Abstract
Optimizing plant density and vegetative growth duration is important for improving productivity in controlled-environment medicinal cannabis cultivation. Although both factors strongly influence canopy development and yield, their combined effects under modern high-intensity LED lighting, and particularly their consequences for cannabinoid uniformity across the canopy, remain insufficiently characterized. This study examined how planting density and vegetative duration influence plant growth, yield, and cannabinoid concentration in Cannabis sativa L. (strain ‘Fat Banana’) grown under controlled environment conditions, high-intensity LED lighting and precision fertigation. Two vegetative durations (10 and 28 days) were evaluated in separate but identical controlled-environment chambers under broad-spectrum high-intensity LED lighting and automated precision fertigation on rockwool substrate. The 10-day regime compared 8, 14 and 18 plants m−2; the 28-day regime compared 6, 8 and 10 plants m−2. Each combination was replicated across two independent cultivation cycles, and because density levels differed between regimes, direct between-regime comparisons were restricted to the shared density of 8 plants m−2. Extending the vegetative phase from 10 to 28 days increased plant height, stem diameter and internodal length. Area-based yield increased strongly with density, reaching 1091 g m−2 at 18 plants m−2 under the 10-day regime and 1009 g m−2 at 10 plants m−2 under the 28-day regime. Apical biomass exceeded basal biomass, but total THC concentration did not differ significantly among planting densities, vegetative durations or canopy positions. Higher planting densities combined with shorter vegetative periods can therefore increase area-based productivity while maintaining stable THC concentration under high-intensity LED cultivation.
