Coleus foliar nutrient sufficiency ranges and growth response to nitrogen concentrations

Three coleus (Plectranthus scutellarioides) cultivars were grown with one of five constant liquid fertilizer concentrations (75, 100, 200, 300, or 400 mg L^‑1 N) using a 13N-0.86P-10.8K fertilizer. The cultivars used were ‘Broad Street’, ‘Stained Glassworks Eruption’, and ‘Wall Street’. Tissue samples were collected and analyzed for concentrations of nutrient concentrations at two different times. At each harvest date, plant height, plant diameter, and shoot dry weight were recorded. Each cultivar achieved maximum growth when grown with ≤300 mg L^‑1 N, while 400 mg L^‑1 N was detrimental. Foliar nutrient sufficiency ranges were determined based on fertilizer concentrations resulting in maximum growth for each cultivar. These results provide improved coleus fertilization recommendations and foliar sufficiency ranges.