Right now I'm playing survival island map and I'm slowly covering the island with dirt. But for some reason no grass seems to be growing on the dirt blocks even though they are out in the sunlight. Can someone tell me how to fix this?
I mean the grass that grows on dirt blocks. Not tall grass.
Before we can really help you, you need to clarify whether your talking about tall grass or grass blocks. Tall grass doesn't grow naturally you have to use bonemeal on a grass block, and grass blocks don't grow they spread from other grass blocks.
If you're on a survival island and there is no grass left, you're out of luck. Grass can only spread from other grass blocks, therefore:
Grass Block + Dirt Block = 2 Grass Blocks
Dirt Block + Dirt Block = 2 Dirt Blocks (to infinity, I suppose)