In the face of agricultural labor shortages, reducing labor and costs in rice production while meeting demand or increasing yield is crucial for sustainable agricultural development.  Using crop straw boards and raising seedlings at a high-density can reduce labor demand and enhance rice yield.  This study investigated the effects of seeding density and transplanting age on tillering patterns, panicle formation rates, and yield to determine the optimal cultivation practices for maximizing rice yield.  Two-year field experiments were conducted in Sihong County, Jiangsu Province, China, using the japonica rice variety Nanjing 5718.  Five seeding densities (150–350 g/tray) and four transplanting ages (10–25 days) were evaluated to assess their impacts on tillering patterns, panicle formation rates, and yield.  Innovative crop straw boards were employed to enhance planting efficiency and reduce dependence on soil for raising seedlings.  This approach also lessened tillage layer destruction, promoting sustainable practices.  The results indicated that increasing seeding density significantly altered tillering and panicle formation patterns by reducing the occurrence and panicle formation rates of lower-position tillers.  Although the occurrence of middle- and high-position tillers increased, the overall number of panicles per hill decreased, especially at higher densities, negatively affecting yield.  Reducing the transplanting age promoted the emergence and panicle formation of lower-position tillers, thus mitigating these negative effects.  Specifically, compared to traditional methods (150 g/tray, 20-day seedlings), the higher seeding density (300 g/tray) and reduced transplanting age (15-day seedlings) increased total panicle number by 3.79–4.73% and yield by 3.38–5.05%.  Combining higher seeding densities with reduced transplanting ages offers significant advantages over conventional practices by enhancing resource utilization and improving tillering efficiency.  These findings provide actionable recommendations for optimizing rice cultivation practices and contribute to sustainable agricultural development.