The Best Raised Garden Bed Dimensions For Soil Ideas. ( unless the boards are very thick, don’t worry about inside/outside measurements.) convert all measurements to the same unit. For best results, there should be another 12″ or more of good soil below the bed.

11″ tall metal garden bed; Since you've questions, we've got. You could build a raised bed without a frame, and mound the soil 6 to 8 inches high, and flatten the top.