## 1 Introduction  
United States federal and state laws in recent years have resulted in changes in legal restrictions and definitions of _Cannabis sativa_. Additionally, the consumer and markets have observed a surge of interest in the growing, processing, selling, and using of products containing cannabidiol (CBD), derived from hemp flowers. Hemp is legally defined as _C. sativa_ strains with a tetrahydroocannabinol (THC) concentration no greater than 0.3% in any part of the plant (Congress [1,2]). _C. sativa_ strains with a THC concentration greater than 0.3% in any part of the plant are considered marijuana and have varying restrictions in legality, distribution, and consumption. High CBD _C. sativa_ (hemp) contains over 100 cannabinoids, which include THC, CBD, and cannabigerol (CBG), in varying forms. It is well known that THC has psychoactive effects and has thus resulted in its controversial legal standing. Many health benefits from certain cannabinoids, such as CBD, have been reported. The benefits of CBD have gained popular support due to these health discoveries and the non-psychoactive effects that drug-type cannabis can produce due to low levels of THC. Hemp has historically been grown for its fiber and seed. The changes in legislation, have recently resulted in a market for flowers and flower derived distillates. Hemp grown for flowers ( floral hemp)follows a horticultural production model either in a greenhouse or bedded field compared to fiber and seed hep, which follows an agronomic production model. Due to the previously illicit nature of _C sativa_, there is little published research investigating the cultural and production needs of this crop. One of the most limiting factors to obtaining optimal yield is mineral nutrient supply. Given the economic portion of industrial hep can be the floral material or seeds, phosphorus (P), and other fertilizers are vital for proper plant development and the production of primary and secondary metabolites ([PERSON] [3]). It is also known that nitrogen (N) fertility plays an important part in the production of THC in _C. sativa_ ([PERSON] et al. [4]). Very little work has been done in optimal nutrient needs for _C. sativa_ in protected environments. The impacts of N, P, and potassium (K) were studied in greenhouse produced _C. sativa_; however, these results only explored a few widely distributed interval concentrations and were completed in soil culture rather than a soilless substrate ([PERSON] et al. [5]). Critical leaf tissue nutrient ranges have been established for all macro and micronutrients ([PERSON] et al. [6]). This work found that, with a modified [PERSON]'s solution regime, _C. sativa_ \"T-1\" plants accumulated 0.43% P in most recently matured leaf tissue with regard to foliage dry weight. Plants grown without P contained 0.09% leaf tissue concentrations. Additionally, a survey of multiple _C. sativa_ high CBD cultivars reported an average leaf tissue value of 0.35% P with vegetative mother stock plants ([PERSON] et al. [7]). Work completed by [PERSON] et al. [8] showed that 56 days after planting, macronutrient concentrations in floral portions of fiber varieties started increasing. This study also indicated that seed formation resulted in a huge demand for P resources, and floral material required large N and K resources as well. These works reported that severe limits to growth and yield are encountered when P resources were limited. From prior work, the general survey range for leaf tissue fertility levels were reported, and the lower deficiency ranges were present for _C. sativa_ plants grown in the greenhouse ([PERSON] et al. [7]). Nutrient and accumulation and partitioning were tracked with fiber varieties in the field ([PERSON] et al. [8]). However, no research has been completed on the optimal P concentration for greenhouse-grown hep. To this end, this study examined the optimal fertility concentrations for were tested utilizing six concentrations.