Garlic farmers often seek strategies to improve yield and post-harvest storage longevity. This study investigated the impact of various supplemental potassium fertilizers on these parameters. The experiment, conducted in 2021 and 2022, utilized a randomized complete block design with seven treatments: two levels of potassium nitrate (2.5 and 5 g/L), two levels of potassium citrate (2.5 and 5 mL/L), two levels of potassium silicate (2.5 and 5 mL/L), and a control without fertilizer. The findings revealed a clear influence of supplemental potassium fertilization on several key aspects of garlic growth and quality. Applying potassium nitrate at 5 g/L consistently outperformed other treatments. Plants receiving this treatment grew taller (72.93 and 90.80 cm), boasted more leaves (9.20 and 12.03), and showcased the largest bulb diameter (5.40 and 5.21 cm) and highest number of cloves per bulb (14.60 and 14.30), ultimately translating to the highest total yield per feddan (feddan = 4200 m² = 0.420 hectares = 1.037 acres) (12.61 and 12.75 ton) in both seasons, respectively. Notably, this treatment also led to significantly higher chlorophyll content (78.67 and 73.45 SPAD unit) across both seasons, respectively, suggesting enhanced photosynthetic activity and improved plant health. Beyond these morphological features and yield benefits, the study explored the impact of supplemental potassium fertilizers on post-harvest storage quality – a crucial element for farmers aiming to minimize losses. The results were encouraging, indicating that supplemental potassium fertilization contributes to reduced post-harvest loss compared to the control. While all potassium treatments displayed positive effects, potassium silicate and potassium nitrate at 2.5 g/L offered the most significant reductions in percentage weight loss during both storage periods (one and two months after harvest). These findings highlight the importance of potassium management for optimizing garlic production and post-harvest handling, providing valuable insights for farmers and agricultural stakeholders seeking to maximize their yields and minimize losses.