To grow bitter melon plants, select a warm and sunny area with organically rich, sandy or loamy soil that drains well. Soak bitter melon seeds overnight in water to speed up germination. Sow the seeds directly in the planting area in late spring or early summer. Install a trellis or other support structure for the bitter melon vines to climb.
Prepare the soil in advance by loosening the soil in an area about 2 feet in diameter and 1 ½ feet deep. Mix compost or dried manure before planting. Make holes about a half-inch deep and spaced 12 inches apart in the soil. Put two seeds in each hole, cover well with soil, and water well. Surround the holes with manure and mulch to prevent weeds and conserve soil moisture.
Allow the soil to dry out slightly between watering to prevent rot. Install a stake or a trellis about 8 feet high to support the bitter melon vines. The seeds germinate in eight to 10 days and develop lateral shoots within four weeks of sprouting. Cut off the growing tips of the branches when they are 3 feet long, as this produces side branches that yield more flowers and fruit. Use fungicides if vines have fungal problems, and in case of fruit flies, wrap each fruit in a paper bag.