The purpose of this study was to assess the effects of compost percentages (0, 5, 10, and 20%, w/w) and mineral fertilization treatments (5.5, 11, and 16.5 g NPK/pot, 25 cm diameter) as well as their interactions on the flowering and some chemical compositions of Antirrhinum majus, L. during the two consecutive growing seasons of 2022/2023 and 2023/2024 at the Floriculture Farm, Faculty of Agriculture, Minia University. All used of compost percentages significantly increased flowering traits (inflorescences stalk length, number of inflorescence stalks, number of florets per inflorescence, fresh and dry weights of total florets per plant, and flowering duration), seed yield, photosynthetic pigments and NPK% relative to untreated plants. In all cases, 20% compost was significantly superior to other used treatments. Mineral fertilization considerably increased all abovementioned traits facing the check treatment. The treatment of 16.5 g/pot,
followed by 11 g/pot produced the highest values without significant differences between them. The most effective interaction treatment was giving snapdragon plants with 20% compost together with 16.5 or 11 g mineral
NPK/pot.