A dish garden simply put is a group of plants planted in a shallow container.
Because the container is shallow plants for your dish garden should have a shallow root system and be slow growing. The plant that fits this description perfectly for a dish garden is a cacti or succulents.
A wide shallow container will work , the shape is not of any significance. It can be of whatever material you like because there is no drainage hole. You can use clay, plastic, glass, glazed ceramic or metal
You can buy premixed potting made especially for cactus or you can mix your own. Mix an equal amount of basic potting mix with sand for fast drainage.
In your container add a good drainage layer of pebbles or marbles you don't want your plants sitting in too wet of a soil which will kill them.Any excess water will drain down through the sandy soil and collect at the bottom of the container. On top of the pebbles you add a thin layer of charcoal which keeps the soil smelling sweet. Finally you add your damp potting soil on top.
Remove the cacti from their pots one at a time, remember to wear your gloves. Make a valley in the soil and set the plant in, push the soil firmly around, put all your plants in the same way. After you have arranged your plants you can add colorful rocks on top of the soil for decoration.
Cactus plants need bright sunlight, so you will need to find a place in the sunlight to put your dish garden. Water carefully, cacti are desert plants so they don't need too much of water.