Several studies have investigated the impact of high starch reserves, total carbohydrates, and C/N ratio on fruiting and fruit set in perennial fruit crops. This study aims to adjust the C/N ratio to address the fruit set failure of Barhee date palms. During the 2019 and 2020 seasons, Barhee date palms produced through tissue culture were subjected to treatments involving skipped irrigation and nitrogen (N) fertilization, along with a doubling of phosphorus (P) and potassium (K) fertilizers during the flowering and pollination stages. The results demonstrated a significant increase in fruit set percentage and yield when irrigation and N fertilization were skipped, and when P and K fertilization was doubled during these critical periods. Conversely, applying nitrogen fertilization and conducting irrigation during flowering and pollination adversely affected the C/N ratio, fruit set percentage, and yield. In conclusion, skipping irrigation and nitrogen fertilization, combined with doubling P and K fertilization during flowering and pollination, proved to be the most effective treatment for mitigating fruit set failure and enhancing the yield and fruit quality of Barhee date palms produced via tissue culture.