Creating a Planck star-themed outdoor plant box is a unique way to blend astronomy and gardening. To achieve this celestial look, opt for plants that evoke the mystery and beauty of the cosmos. Silver foliage plants like Dusty Miller or Artemisia mimic the shimmer of distant stars, while deep purple flowers like Petunias or Lavender add a cosmic hue. For a touch of otherworldly glow, consider bioluminescent plants like Moonflowers, which bloom at night. Succulents such as Echeveria 'Black Prince' or Haworthia resemble miniature planets, perfect for a starry theme. Complete the setup with twinkling LED lights to mimic a starry sky, transforming your plant box into a mesmerizing Planck star garden.