While you can pick and eat pumpkins as soon as they are large enough, if you want to store them, you need to let the vine die off completely. This allows the fruits to harden, and when you do pick them make sure leave at least 10cm of stalk attached to the fruit.
Another tip is to never pick the fruit up by this stalk, no matter how tempting it is, as if it snaps off it provides an entry point for decay and the pumpkin will go rotten.
Only store pumpkins that aren’t damaged or injured, and store in a cool, dark place.
Ensure the pumpkins are not touching each other when stored, and check them weekly to make sure nothing has gone rotten.
Thick skinned varieties of pumpkin can be stored for around 12 months (sometimes longer) whereas the thinner-skinned varieties must be consumed earlier than that.