Well, a couple things.. first patience and acceptance are traits you will learn as a gardener. You WILL lose plants in the course of learning. It's a matter of how many and when.

Now, to the actual problem. Can you post pics of the plants? That would help. Pumpkin plants do drink a LOT of water so it may actually be an under-watering problem.

Pumpkins do best direct seeded. You should still have plenty of time.

Here's a few samples. I know not to expect to bat 100, but two years in a row of failure, then to finally have them thrive only for this to happen... Grr.
I just thought it was odd that it happened within 16 hrs of watering and it wasn't overkill.

Here is a link that might be useful: Pumpkin pics

Well to be honest they still look quite healthy. They just look wilted. Given the size of the pot and the size of the plant, they could definitely be running out of water. I container grow pumpkins all year and over-watering is the one thing I never had a problem with. Pumpkins have large root systems.

Are you planning to move them outside? I would definitely get them into bigger pots or outside soon depending on the temperatures.

Thanks for the reply. Those pics were taken just a few hours after I noticed the issue. That wilted section turned dry brown and basically fell off at the touch. My main concern was that the same thing started happening to other random leaves on other plants and I wanted to nip it in the bud. I gave them some more water after 2 days without advice and the dirt drying considerably. At this point there has been no steep decline or healing, just staying about the same and seeming stunted. I posted the message because I have no idea if I've over/under watered them or over/under fed, too much/little light etc... I've been holding off on bringing them outside as although we haven't had frost in a while, we've had unseasonably cool, cloudy, wet weather and I don't think they will thrive in that environment. Does anyone have a minimum nighttime temperature at which they won't suffer.?

To me, (although I am certainly not an expert), this kind of appearance is typical of over-fertilizing. Using one every few weeks isn't too often but make sure you're not dousing the plant with it, a little goes a long way since you ALREADY have manure in there. That's fertilizer enough. They'll survive, just keep watering them with plain water for awhile to let them recover.

My pumpkin plants have been at temps of maybe 58 at the lowest at night and they're fine. Good luck!

Nick, out of curiosity which zone/area are you located in? We've been having very unseasonably cool weather in the northwest so I can understand the reluctance to put them outside. Our highs are barely starting to reach the lower 60s and my typical lows are still mid to upper 40s. I'm guessing at least 2-3 more weeks (probably the end of the month) before mine go outside.

Vancouver, bc, Canada. So I guess we are in the same boat.

AHA! A partial epiphany and a bigger conundrum. Most of the plants are in 10" pots, but the worst one was in a 8" pot it was fading fast. I went to transplant it in a bigger pot yesterday to find the bottom was VERY dense with roots. Now that was a standard conneticut field, but the remaining ones are Atlantic giants!!! My problem is that due to unseasonably cool wet weather (7c-17c) they aren't ready to go out. For the bin laden justice squad among you, roughly 45f-65f :). I know that best solution is to transplant to bigger pots, but we barely have room as it is and I don't know if they can handle being transplanted twice in a few weeks. Any ideas?

Get some 2x2 lumber, heavy clear plastic sheeting, some drop lights, and look up "How to Grow World Class Giant Pumpkins". They will show you how to build a mini greenhouse for your vines so you can plant them out early and get them into some rich soil with room for their roots to spread. Be prepared though... Atlantic Giants grow about a foot per day and can use upwards of 2000 square feet of growing space PER PLANT! It sounds to me like they are wanting to run but can't. Hope this helps.