The productive potential of 11 guinea grass forage genotypes was evaluated at harvest intervals of 45 days during the short and long day seasons. Guinea grass genotypes PRPI 3637 and 3622 produced the highest dry matter yields. P. maximun PRPI 12917 (cultivar Makueny) was not different from 3637 or 3622 during short days; however, during long days it differed from cultivar 3637. In vitro true digestibility (IVTD) estimated by the predicting equation of Arroyo-Aguilú and Coward-Lord was similar for most cultivars under evaluation. Cultivar Guadalupe produced the highest IVTD values during both seasons. Among all genotypes, P. maximun 3637 and 3634 consistently had the highest average regrowth percentages and the best capacity to recover.