Creating a gradation garden in outdoor plant boxes is a fantastic way to add visual interest and depth to your outdoor space. The key to success lies in selecting plants that transition smoothly in height, color, and texture. Here are some of the best plants to consider for your gradation garden:

1. Tall Backdrop Plants: Start with taller plants like ornamental grasses (e.g., Miscanthus) or shrubs (e.g., Boxwood) to create a structured backdrop.

2. Mid-Height Fillers: Add medium-sized plants such as Lavender, Salvia, or Coreopsis for vibrant color and texture.

3. Low-Growing Edgers: Finish with ground-hugging plants like Creeping Thyme, Sedum, or Alyssum to soften the edges and complete the gradation effect.

For a cohesive look, choose plants with complementary colors and varying bloom times to ensure year-round appeal. Additionally, consider the sunlight and water requirements of each plant to ensure they thrive in your outdoor plant boxes. With careful planning, your gradation garden will become a stunning focal point in your outdoor space.