Thigmotropism, the growth response of plants to physical touch, is a fascinating phenomenon easily observed in outdoor plant boxes. Certain plants excel at showcasing this behavior, making them ideal for educational or decorative purposes. Here are the best choices:

1. Sweet Pea (Lathyrus odoratus) – These fragrant climbers quickly wrap their tendrils around supports, responding to touch with rapid growth adjustments.

2. Morning Glory (Ipomoea purpurea) – Known for their vibrant flowers, morning glories exhibit strong thigmotropic responses as they spiral around trellises or fences.

3. Cucumber (Cucumis sativus) – Cucumber vines produce delicate tendrils that coil tightly around structures, making them excellent for demonstrating thigmotropism.

4. Passionflower (Passiflora spp.) – With intricate tendrils and rapid growth, passionflowers are both visually striking and highly responsive to touch.

5. Pole Beans (Phaseolus vulgaris) – Easy to grow, pole beans use thigmotropism to climb poles or strings efficiently.

For optimal results, provide sturdy supports like trellises or mesh in your outdoor plant boxes. Regular watering and sunlight will encourage vigorous growth, allowing you to witness thigmotropism in action. These plants not only beautify your space but also serve as living examples of nature’s adaptability.