Maize (Zea mays L.) is a critical food and cash crop in Sierra Leone, yet national yields remain far below potential, partly due to reliance on non-standardized plant spacing practices among smallholder farmers. This study evaluated the effect of four plant spacing arrangements, viz: T1 (75 cm × 25 cm), T2 (60 cm × 30 cm), T3 (50 cm × 25 cm), and T4 (35 cm × 35 cm, control) to explore on the vegetative growth, yield components, and grain yield of maize at the Faculty of Agriculture Experimental Farm, Ernest Bai Koroma University of Science and Technology, Makeni, Bombali District, Sierra Leone. A Randomized Complete Block Design (RCBD) with four replications was used, and treatment means were compared using the Least Significant Difference (LSD) test at the 5% probability level.

Results showed that plant height and Leaf Area Index (LAI) were significantly higher under narrower spacing (T3 and T4), with the control producing the tallest plants (158.8 cm) and highest mean LAI (5.10), while whole plant weight showed no consistent density-dependent pattern. Individual ear-level traits – ear length, kernel row number, ear wet weight, and 1000-grain mass – were consistently superior under wider spacing (T1 and T2), reflecting reduced inter-plant competition. However, grain yield followed the opposite trend: the denser treatments (T3 and T4) significantly outyielded the wider-spaced treatments by 42–45%, achieving 5,420–5,440 kg/ha compared with 3,750–3,830 kg/ha, demonstrating that greater plant population per unit area compensated for smaller individual ears.

The study concludes that total plant population, rather than row-to-intra-row geometry, was the primary determinant of both canopy development and final grain yield. Closer, equidistant spacing (50 cm × 25 cm or 35 cm × 35 cm) is recommended for maximizing grain yield per hectare, while wider spacing remains preferable where individual ear size and grain quality are prioritized, such as for fresh-market or premium-grain production.