Why is my bitter gourd not fruiting?

Bitter gourd produces male flowers first, then females appear 2–3 weeks later (look for a tiny gourd at the base of the flower). If only male flowers are present, wait. If both are open but no fruit sets, hand-pollinate by transferring pollen from male to female with a small brush. High nitrogen feeding delays female flower production — switch to phosphorus and potassium. Pruning the main vine tip after 10 nodes encourages more laterals and female flowers.