In 2017, guava plantlets were planted at different densities to study their growth, flowering, and fruiting behaviour under ultra high density system of orcharding. The experiment was laid out at the Horticultural Research Station, Assam Agricultural University, India, in Factorial Randomised Block Design. The plants accommodated at lower density exhibited improved growth, all the plant growth attributes except the plant height tended to increase noticeably with the decrease in plant density from 10000 to 4444 plants ha-1. The canopy spread in east–west direction was larger in the population density of 5000 plants ha-1 while the north–south canopy spread was greater among plants with density of 4444 plants ha-1. The significantly higher number of flowers, fruits per branch, highest fruit set and lowest fruit drop was recorded in widely spaced population during both winter and rainy seasons of the investigation. Although the rainy season crop bears more flowers and fruits, the fruit setting was higher in the winter season during both years of experimentation. The nutrient level also significantly influenced plant vegetative and reproductive growth, an increased trend was observed with increasing nutrient level, and among all, the highest level of nutrient (70:45:35 g NPK plant-1 for first year and 130:75:65 g NPK plant-1 for second year) exhibited considerable superiority.