Place a tray underneath if seepage will stain your deck or patio. Containers should not rest in standing water for long, as roots may begin to rot. Container soil must be able to hold water and nutrients, yet drain well. It is best to water containers first, before applying liquid fertilizer. If you incorporate crystal soil polymer when mixing your planting media, it will store water better and not dry out in the summer heat.
Containers look best when they are packed with plants, with little or no soil visible.
It is difficult to place plants too closely together in containers. A planted container should look attractive immediately after or certainly within a few weeks of planting. Alpine troughs and 'arid gardens', by contrast, look best if the little mounding plants are placed with an inch or two in between. Try mulching the soil with inch of washed gravel, sand or small stones to give an alpine look. To determine when to water, just stick your finger into the soil.