Recent advances in truffle research signal positive results for new growers, as methodology on how to grow truffles has improved substantially in recent years. Science continues to uncover new findings into the life-cycle of truffles.
This article provides valuable insight into the steps involved in how to grow truffles, however it is not intended as a concise guide to follow in setting up a farm.
Learning how to grow truffles
Cultivating truffles is reasonably complex, and successful production requires a complete understanding of truffle biology, farm establishment, maintenance and management.
Learning how to grow truffles through a comprehensive truffle growing course, should be the first and most important investment for a new industry entrant.
What are truffles?
A truffle is the underground fruiting body formed by a group of specialised fungi. Truffle fungi establish a relationship with a host tree, known as a mycorrhizal symbiosis. They live externally on and around fine tree roots and develop a vast network of mycelium in the soil, formed by microscopic filaments called hyphae.
Active mycelium searches for and returns nutrients and enhanced water intake to the tree. In return the tree provides the fungus with sugars and starches from the process of photosynthesis. The fruit body (truffle) is formed when two compatible strains of mycelium fuse under the right conditions, and depending on the species, this may occur in spring, summer and autumn.
All truffles emit some level of aroma from the ripening fruit body to attract animals, which locate, uncover, eat and redistribute the spore as they move about the landscape. For most of the truffle’s subterranean life-cycle however, there is no aroma and it remains undetectable until ripening begins, when the spores inside begin to mature. The aromas slowly form, developing in intensity until fully ripe, signalling its readiness to be found.
Despite over 200 species of truffle fungi existing in almost all continents, very few have pleasant aromas. A handful of species have significance in the culinary world and of these, two varieties are above all others in aromatics, value and interest: the Italian White and French Black truffles.
Where do truffles grow?
There are variable requirements among species. In this article, we will focus on the French Black truffle, globally the most widely studied and farmed species. This truffle is endemic to specific parts of Europe generally growing between elevations of 100-1000m (300-3600 feet). Typical climate zones are Mediterranean, Oceanic and Continental. Natural habitats are deep, well-draining, stony, calcareous, high pH (7.5-8.3) soils, on warm, exposed sites.
When growing this species in other parts of the world, farmers generally modify growing conditions, applying what has been learned from scientific studies of natural truffle grounds and the ecology of the truffle.
How to grow truffles – The site
Site selection is extremely important, involving a complex range of considerations including:
- Climate and location
- Soil characteristics: structure, texture, chemistry and pH
- Aspect, topography and existing vegetation
Truffle soils need to be extremely soft, loose and friable with a broad range of particle sizes. Loamy soils with reasonable even percentages of sand, silt and clay are best. Soils with clay contents higher than 30% are generally not suitable. The pH of the soil should be in the range of 7.5 – 8.
Truffle soil analysis
This is an essential part of site selection and should be carried out early in the process, as part of ‘proving’ eligibility of the site. Samples taken are sent to a laboratory for specific testing. An agronomist specialising in truffle culture, provides soil adjustment recommendations.
Truffle growing climate
There are specific parameters for the ideal climate range. In general, warm summers and cold winters with preferably, some incidence of frost is preferable. Natural rainfall should be in the range of 700mm/28 inches plus annually. Rainfall distribution should be reasonably even throughout the year, avoiding very wet winter environments.
Truffle farm design
Detailed farm design includes:
- Size of the plantation
- Specific planting pattern
- Contours for deep ripping
- Host tree species/number of trees
- Irrigation system layout.
How To grow truffles – Soil preparation
This may be extensive depending on soil type, compaction issues and recommendations made for pH and structural adjustments. General treatments include deep ripping to open up compacted soils, spreading and combining of recommended soil additives. Improved soils are generally left a minimum 6 months for adjustment, prior to planting trees.
A good water supply is essential for irrigations during warmer months. Water must be good quality with relatively low salinity readings. Storage may be a dam or large tanks. Supply may be water harvested from infrastructure roofing, a bore or licensed access to a creek or river.
Truffle farm fencing
Fencing may be required to keep out unwanted animals. Animals grazing the farm area will damage trees and re-compact soils, therefore fencing must be adequately designed to cope with the prevailing animal issues in the area.
