Sustainable Star? The Carbon Footprint of Christmas Stars and Its Variability along the Value Chain

Although greenhouse production is an especially intensive form of agricultural production, horticultural products have not been subject to many carbon footprint studies. This study examines the poinsettia, a relevant greenhouse plant in the market. It analyzes the poinsettia’s climate impact by undertaking a product carbon footprint (PCF) study, along the whole poinsettia value chain; this starts at the mother-plant farms in Uganda, goes through the production in German greenhouses, and ends with the disposal of the plant by the consumer. A life cycle inventory was conducted, including input materials, equipment, cultural practices, and other processes used in two horticultural farms. A standardized questionnaire collected consumer data. The PCF for the poinsettia is 0.69 kg of carbon dioxide equivalent (kg of CO2e), including distribution. As heating in both investigated farms is conducted via renewable energy, major contributors to the PCF were overhead electricity, substrate, pot, and packaging. The consumers’ contribution varies from 0.31 (best), through 0.45 (average), to 1.49 (worst) kg of CO2e, and is mostly due to differences in shopping behavior, producing a total PCF of 1.0–2.18 kg of CO2e. The results show a high variability for emissions along the value chain, due to different input factor choices on the production side and a significant consumer contribution.