Optimizing spawn quality is crucial for successful mushroom cultivation, and it relies on grain formation. This study was carried out at Faculty of Agriculture, Zagazig University, Egypt during the consecutive seasons of 2021-2022. In this study, a hatchery was developed using various grains. The grain substrates, including maize, sorghum, wheat, and a mixture of maize: sorghum: wheat spawn (1:1:1), were inoculated with Pleurotusflorida parent eggs. After incubation, the eggs were grown in rice straw substrate, exhibiting variable effects on the days from sowing to the first flushing (15-33 days).Notably, sorghum grain substrate demonstrated the highest productivity in yield quantity and fruit size, followed by the wheat-sorghum mixture in both seasons. The nutritional richness of sorghum and the 1:1:1 mixture played a pivotal role in stimulating robust fungal growth, influencing both yield quantity and morphological characteristics of the fruits. Considering these results and previous studies, the utilization of sorghum grain substrate is strongly recommended.Moreover, introducing Slim as a hatchery carrier can enhance hatching quality, fostering faster and       healthier growth. This approach aims to maximize returns, ultimately leading to increased profits in mushroom cultivation.