Luffa gourd planners are very fast growing plants (vines may reach up to 15 feet in length). The falling of flowers may happens for two reasons;

1. Pollination: Even-though luffa gourd produces large number of male and female flowers (generally 10:1 ratio), it mainly depends on bees for pollination. In general if the pollination does not occur, female flower will fall off or it may grow initially but fall off later. So if your garden is lack of bees you should go for hand pollination by using brush or cotton swab to move pollen or pull off a male flower and gently rub the yellow hair-like structures of the male flower against the middle parts of a female flower. Repeat the procedure for 2 to 3 days.

(Both flowers look similar but male flower grows on long peduncle and first to appear. It bloom for one day and then fall off. Whereas female flower grows on short peduncle but it has an ovary in the shape of the fruit).

2. Another possible reason may be due to lack of female or male flowers. Generally luffa gourd produce single female flower on one stalk and clusters of male flowers in sequence in another stalk. So if plants produces only male or female flowers there will be no pollination. Also some plants may not produce enough males or females. It mainly happens due to nutrient elements in soil. If the soil contains high nitrogen, the plant will produce more male flowers whereas high phosphorous increases female flowers. So if you have less female flowers apply phosphorus to soil.