What is the size of the granite pieces? Anything bigger than coarse sand will probably not hold enough water or nutrients to support a healthy lawn. I would remove it and replace it with the appropriate soil if the pieces are too big.

Get rid of the granite, regardless of the size of the pieces. Granite is not a planting medium. Best wishes--Carl

Actually decomposed granite is not a bad medium for several reasons, but in this case, it probably is not great. Decomposed granite tends to lock together forming a very stable surface. I'm thinking that locked together soil would be hard for roots to penetrate. Also the sharp edges of the granite would be a hazardous place for tender roots to grow. Granite makes a better topdressing or sand substitute than a growing medium - at least for grass.

I would set the granite aside and scatter it over the entire yard after you finish with this little section.

My granite was installed incorrectly. They did not put hardener in it so it is basically sand. When the sprinklers hit it it turns to mud. Do still need to remove it?

A picture of the granite would be helpful. The particle size of the granite in the bed, is necessary to give you a good answer.

Question. Is it a bed of granite or bed with granite mixed in with the soil. From you comment about turning to mud when wet, makes me think it is dirt mixed with granite, or a

"very" fine, ie sand, If so planting grass over it as you say would probably work.