How do you provide enough food for the pumpkin in a bucket. Presume you must have to constantly feed it?
Well yes and no!
First of all a pumpkin is predominately water hence the reason for me mentioning
'don't let them dry out'Then it is a case of how big do you want them!
Generally; If the compost in the container is a good potting mix this might you will get a fair sized pumpkin with minimal additional feed.
For instance I grow pumpkins for lanterns for my grandkids ( I grow Jack o' Lantern) and I find that I get a size suited to what the kids can lift.
eg like these;
If I want half a hundred weight plus, I grow the variety 'Hundredweight' and feed them a high Potash feed once or twice a week.
Some people give a half strength feed at each watering the choice is yours.
Then you will get them like this (or bigger)
This one was 42 lbs / 20 kg ;
I have also found that 'variety' plays a large part in the end result. In other words there is no point in feeding a plant/variety that doesn't have the potential to grow big in the first place.
The two varieties above are such varieties e.g Jack o' Lantern generally grows to around 12"-15" in diameter wheras hundredweight can be over 2ft in diameter.