This experiment was carried out in one of the fields (A) affiliated to the College of Agricultural Engineering Sciences / University of Baghdad, for the spring season 2021, On hybrid tomato plants (Mayai Mayai) to test flower viability, using two factors, the first was three levels of irrigation interval (2, 4, 6) days, and the second factor three concentrations of compound Nano fertilizer with concentrations (0, 1.5, 2.5) gm liter-1, so that the number of treatments is 9 treatments and three replications, the number of experimental units is 27 experimental units distributed randomly according to the random drawing method to ensure reducing experimental error and obtaining the most accurate results. A factorial experiment 3 x 3 x 3 was carried out according to the Nested Design with Factorial design (RCBD), and the results were analyzed using the statistical program Genstat version 12, the means were compared according to the LSD test at the level of significance of 0.05. The results showed a significant superiority of treatment S1 with irrigation interval of 2 days with treatment of N2 with a concentration of 1.5 gm l-1of Nano fertilizer in most of the flowering characteristics of tomato plant in both the number of leaves before the first flowering cluster, the number of days from planting the seedlings until the first flower opens. Plant-1, number of flowers in the flower cluster. Plant-1, number of flowering inflorescences. Plant-1, the number of days from planting seedlings until holding the first flower. Plant-1, the percentage of the contract %, the results were (4.67, 22.33, 6.33, 24.0, 27.33, 81.54) respectively compared to the 6- day irrigation interval treatment, which gave the lowest values (10.00, 31.00, 3.67, 10.67, 38.00, 55.37), respectively