How Truffles are Grown - and What Makes Them So Special?

Truffles are notoriously difficult to cultivate. But in France, thanks to centuries of practice, an amazing 95% of truffles come from agriculture. To get this right, farmers raise saplings from seed in a controlled environment, before introducing truffle spores into the root system, where they grow in a symbiotic relationship with species like oak, beech, hazel, or fir. Truffles also grow symbiotically with trees in the wild. But the spores are spread with the help of wild animals like pigs and bears. Read on to find out more about how truffles, "the black diamond of the kitchen", are grown.

What are truffles? 

Truffles are fruiting bodies (aka spore-producing organs) of the fungi family ‘Ascomycota’. Functionally, they are pretty much like mushrooms, except they grow under the soil. The main biological function of a truffle is to spread spores, which in turn gives rise to new offspring.  

How are truffles grown?

Since truffles grow under the soil, the way they spread spores is slightly different from how mushrooms do it. Truffles use their unique aroma to attract ‘fungivores’ who enjoy snacking on them.¹ In the Northern Hemisphere, these animals include small mammals like mice, squirrels and rabbits.² In the Southern Hemisphere, the main truffle enthusiasts are rat kangaroos, armadillos and meerkats.²

Larger mammals like pigs, deer, bears, baboons, and wallabies also seek out truffles.² When consumed, most of the flesh is digested, but the spores pass through the animal’s body unscathed. These spores get back into the soil via the animal’s faeces, which is usually deposited in a nearby area. This is especially important because the spores will need to find their way to the roots of their host trees, which are often local to specific ecosystems.

Unlike most plants that can convert sunlight into energy in a process called photosynthesis, truffles are instead totally dependent on certain trees to carry out this process for them. In return, the truffle helps its host tree by using its hyphae to reach nutrients and water from pockets of soil that the tree cannot reach by itself.¹ This kind of symbiotic relationship between fungi and the roots of a tree is called mycorrhiza.
 

Cultural and culinary significance of truffles

The first mention of truffles appears in the inscriptions of the neo-Sumerians from the 20th century BCE regarding their Mesopotamian enemy's eating habits.³ Other notable ancient records include the writings of Theophrastus, a Greek philosopher in the 4th century BCE, and the records from Roman naturalist Pliny the Elder in the 1st century CE.²

Today, truffles are grown in temperate areas of Mediterranean Europe, western North America and Australia.² They find their way into some of the world’s best restaurant kitchens within a few days (sometimes hours) of being foraged. Creamy pasta dishes, eggs, potatoes, and poultry are some traditionally popular companions for truffles. Thin slices or shavings are used to garnish the dish. Due to their perishability, seasonal availability, and high cost, not everyone can enjoy truffles. This makes truffle-infused condiments like salt, olive oil, and butter quite popular among gourmands. Oprah, for instance, is said to refuse to travel without ensuring that she, her assistant, and the security detail have packed surplus truffle salt!⁴
 

A family of pigs hunt for truffles in buried in the forest.

Foraged vs farmed truffles

Much like animals, humans are attracted to truffles because of the scent they produce. The aroma and taste of truffles is often described as musky, earthy, and pungent and can be attributed to the pheromone androstanol and other volatile compounds.

Truffles need to be recovered (foraged) from under the soil. Traditionally, this was done with help from pigs. Sows are attracted to the scent of truffles because truffles contain the pheromone androstanol which is a sex hormone also found in the saliva of male pigs. However, it is incredibly difficult to convince the sow not to eat the truffle after she works hard to locate it. Dogs on the other hand, are also great sniffers and will happily settle for an alternative treat. Therefore, truffle hunters today prefer to use trained dogs for their foraging trips.

Because of their high value, the possibility to cultivate truffles has always been a topic of much interest in different parts of the world. Today, only a handful of truffle farms exist. Farmers grow truffles by inoculating the roots of saplings with truffle spores, then harvesting the truffles in 6 to 7 years. This technique was first recorded in 1969.⁵ However, growing truffles requires a complex combination of appropriate weather conditions, soil chemistry, and a bit of luck to grow successfully. As a result, the yields from truffle cultivation remain uncertain and can prove a risky investment to farmers. But in France, farmers are particularly good at cultivating truffles: an estimated 95% of truffles in France come from farms.⁶ Farmers have to grow saplings in a clean environment before inoculating the roots with truffle spores and planting them out in the field. The best species for this are trees like oak, birch, hazel, and fir.⁷