With the passage of the Agricultural Improvement Act of 2018 (2018 Farm Bill), the legally allowable limit of total THC in harvested hemp is 0.3%. With timely harvest and proper watering and fertilization methods, this should not be an issue. The conversion rate is (THCA x .877) + Delta-9 THC = Total THC. Lab results can sometimes be highly variable. Please be sure to choose a reliable and consistent accredited lab to work with so that you can be assured of the THC levels throughout the season. It is recommended that you begin testing your field 2 weeks into the flowering cycle every 1-2 weeks until harvest so that you are very familiar with where your THC levels are at.
Most of the hemp grown for CBD oil production in the US is grown for “biomass” to be processed into high CBD crude, distillate, and isolate forms of CBD extract. This material can be comprised of flower, water leaf, stems, and sometimes stalk material when milled. The CBD levels of this product is on average 30-50% lower than the trimmed flower may be. Responsible harvesting methods still come into play to ensure a compliant harvest, yet there is less concern of going over the legal total THC limit when farming for a biomass product as compared with trimmed flower sold in bulk or processed down into pre-roll form. This is the challenge of the flower farmer, to harvest a quality end product and stay below the legal Total THC limit when combining THCA and Delta-9.
During the last few years of hemp farming in early adopter states, farmers have managed to work with and overcome these challenges. There are several variables that may affect the CBD to THC ratio in the final harvest. One thing is certain, healthy plants and healthy soil can help prevent stress-induced THC spikes. There have also been some encouraging reports of using a streptomyces dominant microbial formulation to increase CBD levels in the plant, which may in turn also reduce the THC levels. For this reason, we are highly recommending this biological amendment to be applied during the season which has also been shown to increase terpene production. Beyond these outstanding benefits, the addition of the biology will work to improve your soil over time.