+22 How To Build And Fill A Raised Garden Bed Ideas. Before you fill your bed, lay down a 1/4 inch to 1/2 inch of gravel underneath. Web deep raised garden beds are perfect for those who can’t garden at ground or low levels, but can be very costly to fill completely with quality potting mix.

Next step is to ensure your new garden bed is in the right. Place those measurements into an online soil volume calculator. Find one of these by searching on the internet.