What should you put in the bottom of a planter box?

Put drainage holes and a layer of landscape fabric at the bottom of a planter box, then fill it with quality potting mix. Good drainage matters more than any material layered below the soil.

Water that cannot escape can rot roots, so the holes must stay open. Landscape fabric over the holes keeps soil from washing out while water drains. Some gardeners add a thin layer of coarse material like gravel or small stones, but this is optional. A deep layer can actually hold water higher in the box, so keep it shallow or skip it.

A simple setup:

• Drainage holes along the bottom or lower sides

• Landscape fabric laid over the holes

• Quality potting mix filling the rest of the box

Our how to build a planter box guide walks through drainage and layering, and our best materials for planter boxes article compares how different materials handle water. For Utah gardens, drainage also helps roots through hot summers and cold winters. See our custom planter box options for built-to-fit designs.