To solve the Pumpkin Puzzle, you’ll first need to pick the rotten pumpkins and take them to the Regeneration Circle in the barn. There you can convert one into a seed that you can replant. Then you need to make all of the pumpkins light up at one time.
Video of this puzzle can be seen here: Pumpkin Puzzle on Youtube
Using the Regeneration Circle will convert the rotten pumpkin back into a seed you can then replant in the fields.
After you replant the seed, there will 3 waves of pumpkins where you need to click on them to light them up. The goal is to have all pumpkins lit at once.
In phase 1, in the left group, click the middle pumpkin. For the rest of the groups it doesn’t matter which one you click.
In phase 2, in the group on the left, click on the front left pumpkin. In the third group, click on the back left first, then the front right. For other 3 groupings, it doesn’t matter what order you click on them.
In phase 3, there are 3 main groupings of pumpkins. Follow the numbering in the picture to get the correct click order.
Completing this puzzle will get you the Pumpkin Light Bottle, which is used in the windmill.