Pentas growth response to nitrogen concentrations

Three pentas (Pentas lanceolata) cultivars ‘Butterfly Sweet Pink’, ‘Graffiti Violet, and ‘New Look White’ were grown with one of five continual liquid fertilizer concentrations (75, 100, 200, 300, or 400 mg L^‑1 N) using a 13N-0.86P-10.8K fertilizer. Tissue samples were collected and analyzed for the concentration of 13 elemental nutrients after four weeks of growth and upon termination of the study (6 weeks). At each harvest date, plant height (measured from the pot rim to the uppermost part of the plant), plant diameter (measured at the widest dimension, turned 90°, and averaged), and shoot dry weight were recorded. Based on the evaluation of the plant growth index, optimal fertility levels of 75 to 200 mg L^‑1 N provided the greatest effect. The corresponding leaf tissue nutrient concentrations for pentas are the first source of recommended values available to the floriculture industry.