In a large container, dissolve 1 1/2 cups sugar in enough water to cover the corn completely. Stir until sugar is fully dissolved.
Submerge corn ears in the sugar water solution and soak overnight in the refrigerator.
Remove corn from sugar water and pat dry.
Spread softened butter evenly over each ear of corn.
Season each ear with salt, pepper, and garlic herb seasoning to taste.
Wrap each ear individually in aluminum foil.
Preheat grill to medium heat.
Place foil-wrapped corn on grill and cook for 30 minutes, turning occasionally.
Remove corn from foil and place directly on grill grates.
Grill for an additional 5-10 minutes, turning frequently to achieve even charring.
Remove from grill and serve immediately.