The guava (Psidium guajava L., Myrtaceae) is originates of Tropical America and is distributed throughout the Brazilian territory. The seedling production stage is very important because seedlings of higher quality have a direct influence on success and final production. Therefore, it is necessary to use substrates with good nutritional quality to supply the nutrient demand of the crop. In this way, the objective of this study was to evaluate the germination of 'Cortibel' guava seeds and initial development of the plants in different substrates. The seeds were obtained in physiologically mature fruits and sown in 1.5 L bags with two types of substrate (sand and commercial substrate Bioplant ®). The design was completely randomized, two substrates were the treatments with nine replicates and each repetition with five bags, totaling 45 experimental units for each treatment. Germination was monitored for 129 days. The characteristics of plant height, stem diameter and number of leaves were evaluated. The substrate sand provided a higher germination rate in relation to the Bioplant ® substrate, however, the use of commercial substratum presented a higher initial development, with higher values of plant height and stem diameter, which is indicated for the production of seedlings of guava 'Cortibel' by seeds due to the presence of nutrients in its composition.