Grass does not grow on blocks of dirt that i place.

*What I expected to happen was grass would've grown on the blocks of dirt that i placed.
Grass should've grown over time.

*What actually happened was no grass ever grew no mater how long I waited, i played for hours and the grass still did not grow.
I was build ing a pen for my sheep to live in and i was placing dirt down in the pen and the grass did not grow. So the sheep could not eat grass and get wool to grow back.

Steps to Reproduce:
1. Place dirt on the ground in survival.
2. Wait for grass to grow.
3. Grass does not grow