We are again seeing nice weather in Denver, Colorado for growing pumpkins. Warm nights and not overly hot days are making the main vine run. My plant keeps growing 6-8 inches per day and we will be close for a July 14th pollination. You can pollinate your plants by hand or allow the bees and moths to do the work for you.
To pollinate by hand you take the male flower and peel back the pedals and then put the stamen around the inside of the female flower so the pollen is transferred. You can easily identify the female flower by the small bulb that looks like a mini pumpkin at the base of the flower. Many of the top growers will use the flowers from one plant to pollinate another plant so they can pick the genetic traits being passed to the next generation. If you don't plan on trying to develop genetic lines then you can just let the bees do all of the work for you.
Until about 10 days after pollination you will want to try to keep the pumpkin cool. Shade from a laundry basket over the pumpkin will help the plant from aborting the new pumpkin. Anything over 90 degrees can cause the pumpkin to abort so any kind of shade you can add can help give your pumpkin a good start.