Well planting in the ground isnt a bad idea idea but for a few reasons I prefer buckets. For one when you plant in the ground you want to make sure that the spot you pick will receive plentiful sunlight. I've chosen a spot that had sunlight and a few days later vegetation above it had grown and it was heavily shaded. At least in cups and buckets I can move it around if that ever happens.

Also its alot of animals where I live at so if I were to plant straight into the ground I would put wiring around the main stalk so they cant nibble it to the ground. To me buckets are more managable.. if you want to be discrete about it dig a hole and plant the bucket in the ground!