This experiment is so satisfying because it shows great results in just a few hours. Demonstrate how stems transport liquid with the classic celery experiment, and then extend the experiment with a couple interesting variations.
First off, pick celery with leaves still attached, as it will quicken the process and also show more dramatic results. Cut the bottom of the stalk off, as it will draw in water better. Also, blue and red food dye turn out to be the most visible on the celery. Place celery in water with food dye and check on it in a few hours, and then also check on it the next day. The celery will appear to have stripes, as the xylem (special tubes in all plants to transport water) have absorbed the colored water to transport it up the stem. Cut one piece in half to see the xylem even better.
After performing the classic experiment, try some of these variations:
**Place the piece of celery that has already absorbed one color into another color of water. Make predictions as to what will happen and then watch as it turns into a new shade, a mixture of the two colors.
**cut the bottom of the celery celery stalk in half lengthwise and place each half into different colored water. Make predictions how the celery will react and then watch as half of the upper section turns one color and the other half turns the other color.
**try the experiment with several pieces of celery: one piece without leaves; one piece with leaves; and then one piece with leaves that you run a blowdryer on for several minutes. Make sure they are all the same length and don’t forget to make predictions. The leaves will absorb color faster than the ones without leaves. The blowdryer will simulate a hot summer day when water is evaporating from the leaves, forcing the leaves to draw more water from the ground. The celery with the blowdryer will absorb dye the fastest.
**try varying the length of the celery. Shorter pieces will bring the color to the top the fastest, since it has less length to travel.
- Re-Growing Celery: Grow a New Bunch Indoors or Outdoors (thekitchn.com)