Packed dirt can be cultivated into a dirt tile using a [[rake]] or [[shovel]].
Packed dirt will eventually be overgrown by nearby [[grass]],[[tree]]s or [[steppe]] tiles, but not as fast as [[dirt]] would be so, in effect, packing the tile will slow the growth.
You are not able to pack dirt that is submerged in water, however it appears that packing dirt with one edge submerged is easier on South-East facing tiles, While NW facing tiles need to be completely raised from water to be packed.