This study evaluates environmentally friendly methods for controlling weedy rice (Oryza sativa f. spontanea) to reduce reliance on chemical herbicides. Extracts from Cosmos sulphureus (yellow cosmos - YCL) and Delonix regia (royal poinciana - RPL) leaves were tested at concentrations of 0.015, 0.075, 0.15, and 0.3 g fresh weight/mL for 48 hours. Pre-soaked weedy rice (WR20) seeds were treated, and stem and root lengths were measured 7 days post-treatment. At 0.3 g fresh weight/mL, YCL extract completely inhibited WR20 growth, while RPL extract inhibited root and stem by 71% and 75%, respectively. WR20 seeds soaked for 96 hours before YCL treatment showed the highest inhibition. For RPL, 48-hour soaking yielded the highest root inhibition, and 96-hour soaking the highest stem inhibition. Evaluating effects on OM18 cultivated rice revealed YCL extract at 0.3 g fresh weight/mL inhibited roots (45.41%) and stems (1.72%) at 2 days post-treatment, with full recovery by 7 days. However, RPL extraction proportionally impacted OM18''s roots (33.35–100%) and stems (33.10–80.10%). These findings suggest that using YCL and RPL extracts for weedy rice management is promising, particularly when combined with strategic timing of rice planting to minimize damage.