What are truffles?
A truffle is an underground fungus usually found in close association with certain species of tree. The fine threads of the mycelium are attached to the roots extending their reach and taking up water and nutrients to pass to the tree. In exchange the tree gives the fungus carbohydrates. This is an example of a symbiotic relationship; in the fungus world it is a mycorrhizal relationship.
Many truffles are rare, edible and as they are considered to be delicacies, are among the world's most expensive foods. There are dozens of different species, but the best species can cost over €10,000 / kilogram. A single white truffle was once sold for £165,000!
Why grow truffles?
Prior to World War I, the global annual truffle yield was about 600 tonnes / year. It has now plummeted to just 30. Supply and demand is the reason for the high price of truffles. Now, around 70% of truffles are produced under cultivation in truffle plantations or orchards. These are found across the globe, in North and South America, South Africa, Australasia and Europe, including in the UK. Prices of truffles will vary with species and supply / demand but species that can be grown in the UK can command prices of over £500 / kilogram.
Are there different species of truffle?
There are hundreds of truffle-like species (fungi growing underground) around the globe. However, only a dozen or so are worth eating. Edible truffles are described in terms of their skin colour – black or white. The two best known (and valuable) species are the Périgord Black or Winter truffle (Tuber melansporum) and the Italian White truffle (Tuber magnatum). The former can be cultivated if your climate is warm enough. Suitable countries in Europe include Spain, France and Italy. The Italian White has not been successfully cultivated. For cooler climates, such as that of the UK, there are other, slightly less-valuable species of truffle that can be cultivated.
Which species of truffle should I grow?
It is your climate that determines this. The Black Summer (Burgundy) truffle (Tuber aestivum var uncinatum
) is found growing naturally in many European countries, from Ireland to the Balkans, from Portugal to Southern Sweden. The Whitish (Bianchetto) truffle (Tuber borchii
) can grow in areas with the same climate. You need a Mediterranean-like climate for the Black Périgord (Winter) Truffle; they will not grow in cooler climates like the UK.
If you unsure about your climate and which species of truffles would grow there, see this link. Note, Summer truffle is called Burgundy there. You will need to track down climate parameters for your area, but general figures can usually be found on-line.
Yesterday, it was reported in the media (e.g. The Daily Telegraph) that the Mediterranean black Périgord truffle, also known as the winter truffle, has been successfully cultivated in the UK. One of these truffles was harvested from an inoculated Turkey (Holly / Evergreen) Oak planted in 2008 in South Wales. Previously it was thought that a warmer, Mediterranean climate, such as that found in Southern France, Italy, Croatia, Slovenia, Spain etc was required.
This cultivation has shown that the climatic tolerance of this species of truffles is much broader than previously thought, but it’s likely that it’s only possible because of climate change, and some areas of the UK are now suitable for the cultivation of this species.
Further investigation is required into mapping the climate parameters but it appears that growing Périgord truffles will certainly be possible for some areas of the UK in the future.
How long does it take to grow truffles?
If you are successful in growing truffles, they generally appear earlier on Hazels after 5 - 8 years from planting. For Oaks, it is more likely to be 10 years.
If I want to grow truffles what do I actually plant?
The starting point is young trees, approximately a year old. At this age, a hazel is approximately a metre tall, an English Oak is approximately 30 centimetres tall. These have been “inoculated” or “infected” with the truffle fungus. This is done in a laboratory under carefully controlled conditions. They are then grown on in sealed polytunnels to avoid the risk of contamination by competing fungi spores that are in the air.
Are grants available for truffle plantations?
The situation regarding grants for tree planting changes over time and will be different from country to country. This Woodland Trust web page
is a good source of information on grants and funding
for tree planting in the UK.
What site requirements are there?
You will require vehicular access to the site to apply lime, mow etc. so it should not be too steep. The site should be separated from existing woodland that might be a source of competing fungi.
What site preparation is needed?
It is preferable that a site has not had trees growing on it before. Soils should be tested and corrected for serious nutrient deficiencies and imbalances prior to planting. We will work with you to determine what soil amendments are needed, if any. It may be necessary to apply and incorporate lime to raise the soil pH. The land will need ploughing and a seed bed preparing. We would recommend fencing the site to keep animals out.
What is the planting density?
There are different light / shade requirements for different truffle species. In general, trees inoculated with the Périgord truffle are planted at a lower density than the shade-loving Summer truffle. We recommend 500 per hectare for Périgord and 1600 trees per hectare for Summer truffle.
When should I plant the trees?
The best time to plant them is in the dormant period between November and March. If the ground is frozen or waterlogged it is better to wait until conditions improve.
What soil do I need?
The ideal soil for growing truffles has not been compacted, is well drained and alkaline (not acidic). pH is a measure of soil acidity. The ideal pH for the Summer Truffle is 7.3 – 8.0; for Périgord (Winter) black truffles it is 7.5 – 8.3. If your pH is too low, then it can be increased by applying agricultural lime to the planting site. There are successful truffle plantations on naturally acidic soils that have had lime added. We can advise on soil sampling and testing your soil to determine liming requirements.
What on-going maintenance is required?
Once the trees are established, the ongoing maintenance tasks in a truffle orchard may include irrigation, weed control (mowing, mulching and / or spraying), pruning, removal of leaf litter and possibly topping up the lime. This is less than for a vineyard.
Do I need to irrigate the trees?
It will depend upon your climate and site. Generally, in the UK, it is not needed, though exceptional weather in the first two years may make it necessary.
Harvesting is undertaken with specially trained dogs. This causes the minimum disruption to the fungus and means only ripe truffles are harvested. Companies such as ours, The English Truffle Company, can provide dog teams, and sell the truffles on your behalf or let you do so. We can also help train your own dog.
Will I get Hazel nuts from inoculated Hazel truffle trees?
The hazel will produce a small crop of nuts and can also be coppiced (variety is Kentish Cob). The hazelnut harvest will be lower than for commercial nut orchard as the soils are optimised to benefit the truffle which has different needs to that of nuts.
Am I guaranteed to get truffles?
No. The trees are all certified as being inoculated with the truffle fungus. They will, however, only produce truffles under optimum conditions. If the tree remains healthy, is watered and the soil conditions are right then you may produce truffles.
What are the likely yields and risks?
Truffle growing is not a “get rich quick” activity. It should be considered as a long-term investment, that may or may not yield any returns, much the same as other agricultural pursuits. Estimates of yield vary with tree age but for Summer truffles are in the range 11 kilograms per hectare at the beginning of production to nearly 250 kilograms per hectare after 5 years of production. For Périgord truffles with lower planting densities, these figures are estimated to be 4 - 90 kilograms. Wholesale prices at peak can be £500 / kilogram for Summer truffles and £850 / kilogram for Périgord truffles.
Any information or advice provided is based on the most up-to-date information available to The English Truffle Company at the time of writing. All due care was exercised in its preparation. Any action taken in response to this information is the sole decision of the user of the information and is taken at his or her own risk. Accordingly, The English Truffle Company disclaims any liability whatsoever in respect of any losses or damages arising out of the use of this information or in respect of any actions taken in reliance upon the validity of the information.