Cultivation, Propagation, and Planting
Propagation is through direct seeding and transplanting.
Mainly a warm season plant, bitter gourd thrives in hot and humid climates. The best medium for the seeds is a fertile, well-drained soil with a pH ranging from 5.5 to 6.7, enriched with organic matter, such as compost or dried manure. But it will tolerate any soil that provide a good drainage system (sandy loam soil, but it will grow I areas with poorer soils.) It should be in a frost-free area and will prefer the climate with daytime temperatures between 75 and 80F. The soil must be prepared well by adding organic matter before planting. Seeds soaked in water will germinate sooner. Soil temperature for germination is at least 60 to 65F.
Since this is a very fast growing vine, producing many fruits that will rot on moist soil, trellising will reduce diseases and make harvesting easier. When the vine reaches the top of its trellis, it is recommended that all lateral branches from the soil up to the 10th node as well as the growing tip of the vine be cut off as this will stimulate the upper branches and produce a higher yield.
While vines are blooming over a six month period, Bitter Melon needs insects such as honeybees to carry out the pollinating process for setting fruits. If the insects are not available in your area, the pollinating process can be done manually, by picking up male flowers and transferring pollens (face-to-face touching the center part of flowers) to female flowers. Female flowers have a fat section between the flower and vine stem. This process should be carried out when flowering is active during the daytime. If the pollination is a success, the fat portion will grow into full size fruit.
Regular watering with plenty of water is essential for its growth. Flowers will start appearing in 5-6 weeks and fruition will occur between two to four months. Mature fruits are ready to be picked within 3 months from planting and they will be light green and juicy with white flesh but bitter.
Pick the fruits every 2-3 days when they are still at the tender stage. Regular picking is important as fruits will become more bitter as they mature and it can also hamper the growth of new fruits.
Vines should be pruned at the tips when female flowers start developing to encourage branching and fast bearing. Regular fertilizing is essential for its growth. Water immediately after applying fertilizers.
The developing fruits must be watched closely or they grow too large and become bitter. Eight to ten days after blossoms drop, when the fruits are 4”- 6” long, light green in color and pear shaped, the gourds should be harvested.
Some vines should be left in the field to produce gourds for seed. Seeds continue to mature inside the gourd even after harvest. Seed that is sorted, washed and stored in a cool, dry spot, will remain viable for 2-3 years.
Leave some fruits to reach full maturity if they have to be reserved for subsequent crops. When fully mature, the fruits will break open on their own and release brown or white seeds which can be collected.
Diseases and Pests
Like other cucurbits, Bitter Melon vines are susceptible to several insect pests and diseases like downy/powdery mildew, mosaic virus (watermelon mosaic virus), wilt, fungi and pests like root-know nematode, which can be controlled by sulfur dust. Rust disease is controlled by spraying foliage with oxycarboxin. It is best to plant resistant varieties, mulch to prevent weed competition and use pesticides that are not toxic to honeybees.
The fruits are subject to attack by various fruit flies and fruit rots. Pests attack on fruits can be prevented by wrapping fruits with newspapers, when they are about a few centimetres long.
Some sources advise to grow Bitter Melon just like you would grow cantaloupe and honeydew melons.
Prepared by the National Bitter Melon Council