USDA Releases Final Rule on Hemp Cultivation The U.S. Department of Agriculture has released its final rule governing the cultivation of hemp, which will take effect March 22, 2021. The draft rule would have required hemp to be shown to contain less than 0.3% tetrahydrocannibanol (THC) on testing conducted within 15 days of harvest, a proposal that drew criticism from several parties. The final rule reduces some of the requirements, such as allowing 30 days to test and raising the negligence threshold to 1% rather than 0.5%. The rule also allows some flexibility for states to develop testing methods that take into account variables such as regional environmental factors.