Fill 6-inch-deep plastic pots with a growing mixture comprised of 2 parts potting soil, 2 parts medium-grit sand and 1 part perlite or vermiculite. Leave a 1/2-inch gap between the top of the pot and the surface of the growing medium.
Sow two bottle gourd seeds in each pot. Press them into the soil to a depth of 1.5 inches. Make sure they are completely covered so no light can reach them.
Pour 2 cups of water into each pot so the soil is thoroughly moistened at a depth of 3 inches. Maintain moisture at a 3-inch depth during germination.
Set the pots on a sunny window ledge where temperatures stay around 78 F during the day. Apply bottom heat with a propagation mat if temperatures are too cool.
Watch for germination in four to eight days. Thin the bottle gourd seedlings to one per pot as soon as they produce a pair of mature leaves.
Keep the bottle gourd seedlings indoors under warm, bright conditions until one week after the last frost, then plant them 9 feet apart in a sunny bed with good drainage.