To ensure that plants receive the proper amount of food and water, you'll need to layer the pot with a combination of soil and additives. Start by placing pottery shards over the container's drainage holes, then add 2 to 3 inches of gravel. (If weight is a concern, use styrofoam "peanuts" instead.) This bottom layer allows water to drain away from roots so they won't rot.
Next, mix 4 parts potting soil to 1 part sand or perlite, which enhances the soil's drainage. Add in a slow-release fertilizer according to package directions. Then fill the container to within 2 inches of the top with this mixture. In extremely hot, dry areas, augment the bottom third of the mixture with a wetting agent like Soil Moist, which stores water, releasing it as necessary, and keeps the roots from overheating.
Once the plants are in place, top dress the soil with gravel, bark, or another mulch material. "I like to use green moss," says Roger. "It's attractive, natural, and helps keep in the moisture."
Place the pot atop terra-cotta, brick, or plastic spacers to assist drainage and allow air to circulate beneath.
A porous hand-molded concrete pot holds a combination of coleus
, flowering maple, spider plant, and holly fern.