A small garden that has everything at the same height – all low ground plants, for example – can look a bit flat, almost like a carpet. When you introduce different heights, you create layers that make the space feel richer and sometimes even bigger.
Taller plants at the back, medium ones in the middle and smaller plants or ground covers near the front build a gentle “staircase” for the eye. You see depth instead of just length or width.
You can also use pots on stands, hanging baskets, or small trees and shrubs to achieve this layering in tight spaces. Even a single taller plant can change the way the area feels.
The idea is similar to arranging people in a group photo. If everyone stands in one straight row, it’s okay. If some sit, some stand, and some are slightly behind, the picture looks more interesting.