Gravel beds

I like gardening but I don't know a lot about plant and just buy plants or shrubs that look nice. when I moved into my house 3 years ago I decided to have all my flower bed gravel and put a black weed cloth underneath. I am just wondering if this is hampering my plants growth. I have one section which is ornamental grasses but they are not growing like grasses should. Can anyone give me any advice on the effect gravel beds have.

thanks

angela