Hi hog devotee
If there are hogs still visiting then it’s best to keep leaving some food out. If the hogs stop visiting, it’s up to choice a bit. I would leave food out for about a week after hogs have stopped visiting and gradually reduce amounts. Then you might like to continue to put out a small amount of food, in case a hog turns up, or just keep a look out. I always keep my cameras going all winter in case any hogs turn up.
Some people worry about them not finding food immediately, but hogs do tend to come out for short periods during hibernation and it seems likely that these periods of activity are built in to the amount of fat they put down for hibernation. The problem may arise if they stay out too long, but hopefully, by that time you will have seen that they are out and about and offer food again.
The really important thing is to leave water available for them. It sounds a bit strange saying that when in some areas there is too much water around, but there will inevitably be areas where water is hard to find. So I would leave water available all day every day, including winter. You might try to leave some in a sheltered place where it’s less likely to freeze, or if you are really dedicated put some more out late at night to give any hogs which are around more chance to find unfrozen water.