What Soil for Bitter Melons?

Warm Temperatures

• Bitter melons require a constant soil temperature of at least 75 degrees Fahrenheit for healthy growth. Soil temperature needs are higher for germination, requiring a constant soil temperature of 85 degrees Fahrenheit before the seeds sprout. These preferred soil temperatures are only available within the U.S. Department of Agriculture's hardiness Zones 9 through 11. Gardeners living outside of hardiness Zones 9 through 11 must grow indoors in containers filled with loose potting soil.

Acid Soil

• Acid soil is ideal for bitter melon vines. Soil pH (potential hydrogen) ranges from 0.0 to 14.0. Neutral soil falls within the 7.0 range. Anything under 7.0 is acidic, above 7.0 is alkaline. Optimum soil pH for bitter melon is 6.0 to 6.7, but the vines can tolerate a pH as high as 8.0. A soil pH testing kit, sold in garden centers and by online retailers, can determine the soil pH for gardeners unsure of the soil pH in their region of the U.S.

Modification

• Soil modification is necessary before planting if the pH is not within the bitter melon vine's preferred range. Tilling the soil to a 12-inch depth will break up large chunks of earth, creating a finer soil for planting. A modifier such as lime or peat moss mixed in with the broken soil will adjust the pH. Add lime to soil below 6.0 to raise the pH. Add sphagnum moss if the pH is above 6.7 to lower it. Instructions listed on the modifier's manufacturing label contain application amounts.

Planting Specifics

• Bitter melon planting takes place any time of year in the warm climates of hardiness Zones 9 through 11. Seed planting depth is no more than 1 inch in moist, not saturated, soil with a 15- to 18-inch spacing in between seeds. Transplants are ready for planting in broken soil when they reach 4 inches high. Stakes or trellises hammered in behind each plant offer support when fruiting begins. Soil should be moist at all times throughout the growing season.