This really works - we did it for our raised beds and regular garden, no weeds for two years!! The newspaper will prevent any grass and weed seeds from germinating, but unlike fabric, it will decompose after about 18 months. By that time, any grass and weed seeds that were present in the soil on planting will be dead. It’s green, it’s cheaper than fabric, and when you decide to remove or redesign the bed later on, you will not have the headache you would with fabric.
When I was in the Master Gardener program we used the water crystals in planters and I knew it was the same thing in diapers, but it never crossed my mind to put a diaper in the bottom of one. Someone else said, "The trick to amazing potted plants - diapers. I did this in my hanging baskets last year and they rocked all season."