I've been growing pumpkins in home made growbags (old cat litter bags filled with well rotted horse manure).
Obviously I have to remember to put plenty of holes in the base of the bags.
One pumpkin has been yellowing badly over the last week. Today I checked the base of the bag and it's very wet and when I pierced the base a little dark liquid seeped out and there's quite a pong. So I'm figuring it's an insufficient drainage problem. Either there are insufficient holes or we (this was a project with my kids, and if you've ever gardened with kids you'll know it can get a bit chaotic) completely overlooked piercing the base of this one.
I've added fifty or so holes with a screwdriver. Is their a good chance the roots will recover and the pumpkin will revive? As I say, it's gone rather yellow, but it has barely wilted.
Edit, 1 month on:
Appreciate the suggestions on repotting and I am sure they are valid. However due to limited time in the garden, and a few days of OK sunshine I thought I would leave the plant to try carrying on in the same container (but with the newly punched drainage).
I figured that cucurbits at this time of year are pretty vigorous growers and it might very well make it without much further help.
So it has proved, with a pretty strong recovery. However it has a way to go if it is to catch up with the other pumpkins alongside it. And how well it will fruit remains to be seen.