Creating a natural privacy screen in outdoor plant boxes is an excellent way to enhance both aesthetics and functionality in your garden or balcony. The best plants for this purpose are those that grow tall, dense, and require minimal maintenance.

1. Bamboo: Fast-growing and evergreen, bamboo is ideal for quick privacy. Clumping varieties like *Bambusa multiplex* are non-invasive and perfect for plant boxes.

2. Boxwood: These evergreen shrubs can be trimmed into neat hedges, offering year-round privacy. Dwarf varieties like *Buxus sempervirens* work well in containers.

3. Arborvitae: A classic choice, *Thuja occidentalis* grows upright and forms a thick green wall. It’s cold-hardy and low-maintenance.

4. Privet: Known for its dense foliage, privet (*Ligustrum*) can be pruned into shapes and thrives in plant boxes with proper care.

5. Italian Cypress: These slender, tall trees (*Cupressus sempervirens*) add vertical privacy and a Mediterranean touch.

For added beauty, mix flowering plants like hydrangeas or oleanders, which also provide seasonal color. Ensure your plant boxes have good drainage and use quality soil to support healthy growth. With the right plants, you can transform any outdoor space into a private, lush retreat.