The most important feature of any gardening container is the drainage holes in the bottom. Roots will drown in containers without drain holes. When planting your container, select commercial growing medium. Garden soil does not drain well enough to function in a container situation. The lightweight commercial materials can be used right from the bag, are sterile, and generally supply the right amount of aeration and moisture retention as well as fertilizer to get the plants started.
Water is the most limiting factor in having a successful container garden.
Water thoroughly, saturating the growing medium completely until you see water coming out of the drainage holes in the bottom of the container. This excess water pushes harmful fertilizer residue and mineral salts form the growing medium. Discard any water the passes through the container and do not let it be absorbed back into the medium. To aid in moisture retention apply a mulch on the surface of the medium. Since each watering will push some plant nutrients from the root zone, it is advisable to fertile at each watering.