Reverse psychology.

Frederick II of Prussia wanted people to grow potatoes which were more nutritious than the grains they were used to. Yet there was a risk of revolution if he tried to force such a major change in people's diets. So, he came up with a plan. He had gardens planted with potatoes only for upper classes & soldiers, telling commoners they couldn't have this luxury. They were heavily guarded - during the day, that is. At night, after the guards went to bed, peasants snuck in & took the forbidden food to plant in their own plots.