Research Outline

USDA THC Testing Guidelines


For states that grew hemp in 2018, identify their rate of failure for hemp samples testing above the 0.3% THC concentrate limit.

Early Findings

North Carolina

  • In 2017, 135 hemp samples were tested within the state and 14 tested above 0.3% THC
  • In 2018, about 400 samples were tested and 38 came back positive.
  • Thus, around 10% of samples are testing as "hot hemp," the term used to describe hemp over the 0.3% limit.


  • The average rate of failure by testing over 0.3% THC for hemp samples in Colorado is 30%.


  • Washington State was using a different process to test hemp up until October 31, 2019. The state tested the entire plant, instead of just a top clipping like other states do. With testing the entire plant, state officials said virtually everyone passed. One sample did fail, but was retested at a different lab and passed.
  • Farmers in Washington are concerned that more people will fail with the new rules, which also decrease the testing time frame from 30 days prior to harvest to 15 days.