When Do Pumpkin Plants Flower?

Pumpkins produce both male and female flowers.

Pumpkins are harvested, eaten and used for decoration when temperatures are cool in much of the country, but a pumpkin is considered a warm-season vegetable. Pumpkin seeds do not germinate in cold soil and their seedlings are injured by frost.

Bloom Time

Pumpkin vines begin to flower in the middle of summer.

Pumpkins bloom in mid- to late-summer, according to Cornell University Home Gardening. Pumpkins produce large, yellow flowers, ranging from 4 to 5 inches in diameter, and they have coarse, medium-green foliage.

Male Flowers

Pumpkins, like cucumbers, gourds, squash and watermelon, are cucurbits, which means the first flowers to appear on their vines are usually male and do not bear fruit. The male flowers produce pollen, which bees then carry to the female plants. When the first female blossoms open, the bees, already familiar with the route, distribute the pollen to them. Male flowers usually bloom for one day, then drop off of plants.

Bees

Bees required for pollination may be killed by insecticides. Apply insecticides in late afternoon or early evening only, when blossoms are closed and bees are no longer visiting.

Harvesting

Water plants deeply, but not frequently, until they bloom and set fruit in mid- to late-summer, then water regularly. Harvest pumpkins when they are a deep, solid color and rinds are tough.

References

• University of Illinois Extension: Pumpkins and More
• Cornell University Home Gardening: Pumpkins
• Purdue University Agriculture Horticulture and Landscape Architecture: Pumpkin - Flower
• Colorado State University Cooperative Extension: Spring Is the Time to Plant Pumpkins

Resources

• Oregon State University: How to Grow a Monster Pumpkin
• University of Delaware: Crop Pollination by Bees--Squash, Pumpkin, and Gourd
• The University of Arizona Cooperative Extension: A Collection of Pumpkin Recipies