When using a planter with drainage holes, it's a good idea to place a layer of small rocks or pebbles at the bottom. This acts as a drainage layer, allowing excess water to flow freely through the soil and out of the drainage holes. It helps prevent the soil from becoming waterlogged and promotes better drainage. Additionally, you can use a piece of mesh or a coffee filter to cover the drainage holes before adding soil. This prevents the soil from escaping while still allowing water to drain.