Tuli I always use newspaper under mulch on new gardens. Most of my gardens have been around for a while, I add mulch yearly so I put a thin coat of mulch after I aerate the soil. The aerating of the soil is the most important part of adding mulch. This distributes last years mulch into the soil where it can decompose,loosens up the soil so it can absorb water. A thick coat of mulch added on top of last years mulch will only cause problems down the road.
The first year I loosen the soil and add lots of bone meal. Then a few layers of newspaper, moisten it with water and add 2-3 inches of mulch. This get the garden off to a great start. The newspaper smothers out the weeds. The second year I loosen up the soil incorporting last years mulch into the soil. Add bone meal and re-mulch, this time only a inch or less.
After a few years of this practice the soil line becomes to high for the plants and will start to smother out your flowers as well as the weeds. This is when I need to remove some of the top soil when aerating, this soil is great for starting new beds. Once I've removed an inch or two I follow the same practice. Add bone meal and a new layer of mulch.
I know this sounds like a lot of work, but it pays off. Most of my gardens are weed-free. Except this year I have tons of oak and maple seedlings growing everywhere, it's not beause of the mulch, it because of all the rain. My garden work as doubled this year. I have never had this problem before and hope too never have it again.
