Can long photoperiods be utilized to integrate Cichorium spinosum L. into vertical farms?

Vertical farming is gaining attention for urban agriculture and sustainable food production, but mainstream crops may not be economically viable in this system, prompting a shift to high-value crops. This study explores the potential of Cichorium spinosum L. (spiny chicory), a wild edible green, for vertical farming. When cultivated on open field and greenhouses, spiny chicory tends to flower prior vernalization deeming the flowered plants unsalable, necessitating an investigation on its flowering responses. C. spinosum L. plants were cultivated and for 5 months in peat-filled pots, under low light (100 umols m² s^-1), and two photoperiods (10 and 15 hours) with stable temperature (20°C) and CO2 level (400 ppm). No flowering occurred at the end of the first experiment, indicating that photoperiod alone did not induce flowering. Next, C. spinosum L. was hydroponically cultivated in a commercial vertical farm with a 15-hour photoperiod, light intensity of 300 umols m^-2s^-1, temperature between 25 and 30°C, CO2 levels of 350 to 400 ppm, and plant density of 100 plants m^-2. At the end of the one-month cultivation, gas exchange measurements were conducted to analyze CO₂ uptake and evaporation, whereas the salable fresh weight was approximately 1.7-2 kg per m². This study aims to enhance understanding of spiny chicory’s flowering response and growth performance, providing valuable insights for cultivating this wild edible vegetable in vertical farming systems.