Truffles

Rodale’s Organic Gardening, October 1987
by Larry Korn

You can grow these European delicacies in your own Backyard .

Nearly everyone has heard of truffles—the flavorful, underground fungi popular as a gourmet food in Europe for centuries. Few Americans have ever tasted these small potato-like fruits because they are simply unavailable, or at about $400 a pound they might as well be. Even in France, the highly sought Perigord truffle is rare and very expensive. But now truffle species have been found in several parts of the United States. In addition, truffle hunters and commercial growers are developing ways to raise the delicate fungi all across the country.

Truffles are the fruiting bodies of certain mycorrhizal fungi—fungi that live partly in the soil and partly in the roots of specific plants. They grow in many shapes, but most are small round objects resembling dirty golf balls. Because truffles sprout below the ground, it is not easy to find them growing in the wild. In France, pigs and dogs are trained to sniff out the pungent fruits lying beneath the forest floor.

Although researchers have known of the existence of native truffles in North America since the turn of the century, only in the past 10 years has amateur truffle-hunting caught on. The North American Truffling Society (NATS) of Corvallis, Ore., conducts forays to the mountains in search of these flavorful delicacies. Some of the rare specimens collected are listed in the NATS newsletter, including the scientific name and the conditions where the truffles were found.

Large concentrations of truffles have been found in the mountains of Washington, Oregon, California, and British Columbia. Native truffles have also been discovered in Texas, Colorado, Michigan, Tennessee and at higher elevations in New England. In fact, many people have truffles growing in their wooded backyards right now and don’t even know it.

Amateur collectors have also begun scouring the mountains for commercial harvests of chanterelles and other wild mushrooms. The rapid increase of foraging for wild mushrooms, however, has alarmed environmentalists, who worry about depleting the forest of these important fungi and also about the damage uncontrolled harvesting may cause.

Gary Menser, a former mushroom broker now working at Oregon State University, is trying to help solve this growing problem in an innovative way—by developing home production of truffles here in the United States. Menser believes truffles can be successfully produced in many parts of the country.

Menser’s truffle knowledge was developed in France, where he learned the newly developed methods for inoculating tree and shrub seedlings with truffles. He has since installed several large plantings in the Pacific Northwest, including a 10,000-tree orchard near Aberdeen, Wash. The trees are Douglas fir inoculated with a native Northwestern truffle, Tuber gibbosum.

He also planted 1,000 trees—which he lugged from Europe—in the hill country of Texas near Austin and San Antonio, since the area’s soil and climate are similar to that of southeastern France. Another group, Agri-truffle, working in the same region of Texas, has planted some 40 acres of trees inoculated with the black Perigord truffle, Tuber melanosporum. They used wild hazelnut, California oak and native Texas oak trees. The truffles take six to twelve years to begin fruiting. Since the oldest planting is only four years old, yield data is not yet available. But the method has worked reliably in Italy and France. According to early reports, the trees planted in this country are thriving. These initial plantings will help determine the best soil conditions and techniques for growing truffles in America.

Due to these new developments, many American gardeners can plant their own truffle orchards. Once established, the truffle orchard requires little water or maintenance, no fertilizer and only a light annual tilling. The French truffle grower prefers a poor, shallow, gravelly soil that is slightly alkaline.

In that kind of soil, the truffle’s root system develops horizontally, close to the surface, and the necessary root-fungus relationship is firmly established. If you plant inoculated hazels, in several years you could be harvesting a forage crop of nuts from above the ground and truffles from below.

To get started, clear an area of competing brush and trees, and add lime if the soil is acid. Menser has found that it is best to plant at least 20 trees in grid rows 10 to 12 feet apart. “Plant perennial rye as a ground cover or intercrop with vegetables and flowers while the trees are maturing,” he suggests. “For example, the French grow rows of lavender in young orchards. After a few years the truffles will send out a compound that inhibits the growth of other plants. A brulee, or burned-looking area, develops near the base of the trees. Then the truffles sprout every fall and winter. How many are produced depends a lot on the weather. Drought and extreme cold inhibit fruiting, but the truffles are insulated from the weather, to some extent, by the soil that covers them.”

No one is sure how long it will be before truffles are as common in the United States as the white Agaricus mushroom, but better methods for growing truffles and inoculated seedling stock are already available. The lucky Americans who establish truffle orchards will be able to enjoy the finest French cuisine right from their own backyards.