Capillary action is a fascinating natural phenomenon where water moves through narrow spaces in plants, defying gravity. Outdoor plant boxes provide an excellent setting to observe this process. Here are some of the best plants for demonstrating capillary action:

1. Celery (Apium graveolens) – Its thick, fibrous stalks clearly show water movement, making it a classic choice for experiments.

2. White Carnations (Dianthus caryophyllus) – When placed in dyed water, the petals change color, visually demonstrating capillary action.

3. Lettuce (Lactuca sativa) – The leaves quickly absorb water, making it ideal for quick observations.

4. Balsam (Impatiens balsamina) – Its vibrant flowers and stems highlight water uptake effectively.

5. Sunflowers (Helianthus annuus) – Their large stems and rapid growth make them great for long-term experiments.

For the best results, use clear containers or transparent plant boxes to observe the water’s journey. This experiment is perfect for educators, gardening enthusiasts, and curious minds alike!