Why Didn't My Pumpkin Set Fruit?

Does your pumpkin completely lack fruits, rather than having small, stunted ones?

If the vines have been completely devoid of fruit, the culprit is likely due to a lack of pollination. Did you notice a drop in the bee population recently?

Is it still early in the season?

Was the weather overly hot and humid early in the season?

Are your pumpkins overcrowded?

Was there a dry spell before flowering?

Pumpkins rely on bees for pollination. If there aren’t many bees visiting your garden this could be the issue with pumpkins not setting fruit. You can attract bees to your garden by growing colorful plants and providing valuable food for them. Also, by installing habitats such as a bug hotel you can create a home for bees, making them a permanent guest who will reliably pollinate your various plants throughout the summer.

Pumpkins produce both male and female flowers. Male flowers appear first, so if you see the pumpkin vine flowering but no fruit and it’s early in the season, don’t panic. It just may be a matter of waiting for the female flowers. Female flowers appear further down the vine and may not show for up to two weeks after the appearance of the males.

If the weather is overly hot and humid early in the season, some plants delay the production of female flowers. If the pumpkin delays female blossoming, late sets often do not have time to develop before the days shorten and colder weather sets in.

The problem might be overfeeding with a fertilizer rich in nitrogen. Too much nitrogen in the soil can prevent female flower production, meaning you are left with all-male flowers which are unable to pollinate one another. Signs of nitrogen toxicity in pumpkin plants include yellowing of leaves and “burnt” edges, causing them to crisp and go brown.

Planting too close together increases shade, which will affect how and when the pumpkin flowers. The close competition also makes it difficult for bees to get to the blossoms. The shaded areas may also be under pollinated because it is cooler.

Pumpkins are heavily reliant on large quantities of water to remain healthy, making them difficult to grow in containers that can only hold limited water. Mulch the soil around the base of your plant after rain or watering, using well-rotted compost or manure. This will help keep the roots cool and retain moisture.

Flooded soil can damage root systems, causing wilting and a flower or fruit abortion. If you have been watering excessively or if your pumpkins are growing in compacted soil the problem may be overwatering.