Roots show geotropism because they grow toward gravitational pull.

Roots show positive geotropism because they grow down, in the direction of the gravitational pull. Geotropism, also known as Gravitropism, is a coordinated process of differential growth by a plant or fungus in response to gravity. For example, stems grow up and away from the gravitational pull so they show negative geotropism.

Breacking the law and lazy

You should never redesign your experiment. try and see what in your experiment you made a mistake on or try and test your experimemt with somebody else. see if they get the right results.