This time of year you hear a lot from giant pumpkin growes about their pumpkin's main vines. Where you want to set (or pollinate) you pumpkin is on the main vine (or the origional vine that all of the side vines come out of). The minimum length that you want your pumpkin to set is at least 10 feet from the stump. This will give your pumpkin plant enough mass (i.e. leaves) behind the pumpkin to power the pumpkins growth.
The reason growers talk about the main vine growth this time of year is that it is important to get that main vine out to 10+ feet by about June 28th. At that time hopefully a little female flower will start forming and by 6 days later that flower will open up and be ready to be pollinated around the 4th of July. What is magic about the 4th for pollination? Pumpkin growing is all about timing. Growing a massive root system and getting enough leaves is important to power the pumpkin. The timing of when those events happen is equally as important. Growing salad to early in the season as a result of to much nitrogen can cause minimal root growth which will hurt you later in the season. Growing the plant too big too fast can also force you to remove hoop houses to early which opens the plants up to the elements and that can cause potential problems as well. However if you don't get your main out fast enough your pumpkin will start growing to late. Each day that your pumpkin isn't pollinated after the 4th of July will cause you 3-20 pounds of lost weight which can mean potentially a hundred pounds lost on the scale. Pumpkin growing is often about the little things. When you talk to heavy hitters you begin to realize there isn't a big secret or magic bullet to giant pumpkin growing. It is about doing the 30 small things right and those small things add up to big weights at the end of the season.
Right now I need to average about 5 inches a day in main vine growth in order to pollinate at 11-12 feet, which is my goal. I'll keep you updated on the growth. If I can do 3.5 inches per day right now and the weather gets warm I should be okay because the main vine should start growing a foot a day about 2 weeks from now.