FUNDAMENTALS

How do you grow truffles? What are the elements and criteria you must consider? Unlike growing more conventional crops such as corn or soybeans, the science and know-how of truffle cultivation is by and large not available in the public domain. Here is a checklist based on our experience, scientific know-how and the truffle business landscape:

  1. Climate. This is the single most important factor, because it is not something you can amend or change once you establish your truffle orchard. The most relevant criteria for climate are the average summer and winter temperatures, and you can find more details below. By average, we mean temperatures averaged between day and night. Your location might have summer daytime temperatures in the 90s or even exceeding 100, but if they are offset by low enough nighttime temperatures such that the average is within the suitable range, then the climate can be suitable. To help you identify locations with climates ideal for the Périgord black truffle (Tuber melanosporum), we’ve created an interactive map showing locations with suitable climates.
  2. Climate Change. It’s not enough to consider just current climate based on historical climate data. Because a truffle orchard can continue to produce truffles for many decades, you’ll want to ensure that your truffle orchard will continue to remain in favorable climate and thrive well into the future even with climate change. It would be catastrophic if you invested extensively in a truffle orchard only to find out climate change will render it non-productive. We have developed a more detailed version of this interactive map that takes climate change into account. Please contact us and we will be happy to share it with you.
  3. Soil Conditions. There are two types of soil characteristics relevant for truffles. The first one is the physical property, which is a measure of the soil structure and cannot be easily amended. The other is the chemical property, which includes pH and concentrations of other elements, which are routinely amended. We will assess your soil for you to determine suitability, and to guide you through how to amend it to achieve optimal growing conditions for truffles.
  4. Water Availability. Even though you will have natural rainfall, it is essential that you have access to irrigation water. This is because the correct amount of moisture at the right time and frequency is critical for truffle production, and one needs to supplement natural rainfall with irrigation to ensure optimal harvest.
  5. Amendment with Agricultural Lime. There are myriad types of lime available, each having different chemical properties (some are detrimental to truffles) and fineness. The correct type and fineness need to be used, in order to bring the soil chemistry to the optimal point for truffles within a reasonable period of time.
  6. Irrigation System. Installing the correct irrigation system ensures not only tree survival, but will also result in vibrant growth of the truffle fungus and truffle fruiting.
  7. Orchard Management. This is where many growers face significant challenges. There is no one size fits all. One must tailor management methodologies to specific climate and soil conditions. Without the know-how of optimal ongoing orchard management, the vast majority of growers fail to produce much truffles, if at all.
  8. Monitoring. You’ll need to monitor your soil condition and truffle fungal colony health on a regular basis, especially when everything happens underground and you cannot easily see what’s going on, unlike being able to see apples growing on an apple tree.
  9. Dogs. You need to have a viable strategy to have a trained dog to harvest your truffles.
  10. Distribution. Many growers don’t think much about or plan for this critical element, when it’s the most important factor in converting your truffles to revenue. How you distribute will affect whether your truffle endeavor is a profitable one worth doing in the first place.

ATC has the experience, know-how and business network to help you with each of the above. For further detail, please feel free to contact us.

Microscopic view of truffle fungus on roots

Climate and Average Temperatures

Average monthly temperature figures can have a significant impact on black winter truffle cultivation. As a general guide, seasons need to be clearly defined, but not characterized by extremes.

The typical average temperatures for the coldest month in natural truffle areas are between 35-45 degrees Fahrenheit. We believe that areas with warmer winters can be productive as long as the evening temperature falls significantly and light frosts are not uncommon. However, significant and extended freezing of the soil to the depth of the truffles can severely impact the harvest by damaging the fruits. Therefore, areas with very low winter temperatures should be avoided. Visit our interactive map that shows locations with suitable temperatures for the Périgord black truffle.​

Truffle orchards require sunlight penetration of the canopy and warm soil temperatures to aid development of the fruiting body over the summer months. Typical average temperatures for the warmest months within production areas range between 62-74 degrees Fahrenheit. High summer temperatures may be managed with mulching, tree densities, row-orientation and irrigation. Visit our interactive map that shows locations with suitable temperatures for the Périgord black truffle.​

Rainfall

Rainfall can have a significant impact on truffle yields. In Europe, seasonal rainfall is usually the biggest factor influencing the annual truffle yield, and the same applies to North America.

The winter months are the time of year when truffles are in their final ripening stages. Prolonged and heavy rainfall during this period can severely impact on the harvest. Saturated and stagnated ground will cause the truffles to rot before they can be harvested. This is particularly a problem of heavy soils, such as those with high clay content. In areas of high winter rainfall, heavy soils must be avoided and sites with a free draining soil should be used to help mitigate the impact of heavy and prolonged precipitation.

This is perhaps the most important factor influencing yields. The truffle requires spring/summer storms to initiate fruiting. The rainstorm can be effectively simulated by heavily irrigating over a short period of time. During the summer the truffles will continue to grow and swell, and for this they require moisture. Severe summer drought has a serious impact on yields. In particularly dry areas, the truffles will require a small amount of irrigation to ensure maximum yields.

Because of the uncertainty of natural rainfall, we strongly recommend partner orchards to be irrigated. ATC has done extensive research into irrigation and can recommend a system that complies to our strict scientific criteria.

Soil Conditions

The ideal soil for truffle cultivation is free-draining with a pH of between 7.6 – 7.9. At the high pH levels, the availability of certain key nutrients needed for truffle cultivation can be limited, therefore a comprehensive soil test need to be performed to identify possible nutrient deficiencies.

Soil pH is among the more than a dozen soil elements to manage, and can be altered by agricultural liming. ATC has extensive experience in amending soil and has successfully increased pH on fields as low as 4.5.

Heavier soils can be utilized if they are managed correctly. Typically heavier soils can impede water drainage and create physical resistance to individual truffle’s formation. But if they are managed correctly, both of these can be overcome.

Other factors

Aside from climatic and soil conditions, there are a number of other factors that need to be addressed when choosing a truffle orchard site:

Truffles need free-draining soil in order to thrive, therefore, drainage is an important consideration if your land tends to be waterlogged during rainfall.

Aspect, or direction of exposure, can be an important factor for truffle production. In France, many existing truffle orchards have a southern aspect because of the amount of sun it provides. However, a number of other factors, including prevailing wind direction, can also have an impact on the exact aspect that is favorable for truffle production in your region. Many successful truffle orchards are, in fact, on flat land. The key consideration when it comes to land is that it should not be too hilly, as you will need to drive equipment on the land.

Trees that harbor competing mycorrhiza species must be avoided and separated from the truffle trees either through a physical barrier or distance.