Celery in coloured water: how plants move water

The idea

Water travels up a plant through fine tubes to the leaves, which is how a plant gets the water it needs; in celery those tubes run up the crisp leaf stalk.

What you need

• Three fresh celery stalks with leaves, ends freshly cut
• Three clear cups with 100 mL of water each, coloured with 10 drops of red, blue and no food colouring
• A hand lens; a plastic knife for the adult to cut cross-sections
• Recording sheet with drawing boxes for 1 hour, 3 hours and next morning

How to do it

1. Predict where the colour will go and draw it.
2. Stand one stalk in each cup. Note the time.
3. After 1 hour and after 3 hours look at the leaves and the outside of the stalk. Draw what you see.
4. Next morning look again. The adult cuts 2 cm off the bottom of each stalk and then a slice from halfway up; look at the cut face with the hand lens.
5. Compare the red, blue and plain stalks.

What you should see

By the next morning the leaf veins and leaf edges of the red and blue stalks are tinted, and the U-shaped cut face shows separate coloured dots near its ribbed outer side, each just inside one of the stalk's strings (the dots are the water-carrying tubes), with the rest of the stalk uncoloured; the plain-water stalk shows no colour. A faint tint may show in the lowest leaves within 3 hours; the overnight result is the reliable one. The learner knows it worked when the coloured dots appear only in the coloured cups' stalks.

What changes

What you change

colour of the water (red, blue, none)

What you measure

where colour appears and when

What you keep the same

• same celery bunch
• 100 mL per cup
• same room
• same observation times

Common misconceptions

Each of these ideas is wrong, and the activity is a chance to test it.

• Plants drink through their leaves.
• The colour spreads through the whole stalk like a sponge (it stays in the tubes).
• The crisp part of celery is the stem (it is the leaf stalk; the tubes run up it just the same).

Safety card

Curriculum references

The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.

• Science and Technology K-6 Syllabus (2017), NESA. Current syllabus; NESA's timeline is 2026 plan and prepare, 2027 start teaching the 2024 syllabus. Code read from the official syllabus document on 2026-09-22.STe-3LW-STSTe-1WS-S
• Science and Technology K-6 Syllabus (2024), NESA. Implementation from 2027, so this code describes the future syllabus. Code read from the outcomes page on 2026-09-22.STE-SCI-01STE-PQU-01
• Australian Curriculum v9AC9SFI01AC9SFI02AC9SFI03AC9SFI05

Sources

The pages the author read to write this activity.

1. www.nsw.gov.au/education-and-training/nesa/curriculum/science/science-and-technology-k-6-2017
2. curriculum.nsw.edu.au/learning-areas/science/science-and-technology-k-6-2024/content/early-stage-1
3. primaryconnections.org.au/teaching-sequences/year-1/survive-thrive
4. primaryconnections.org.au/v84-sequences/growing-well
5. en.wikipedia.org/wiki/Celery