Seagrass meadows are an important habitat for iconic megaherbivores like dugongs and turtles and their foraging patterns found to effect on seagrass flowering. An aquaria experiment was designed to test the impacts of simulated megaherbivore grazing on the timing (i.e., number of days to first and peak flowering), abundance (i.e., the density of spathes and the percentage of flowering shoots) and morphology (i.e., height and the number of spathes per shoot) of the flowering of Zostera muelleri. Prior each flowering seasons (~20-24 weeks), seagrass samples were cropped to 1 cm and 3 cm lengths to represent dugong and turtle grazing respectively (n = 5) and flowering measurements were taken weekly over two consecutive flowering seasons. Timing and morphology of flowering was not significantly influenced by cropping. However, cropping had a significant effect on the density of flowering due to the low resource investment on sexual reproduction. A significant reduction in the percentage of flowering shoots was only observed in the 1 cm group, indicating that the plant invests more resources on vegetative growth when all aboveground biomass was removed. Reduced flowering densities need to consider in seed-based restoration in grazed areas and designing seed nurseries.