When it comes to framing gardens in outdoor plant boxes, selecting the right plants can transform your space into a lush, visually appealing retreat. Here are some of the best options to consider:

1. Boxwood (Buxus sempervirens) – A classic choice for structured borders, boxwood is evergreen, easy to trim, and adds a formal touch to garden edges.

2. Lavender (Lavandula) – Perfect for a fragrant and colorful border, lavender thrives in sunny spots and attracts pollinators.

3. Japanese Forest Grass (Hakonechloa macra) – This ornamental grass adds soft, flowing texture and works well in shaded or partially shaded plant boxes.

4. Dwarf Alberta Spruce (Picea glauca 'Conica') – A compact evergreen that provides year-round structure and a neat, conical shape.

5. Heuchera (Coral Bells) – With vibrant foliage in shades of purple, red, and green, heuchera adds a pop of color to garden borders.

6. Sedum (Stonecrop) – Drought-tolerant and low-maintenance, sedum varieties like 'Autumn Joy' offer seasonal interest with their blooms.

For a dynamic look, mix flowering perennials with evergreens to ensure year-round appeal. Whether you prefer formal hedges or relaxed, flowing borders, these plants will help you create a stunning garden frame in your outdoor plant boxes.