Floriculture makes up the largest sector of ornamental horticulture production, valued at $6.7 billion and dominated by the production of annual bedding-plants. Production is timed to meet spring market dates, starting during a time of year when ambient outdoor temperatures and daily light integrals are below optimal for high-quality plant production. As a result, heating and supplemental lighting can represent a significant operational and energy cost for producers. Yet, producers and investors of the industry have acknowledged an inability to evaluate their resource use due to a lack of industry-wide benchmarks and key performance indicators (KPIs). Past research has compiled energy and water data from controlled environment agriculture (CEA) and, for floriculture, investigated the potential of energy-efficient production strategies and used life cycle assessments (LCAs) to evaluate the environmental impact of the products produced. However, CEA focuses on food production and both the compiled CEA data and the LCAs are largely based off modeled data. Therefore, this research will validate models utilized in LCAs and carbon footprint studies with experimental data, giving producers additional benchmarks and KPIs to evaluate their operational resource-use efficiency. The objectives of this study were to (1) evaluate the use of supplemental day-extension lighting (SDEL) from two different fixtures [(light-emitting diodes (LEDs) and high-pressure sodium (HPS)] during unrooted cutting (URC) propagation of five annual bedding plants and (2) to quantify the greenhouse energy and water consumption. Unrooted cuttings were received from a commercial propagator and stuck in a 105- (calibrachoa, coleus, impatiens, and petunia) or 72- (geranium) propagation tray filled with a pre-moistened soilless propagation substrate and placed under oner of three SDEL treatments on root-zone heating set to 23℃. Each treatment consisted of a propagation tent for callusing and an adjacent rooting environment. Until adventitious root formation, cuttings were misted with clear water, and then were removed from the propagation tent where they were irrigated daily with 150 mg·L–1 nitrogen provided by 15-5-15 water-soluble fertilizer (JR Peters, Inc.; Allentown, PA). After 21 days, data were collected on rooted cuttings. As expected, the energy-use of HPS-lamps exceed that of the LEDs. However, cutting stem-length and stem and leaf dry mass were decreased under SDEL, resulting in liners that were more compact, uniform, and of higher quality than those propagated under ambient conditions. An opposite trend was observed for root dry mass. This indicates that SDEL is a critical tool when utilized for bedding-plant propagation.
