Creating a beautifully shaped garden in outdoor plant boxes requires selecting the right plants that thrive in confined spaces while maintaining their form. Here are some of the best options for achieving stunning topiary effects:

1. Boxwood (Buxus sempervirens) – A classic choice for shaping, boxwood is hardy, slow-growing, and perfect for intricate designs.

2. Japanese Holly (Ilex crenata) – With small leaves and dense growth, it’s ideal for precise pruning and geometric shapes.

3. Dwarf Alberta Spruce (Picea glauca 'Conica') – A compact evergreen that naturally forms a conical shape, great for minimalist designs.

4. Lavender (Lavandula) – While not a traditional topiary plant, its fragrant foliage can be trimmed into rounded forms for a sensory garden.

5. Rosemary (Rosmarinus officinalis) – Another aromatic option that responds well to shaping, adding both beauty and utility.

For low-maintenance options, consider Sedum or Hebe, which offer interesting textures with minimal pruning. Pair these plants with well-draining soil and regular trimming to keep your outdoor plant boxes looking sharp and stylish. Whether you prefer formal hedges or whimsical shapes, these plants will help you craft a visually striking garden.