Creating a stunning form garden in outdoor plant boxes is a fantastic way to add structure and beauty to your outdoor space. Whether you're a seasoned gardener or a beginner, selecting the right plants is key to achieving a cohesive and visually appealing design. Here are some of the best plants to consider for your form garden in outdoor plant boxes:

1. Boxwood (Buxus sempervirens) – A classic choice for form gardens, boxwood is evergreen, easy to shape, and perfect for creating hedges or geometric designs in plant boxes.

2. Lavender (Lavandula) – With its fragrant purple blooms and silvery foliage, lavender adds both color and texture to your garden while maintaining a neat, structured form.

3. Dwarf Japanese Maple (Acer palmatum) – Ideal for adding height and elegance, this slow-growing tree offers stunning foliage and works well as a focal point in larger plant boxes.

4. Rosemary (Rosmarinus officinalis) – This aromatic herb is not only useful in the kitchen but also great for form gardens due to its upright growth habit and ability to be pruned into shapes.

5. Ornamental Grasses (e.g., Festuca glauca) – These grasses provide movement and contrast, perfect for softening the edges of your form garden while maintaining a structured look.

When designing your form garden, consider the size of your plant boxes, sunlight exposure, and maintenance requirements. Mixing different textures, heights, and colors will create a dynamic yet orderly display. With the right plants, your outdoor plant boxes can transform into a masterpiece of form and function.