Waterleaf (Talinum triangulare) is one of the most important indigenous leafy vegetables cultivated in tropical Africa because of its rapid growth, high nutritional value, and economic importance. However, productivity and nutritional quality are often constrained by poor agronomic practices, particularly inappropriate plant spacing and inadequate soil fertility management. This study evaluated the effects of different plant spacing and organic manure rates on the growth, yield, and nutrient composition of waterleaf under field conditions. The experiment was conducted using a factorial arrangement in a Randomized Complete Block Design (RCBD) with three replications. Three plant spacing levels (20 × 20 cm, 30 × 20 cm, and 40 × 20 cm) were combined with three poultry manure rates (0, 5, and 10 t ha⁻¹), resulting in nine treatment combinations. Growth parameters, including plant height, number of leaves, stem diameter, and leaf area, were measured periodically, while fresh yield and dry matter yield were determined at harvest. Proximate analyses were conducted to determine moisture, crude protein, crude fibre, ash, fat, carbohydrate, and selected mineral contents using standard analytical procedures. Data were subjected to analysis of variance (ANOVA), and treatment means were separated using Duncan's Multiple Range Test at the 5% probability level. The findings demonstrated that both plant spacing and organic manure significantly influenced vegetative growth, biomass production, marketable yield, and nutrient composition of waterleaf. The combined application of moderate plant spacing with higher organic manure rates consistently produced superior agronomic performance and improved nutritional quality. The study concludes that optimizing plant spacing together with appropriate organic manure application provides an environmentally sustainable strategy for enhancing waterleaf productivity while improving its nutritional value for consumers.