Creating a refreshing outdoor plant box requires selecting the right plants that thrive in shade and resist heat while adding a cooling effect to your space. Here are some top choices:

1. Ferns: Known for their lush, feathery foliage, ferns like Boston Fern or Maidenhair Fern thrive in shaded areas and add a cooling, tropical vibe.

2. Hostas: These shade-loving plants come in various sizes and colors, offering dense foliage that helps lower surrounding temperatures.

3. Coleus: With vibrant leaves and a preference for partial shade, coleus plants are perfect for adding color while staying heat-tolerant.

4. Sweet Potato Vine: This fast-growing trailing plant provides ample ground cover, reducing heat absorption and keeping the area cool.

5. Lamium (Dead Nettle): A low-maintenance option with silvery leaves that reflect sunlight, making it ideal for cooler plant boxes.

For optimal results, combine these plants with proper drainage and occasional misting to enhance their cooling effects. Whether for a balcony or patio, these selections will transform your plant box into a serene, green retreat.