Squash and pumpkins have male and female flowers. The male flower consists of the flower with a single stamen and a stem. The female flower consists of a flower with multiple pistils in the center and behind the flower is a baby squash before the stem. The pollen is produced in the male flower and that has to get into the female flower. Bees usually do this, but sometimes it's good to pollinate by hand. This can be done by tearing the petals off of a male flower, leaving just the stem and stamen, and inserting the stamen into the female flowers pistils enough that pollen (yellow dust) gets left behind. Once the female flower is pollinated, the baby squash will dramatically increase in size - like double over night. If pollination fails to occur, the baby squash will whither, yellow and fall off.

Male flowers ususally appear first on a plant. Then after a few weeks, when the plant is large enough to support fruit, females will begin to appear. All of the flowers open for only a little while in the early morning and only for a day or two. After that, they die and fall off of the plant.

So look for those female flowers, hand pollinate in the morning and boom, pumpkins!

Hope this helps!
Susan