That's fine. Water will get through and won't evaporate quickly. It's just that the nuggets do swell some and if next to the crown of a plant will keep it too moist. You can go up to 2" but more than that will not give you extra benefit. I know it sounds counter-intuitive, but think about how nature works. She puts down a little bit at a time. By the time the next season's leaf drop comes around, what was put there the previous season has already decomposed a lot, so the next thin layer doesn't block moisture from getting through. Nature is a great teacher.
Mulching is really a great tool, but you have to make it work with your plants. You can move "pretty" away from the crown of the plants. Their roots spread out from the crown so they will still be protected.
Smiles,
Lyn
