Trying to figure out if I can make flower beds for crops on the roof of a building by moving dirt, OR can I plow ground so that all the grass goes away making it easier to see planted crops?

These items like dirt as it tells you when placing crops/water etc, but I don't think you can move dirt around, I'm loving the idea though coz I've made a base on top of the red rocket garage rooftop, looks quite cool, but no dirt up there for obvious reasons.