In agricultural production, the phenomenon of flowering without fruiting is fairly common. Basically all cucurbits need artificial supplementary pollination to set fruit. This should already be common knowledge, and no one should make a mistake on that point. So apart from that, the accurate way to describe flowering without fruiting is this: only male flowers open while female flowers are lacking, and even when a few female flowers do appear, fertilization and fruit set still fail to occur! This is the phenomenon seen most often in production.

Actually, to get to the bottom of this problem, let us first analyse the internal causes.

First, a lack of female flowers. For crops like pumpkins, watermelons and winter melons, the hot summer weather is not a particularly suitable season for their growth, so even when flowers appear they are male flowers, with few female flowers. Solving this problem is not difficult either; you just need to promote female flower development! In production, auxins or auxin analogues are commonly used to treat the flower buds, which can promote the differentiation of flower buds into female flowers. This raises the chances of pumpkin fruit set!

However, a lack of female flowers is not solely a weather-related issue. If the plant's nutrient supply is insufficient, it is likewise hard to achieve the goal of more female flowers. Therefore, strengthening the nutrient supply during the flowering period is also a major point in management.

The next case is when female flowers do open and hand pollination is carried out, yet fruit still fails to set! This is largely related to the current weather. Right now we are basically in the hottest weather of summer, and the vitality of pumpkin pollen is strongest at ten in the morning, but by then the temperature has generally already reached a high of 30°C. At such temperatures, even after pollinating flower to flower, the chance of successful fertilization is very low.

Here is a little tip for you: in agricultural production, you often see farmers in summer treating tomato flowers to set fruit! This is because seedless tomatoes happen to make use of the way auxin stimulates ovary development to achieve ovary expansion, and pumpkins can actually do the same, though because pumpkins are larger in size, the auxin dosage also needs to be considered carefully.

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