Trees for growing truffles
Host tree selection decisions will be based on your learning, advice received, and the local environment.
The three main host trees used today for inoculation with French Black truffle are:
- French Oak, Holly Oak: Quercus ilex
- European hazelnut: Corylus avellana:
- English Oak: Quercus robur
Inoculated truffle trees
It is critical to source the highest quality inoculated host trees produced by specialist nurseries. Historically many farms received poorly inoculated tree stock, hence had little success in producing truffles. It doesn’t matter how well you prepare the soil and farm in general, if you don’t start with the highest quality trees, you will likely not succeed.
Industry tree certification programs, based on independent analysis of inoculated trees are available in many countries.
Planting inoculated truffle trees
Preferably carried out in autumn in most environments, however may also be spring, particularly in areas with harsh winters. Insulated tree guards are used for first 2 years, protecting young trees from small grazing animals, wind, herbicides and excessive heat.
Truffle farm maintenance
Ongoing maintenance required, includes annual pruning, pest, disease and weed control as required, summer irrigation, general repairs and mowing grass inter-rows.
Harvest – truffle dogs & pigs
Pigs were historically used for truffle hunting, now days dogs are used.
Harvest period is winter (for this truffle), with truffles gradually ripening throughout the season. Production begins slowly, generally in year 4-5, gradually increasing each year, potentially reaching commercial quantities by year 12-14. Farmers harvest on a weekly or bi-weekly basis depending on maturity/productivity/size of the farm. Farmers systematically search row by row, with dogs trained to locate truffles by scent. Well trained dogs generally only mark ripe truffle.
Learn more: Truffle pigs and dogs.
Freshly harvested truffles are placed in refrigeration until processed, ideally within 24 hours. Truffles are washed, dried then inspected for imperfections such as insect damage and bacterial rot. Grading criteria involves aromatics, shape, size and extent of any damage if any.
Handling and packaging
When fully ripe, truffles have a short shelf life of 2-3 weeks, with ideal consumption window of 8-10 days. Some aroma and weight is lost each day once a truffle is removed from the soil. As aromatics diminish, so may the experience for the consumer, hence ideally, freshly harvested truffles need to be cleaned, graded, packed (in a cold chain system) and posted/delivered to their destination within 48 hours.
The farmer has time to explore and build a market for the product. Gradual growth in annual yield allows growers time to build local clients such as restaurants, cafes, farmers markets etc. in early years. Supply agreements with food distributors and exporters are formed as yield develops. Exciting opportunities exist for organically grown truffles as this yet to be developed niche market will attract premium prices.
How to grow truffles – Financial considerations
When researching how to grow truffles, the first investment a new industry entrant should make is in acquiring essential knowledge for truffle farming.
TruffleGrowing.com’s online education includes project cost analysis, return on investment projections and creating a financial plan. Each project will invariably be different regarding establishment and management costs.
French black truffle (Tuber melanosporum)
The most commonly grown and studied truffle.
Retail prices range between $1,000-$1,500 per pound or $2,000-$3,000 per kilo in an average season makes this truffle the main focus for farmers and hence the subject of intensive study and research in recent years.
The species is widely planted in farming situations in Europe, Australia, USA, New Zealand, Chile, South Africa and other locations around the globe. When fully ripe, the French Black truffle has an intense, pungent aroma and earthy flavour. Its exterior (peridium) is dark and rough and the interior (gleba) is dark in colour with creamy white veins.
Other truffles of interest
Bianchetto (Tuber borchii). Excellent white truffle with similar qualities to its famed relation the Italian White, however with a more garlic aromatic. Harvested from mid winter to early spring.
Black Summer truffle (Tuber aestivum). Fruits from late summer into autumn often overlapping with the French Black winter truffle. This truffle’s aroma is milder than the French Black.
Oregon Winter White truffle (Tuber oregonense). Found from northern California to British Columbia associated with Douglas fir and at its best has a sweet musky cedar like aroma.
Oregon Black truffle (Leucangium carthusianum). Harvested from late autumn until spring. Appealing fruity musk quality to its aroma.