All you need is a couple seeds, which in the case of giant pumpkins, are REALLY BIG! I planted Atlantic Giant seeds. There are a couple varieties of Giant Pumpkin seeds; I think Big Max is another one.
I planted them in a patch right behind my house. The only requirements for the patch is that it be very sunny and easy to water. I planted four giant pumpkins, which was fun, but even two would be fine! I would not advise planting only one, because then all your hopes and dreams are pinned on one plant, and if something happens to it, you will be so sad.
When I took this picture, I thought these leaves were incredibly huge.
I had no idea of the amazing, amazonian leaves that we yet to come!
This is why I call it one-seed landscaping: just by planting a couple seeds, I created a huge gorgeous garden feature!
They grow so fast that there is always something new to see. One thing you can do is keep your eye out for female flowers, because they are the ones that might become pumpkins. You can easily tell the female flowers even before they open up, because they will have a big round swollen part right under the flower. There will be many more male flowers than females, so it is exciting to spot a female flower. If you have only a few pumpkin plants or not very many pollinators (bees) in your yard, you actually might want to help your female flowers get pollinated. The easiest way to do this is to just pick a male flower, and swirl the pollen-y stamen all over the female flower's pistil. I know, I know. Anyway, if the female flower does not get fertilized, the little swollen part will just shrivel up, which is also interesting to see.
If it DOES get fertilized, it will start growing like gangbusters, and you'll be so proud.
That's right, they are acting like umbrellas, because they are really hoping it will rain. If they do this, turn on the sprinkler, for heaven's sake.
There are other things that might happen to your pumpkins. Powdery mildew is the most likely, and if you figure out how to cure it, please let me know. Another possibility is this atrocity, which I call, suddenly-decided-to-rot-like-crazy. Pretty sure this one is terminal.
Pumpkins are not forever.
I said this once already, but I think it bears repeating: you need a compost pile. Maybe that will be another good blog topic for me...
In conclusion: you have a yard; plant something in it! It's not that hard, and it's awfully fun!