And it disturbs the weed seeds that have started to germinate, which makes them non-viable as well. The longer you continue this process the more weeds you are eliminating from your garden. Of course depending on the time of the year, there are a few billion weed seeds drifting through the air at any given time, so to think that you can eventually rid a garden of weed seed is false thinking, but at least this process is effective for the remaining roots, which are the most difficult to control. With that process complete, go ahead and plant your garden. When you're done planting you can either mulch the bed, or keep turning the soil on a weekly basis to keep it free of weeds.
Most people opt to mulch.
Not only does mulch help to control the weeds, but if you select a natural mulch it also adds organic matter to the soil which makes for better gardening results down the road. The newspaper will block the sunlight from reaching the surface of the soil and help to keep weed growth to a minimum. The newspaper will eventually decompose, and not permanently alter the make up of your garden. For one, neither one of them ever go away, and the make-up of your garden is forever altered until you physically remove them, which is a real pain in the butt. Plastic is no good for the soil because soil needs to breath.