Hot summer temperatures and cold winter temperatures.
Since truffles grow in a symbiotic relationship with trees, the grower not only needs to think of the safety of his truffles, but the trees as well. The Martins have been able to protect their trees from pest and disease damage using preventative and natural methods. How to grow truffles. David Cassford wanted to do something with his 11 acres besides mow it. As a native to the Isle of Wight, he has a particular fondness for the filbert nut. Thinking he might like to plant a grove of filbert trees, he researched them online — and discovered truffles. Truffles are a member of the tuber family of mushrooms with an earthy flavor that is reminiscent of a cross between garlic and mushrooms. They grow underground among the roots of various trees, including hazelnut, chestnut, pine, willow, elm and oak trees. Truffles are grown primarily in the wild-mainly in France, Croatia, Italy, Oregon and Washington. Truffles are the underground fruiting bodies of some fungal species. They require particular climate conditions and soil types as well as suitable hosts in order to thrive. Truffles establish a symbiotic relationship with the roots of host trees, with each party receiving nutrients or minerals more efficiently through the relationship. Truffles grow in a symbiotic (give-and-take) relationship on the roots of trees — particularly filbert and certain species of oak. “When the trees are dormant in the winter,” says Cassford, “the truffles take their nutrition from them. How to grow truffles. David Cassford wanted to do something with his 11 acres besides mow it. As a native to the Isle of Wight, he has a particular fondness for the filbert nut. Thinking he might like to plant a grove of filbert trees, he researched them online — and discovered truffles. Conditions Necessary for Growing Truffles. When planting the treated seeds or seedlings, it is necessary to choose a location that is: 1  Away from extreme weather conditions-This is why the temperate climate of the Pacific Northwest is an ideal location for truffle hunters. They grow underground among the roots of various trees, including hazelnut, chestnut, pine, willow, elm and oak trees. Truffles are grown primarily in the wild-mainly in France, Croatia, Italy, Oregon and Washington. Climate. Truffles are found wild throughout the world and are highly prized by chefs. Due to their high value they are now extensively cultivated throughout much of the world, including Australia, New Zealand, the United Kingdom, the United States and Europe. They require particular climate conditions and soil types as well as suitable hosts in order to thrive. Truffles establish a symbiotic relationship with the roots of host trees, with each party receiving nutrients or minerals more efficiently through the relationship. Growing Truffles. For many it is a dream to grow the mystical, rare and delicate fungi with the most arresting aroma in the culinary world. And for those who have taken the plunge, once they find their first truffle, this dream easily becomes an obsession and a passion. Climate. Truffle production requires hot summer temperatures and cold winter temperatures and climate is probably the primary issue. As a general rule, a mean daily temp of about 20 degrees in the January and mean daily of about 5 degrees in July is desirable. What to do while Growing Truffles. Plant your specially inoculated seeds or seedlings in an area with well-drained soil. Keep other plants, vegetation and trees from encroaching on the area where the hazelnut tree seeds have been planted. Wait and watch. They grow underground among the roots of various trees, including hazelnut, chestnut, pine, willow, elm and oak trees. Truffles are grown primarily in the wild-mainly in France, Croatia, Italy, Oregon and Washington. Truffles only grow on certain types of trees, including oak, hazel, poplar, beech and pine. The challenge in growing significant quantities of truffles is that you need to grow both the tree and the fungus—and you need them to cooperate with each other while a whole zoo of other microbes lurks in the soil.  Close up views of mycorrhiza. Truffles are a fungus that can only survive by attaching itself in a mutually beneficial way to certain types of tree roots in what is called a symbiotic relationship. The resulting combination of fungus, roots and other select organisms form a structure called mycorrhiza. 
http://www.grit.com/farm-and-garden/crops/how-to-grow-truffles-zm0z14mjzsin.aspx http://gourmet.lovetoknow.com/Growing_Truffles http://www.ehow.com/list_7433323_requirements-growing-truffles.html http://www.grit.com/farm-and-garden/crops/how-to-grow-truffles-zm0z14mjzsin.aspx http://gourmet.lovetoknow.com/Growing_Truffles http://www.ehow.com/list_7433323_requirements-growing-truffles.html http://trufflegrowers.com.au/growing-truffles/ http://gourmet.lovetoknow.com/Growing_Truffles http://www.bostonmagazine.com/restaurants/blog/2013/12/05/chefology-truffles-demystified/ http://www.garlandtruffles.com/trufflegrowingbasics.html
what kind of climate do truffles grow in