A definition of the range of temperatures suitable for all varieties.
While we don’t have scientific provable data (yet) about the requirement for truffle production for winter cold and only moderate summer heat, looking at the areas where they are growing gives us our preferred climatic range. But like all historical ‘averages’ that haven’t been updated to encompass the recent warming trend, this will change the zones we have previously recommended. Remember, altitude changes can make a specific site very cooler in both summer and winter.
These top maps use data from 1961 to 1990, a 30 year span. The second map shows that there was a 0.2 -0.3°C degree warming in winters from 2007-2015. If you need to see what the changes in climate will mean to your selected region we encourage you to visit the CSIRO Climate Changes site and use their Threshold Calculator . There’s an example below showing the modelled changes in East coast winter, as May frost days, but you can also see each month and get a feel for how hot your area will be by the time you reach full production in ten to fifteen years.
This is what information we’ve been using historically
What we need to consider
What those climate changes will mean
This (static) example of the online tool on the CSIRO Climate Changes site. It shows the historical data for Frost days in May (below 0°) and Threshold changes predicted 2016-2045 (when your new plantation will reach maturity). You will find be able to drill down to your region in the CSIRO site. This is example of ‘Frost Days’ is included because East Coast growers report that it takes the first few days of frost to precipitate the maturing of their truffle. Given that the West Australian growers have almost no frost and produce at a similar time, this may just be a matter of waiting later in the cooler Eastern areas for the production to start (and accepting more rot with the trend to warmer winters).
The above screen captures are from the Bureau of Meteorology July 2016