Plant growth in a sealed jar

Plant bean seeds in a sealed mason jar. Watch them sprout and grow leaves, entirely from the CO2 in the jar and sunlight.
Science content
Biology: Features, Adaptations of Living Things (K, 1, 3, 7)
Biology: Life Cycles (2)
Biology: Food Webs, Ecosystems, Biomes (3, 4)
Earth/Space: Sustainable practices, Interconnectedness (2, 5, 7)
  • large, fast-germinating seeds e.g. runner bean seeds
  • small tub of water
  • large mason jar with sealing lid
  • potting soil mixed with sand, to fill the mason jar a few cm
  • a little water
  • a light, but not too hot, spot to leave the jar

Add 4 or 5 bean seeds to a tub of water overnight or for a couple of days, until the seed coats start to split.
The seeds can be planted directly in the soil at this point, or for faster visible results in the jar, sprout the seeds before planting: Layer the seeds between lightly-dampened paper towels and seal in a baggie to keep the moisture in. Sit in a dark place (e.g. wrapped in a dark tea towel) for up to four days, until a root has started to emerge.

Add the potting soil/sand mixture to the mason jar and stir in a little water to make moist but not soggy.
Make four or five dents in the soil and carefully lay the sprouted bean seeds in them (do not break the root tip).

Optionally, have students breathe some carbon dioxide (in their exhaled breath) into the jar, for reinforcement that the plants will need the CO2 contained in the jar.
Seal the mason jar and place in a light, but not hot, place in the classroom.
Within a week, leaves will start to emerge. Speed of growth depends on the temperature of the classroom.

Once visible growth has happened in the jar, the beans can be planted in a garden. Usually about a week.
The contents of the sealed jar will become stinky, and the beans will start to rot, if left for too long. (This happened after two weeks for us.)

The seeds grow into a plant, using only the air and water in the jar, and the energy of the sunlight that hits the jar.
Plants build their structure from CO2 and water. (They also respire, using oxygen in the jar.)
Plants remove carbon dioxide from the air, hence today's focus on reforestation and tree planting.


This activity from:…
This activity includes weighing the jar at the start and end of the activity - it is the same weight, as the bean seeds used CO2 that was already in the jar.

Grades taught
Gr 2
Gr 3
Gr 5
Gr 6