virgin soil

noun

soil that has not been cultivated before
a person or thing that is as yet undeveloped

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Examples from the Web for virgin soil

Historical Examples of virgin soil

Something assured me that her heart was virgin-soil, that the flower of romantic affection had never bloomed there.
A Passionate Pilgrim
Henry James