The field experiment was carried out in bitter gourd cv. Paalee in Chitwan during the cropping season of March-May, 2019. 4 × 2 Factorial Randomized Complete Block Design (RCBD) was conducted with three replications. Four different mulching materials viz. silver plastic mulch, black plastic mulch, straw mulch and a control with no mulch were assigned as first factor whereas second factor consisted of two plant spacing of 1.5m and 1m (plant-to-plant).The analysis revealed that silver plastic mulch recorded highest vine length (468.71 cm), maximum number of nodes per main vine (44.47) and maximum number of branches per main vine (31.57).Days to first male and female flowering, and sex ratio were found significantly (p<0.05) lower in silver plastic mulch as compared to other mulches. Similarly, silver plastic much had highest average fruit length (26.9cm), average fruit diameter (6.95cm), fruit number per plant (16.23), individual fruit weight (285.14g) and fruit yield (61.5 tons ha-1), soil moisture percentage (47.45) and Benefitcost Ratio (BCR) (3.08).The control treatment with no mulch had the lowest of all these parameters. The plant spacing did not significantly (p<0.05) differ for all the characters, except average individual fruit weight, average fruit yield and BCR, which were found higher (265.07g, 50.91 tons/ha and 1.9 respectively in wider spacing. The interaction effects of plant spacing and mulching materials were observed only for average fruit length and average fruit diameter. This study suggests silver plastic mulch as an effective mulching material for better growth and yield of bitter gourd cv. Paalee.