Creating a rainbow-themed outdoor plant box is a fantastic way to add vibrant colors and visual appeal to your garden. To achieve this, select plants that represent each color of the rainbow. Here are some top choices:

1. Red: Geraniums or Red Salvia – These bright red flowers are eye-catching and easy to grow.

2. Orange: Marigolds or California Poppies – Their warm orange hues bring energy to your plant box.

3. Yellow: Sunflowers or Coreopsis – These cheerful yellow blooms add sunshine to any space.

4. Green: Ferns or Sweet Potato Vine – Lush green foliage provides a perfect backdrop for other colors.

5. Blue: Lobelia or Blue Salvia – These cool-toned flowers create a calming effect.

6. Indigo/Violet: Lavender or Petunias – Deep purple shades add richness and depth.

For a cohesive look, arrange the plants in rainbow order and ensure they receive adequate sunlight and water. This setup not only beautifies your outdoor space but also attracts pollinators like bees and butterflies. Happy gardening!