Cool Raised Garden Bed Bottom Cardboard Ideas. Easy way to prepare your garden bed. Cardboard cardboard is the ultimate mulching material for anywhere in the garden, including under a raised bed.

Then, it should have a layer of organic matter such as grass clippings, leaves, untreated wood chips, or straw for compost. Once it is filled, level the soil using a rake. Even the gardener’s helper enjoys a cardboard box!