Celery and food coloring lab
01 // Question
How does water temperature change how fast colored water travels up a celery stalk?
A testable question names one thing you change (water temperature) and one thing you measure (time or distance).
02 // Variables
Independent
Water temperature- Cold water
- Room-temperature water
- Warm water
Dependent
Speed color travels up the stalk- Hours until color reaches the leaves
- Height of visible color at 24 hours (cm)
03 // Hypothesis
IF a celery stalk stands in warmer colored water, THEN the color will reach its leaves faster, BECAUSE warmer water moves through the stalk's narrow vascular tubes more quickly, the same tissue a living celery plant uses to pull water up from its roots.
04 // Procedure
1. Trim the stalks
Cut a fresh slice off the bottom of each celery stalk just before starting, so the vascular tubes are freshly open.
2. Color the water
Add the same amount of food coloring to equal volumes of water at each test temperature.
3. Stand the stalks
Place one celery stalk in each cup of colored water, leaf-end up.
4. Check periodically
Check every few hours and record when color first becomes visible in the leaves.
5. Measure the height
At 24 hours, measure how high up the stalk the color has traveled.
05 // Data table
| Water temperature | Color visible in leaves (hrs) | Height of color at 24 h (cm) |
|---|---|---|
| Cold | ____ | ____ |
| Room temperature | ____ | ____ |
| Warm | ____ | ____ |
06 // What to expect
Warmer water usually reaches the leaves fastest, because heat increases the rate of water movement through the celery's xylem — the narrow tubes that carry water from a plant's roots up to its leaves in a living plant.
The color appears as thin lines running the length of the stalk rather than spreading evenly, because it's traveling through distinct bundles of vascular tissue rather than soaking through the stalk as a whole.
07 // Lab notes
- Use fresh celery with the leafy top still attached — the color is easiest to see there.
- Cut a fresh slice off the bottom right before placing it in the water, since a stalk that's been sitting can have tubes partly blocked by air.
- Food coloring can stain hands and countertops — work on a covered surface.
08 // Remember
Celery has plumbing. Colored water traces the exact tubes a living plant uses to move water from roots to leaves.
09 // Questions people ask
Why does colored water travel up a celery stalk?
Celery, like other plants, has vascular tissue called xylem — narrow tubes that carry water and dissolved nutrients from the roots up to the leaves. A cut stalk standing in colored water pulls that water up through the same tubes, and the dye moves along with it, making the normally invisible tubes visible.
How is the celery experiment different from the walking water experiment?
Both involve water moving through narrow channels, but the walking water lab moves water through the physical gaps between paper towel fibers, while the celery lab moves water through a living plant's actual vascular tissue — the same biological structure a growing plant depends on.
Why does the color appear as thin lines instead of coloring the whole stalk?
The dye is traveling specifically through celery's vascular bundles, which run in distinct strands the length of the stalk rather than being spread evenly through all of its tissue. That's why the color shows up as visible streaks rather than an even tint.