I'm hopin' longy can answer the moldy part too...
I am not sure one way or the other...
But a way to solve the problem I found when using
grass as a mulch was to take one of those flats
I got my
flowers in and kind of "sift" the grass on to the top of the dirt, and it gave it an more
even coating, and not too many lumps and piles...
and spread it out better for me.....
For me, the grass ended up getting like a dry piece of something over the top of the soil
and didn't allow enough moisture in, and would even act as a barrier to the water and it would roll off the top and down where I didn't want the water..
I used grass, as well as a ton of other ideas...
I ended up using landscape fabrics on my raised beds, and haven't gone back to any other method since..I re~use the fabric every year... it stays
right on top of my dirt, only removing it to add/admend soil, and re~configure planting scheme.
Then back on, re~
plant and it's good to go...