Hi, there is no inlay to the planter. Some of our clients have used the following method to fill in the planter:

1. Rocks, Styrofoam peanuts, and or Styrofoam boxes
2. Once the base is filled (see point #1) to a flat desired level, place a piece of landscape fabric cut to size of the interior of the planter and lay over the top of the filler material. This is to keep the soil in place and not fall through the cracks.
3. Fill in with soil / planting mix

We hope this helps.