The growing of low-THC Cannabis sativa L. (hemp) in the U.S. has recently been federally legalized after nearly 50 years of being listed as a Schedule I drug. Since the passing of the 2018 Farm Bill which moved cannabis with no more than 0.3% Δ-9 THC off the Schedule I substances list, there has been a growing need from the industry for researchers to fill the crop production knowledge gap with studies analyzing crop physiology, cannabinoid extraction techniques, pest management strategies, etc. Some companies looking to supply horticultural lights to growers are promoting claims that haven’t been vetted scientifically. Additionally, many cultivators are choosing to grow Cannabis sativa L. in controlled environments. Controlled environment production can be preferable with multiple harvests per year, greater environmental control, optimized labor management, and greater quality control to name a few benefits. However, controlled environment production of cannabis is a large consumer of energy and source of carbon dioxide emissions from systems designed to maintain optimal growing conditions. In chapter 1, I sought to understand the impact of far-red light (700- 800 nm) on plant morphology, photosynthesis, yield, and cannabinoid concentration. In experiment 1.1, I experimented with growing two hemp cultivars at the flowering stage while substituting 10% of photosynthetic photons (PAR; 400-700 nm) with far-red photons. The results revealed significant increases in plant height, reduction in stem diameter, and a reduced flower dry weight with increased far-red. Experiment 1.2 was conducted at the vegetative stage with a supplemental far-red light gradient under a background of white light. As the gradient increased, plant height, stem dry weight, and leaf dry weight increased. Also, leaf level photosynthesis measurements were taken and showed that ‘Janet’s G’ had a higher rate of photosynthesis under lower far-red percentages than at the highest, whereas ‘TJ’ had a higher rate of photosynthesis under the highest far-red percentage. In experiment 1.3, I applied the same far-red gradient in experiment 1.2 under a background of white light for a three-week vegetative period but turned off the far-red light for the whole flowering period. The only significant result was an increase in plant height for cultivar ‘TJ’. In chapter 2, I experimented with growing three day-neutral CBD hemp cultivars under increasing supplemental light intensities with daily light integral (DLI) varying from 15 to 30 mol m-2 d-1 in experiment 2.1 and 17.8 to 35.1 mol m-2 d-1 in experiment 2.2. The day-neutral cultivars used in both experiments yielded increasing whole plant fresh weight, dry weight, and flower dry weights under increased DLI. Cannabinoid concentrations varied and were inconsistent between the two experiments. In conclusion, far-red light leads to taller plants, decreased stem diameter, lower flower dry weights, and the degree of the response can be cultivar specific. Overall, I did not find practical benefits of adding more than 2-3% far-red under sole-source lighting. For day-neutral hemp cultivars, higher DLI is beneficial in facilitating increased plant and flower biomass accumulation. More work is needed to investigate the point of diminishing returns of DLI for day-neutral cannabis (both crop physiology and economic) and evaluate the effect longwave radiation from HPS lights has on plant growth.