Lighting Strategies for Indoor Cannabis Propagation, Vegetative Growth, and Flower Initiation

Abstract

The cannabis industry is rapidly growing, but there is a lack of scientific research for optimal lighting regimes throughout the growth cycle. This thesis explored the effects of light spectrum, intensity, and photoperiod on indoor cannabis cultivation at three different stages. Results showed that cuttings rooted under fluorescent and different light-emitting diode combinations had no effect on rooting performance during the 14-d propagation stage or on growth attributes post-transplant. During the vegetative stage, cannabis plant morphology is subjective to cultivators, but light intensities of 500-600 µmol·m-2·s-1 can be used to achieve taller plants to increase airflow, or 900-1000 µmol·m-2·s-1 can be used to achieve shorter, more compact plants for structural integrity. In vitro cannabis explants need at least 10.8 h uninterrupted dark period for floral initiation. This thesis provides useful information for cultivators to improve production by utilizing the versatility of light-emitting diodes throughout the growth cycle.