When designing a balcony garden,go for cool colours like blue or violet for a serene environment. These colours will tend to recede from the viewer and make the space appear larger.
Extensive use of warm colours will make the space appear smaller. Use them sparingly as accents. For balance, combine upright plants with spreading and trailing ground covers proportionately.
Arrange the plants so that the tallest ones take the centre positions on planters, followed by the shorter ones along the edges.
If the planter is against a wall or at a corner, work your way from back to front, start with the tallest plants at the back.