Celery Science Experiment 🌈 ages 3 🌈 For this simple experiment, all you need are some leafy celery stalks (the inner stalks work best), water and food coloring. Add food coloring to each glass of water. (We made red, orange, blue and black.) Then add the celery stalks. Cut about an inch off of each stalk before placing in water. After 24 hours the leaves will have changed color to match the water. This is because the tiny tubes (xylem) in the plant drink up the water just like a straw. This p