Grow lettuce in a jar
NameDate started
This jar grows lettuce with no pump. The plant drinks the water down. Its top roots breathe in the air gap.
What you need
- A clean jar with a wide mouth (about 4 liters or 1 gallon)
- A lid with a hole that holds the net pot snugly
- A net pot that fits the hole (about 5 cm or 2 inches wide)
- A lettuce seedling in a starter cube (about 2 or 3 weeks old)
- A soil-free growing mix, like coco coir or peat with perlite
- Plant food made for growing in water (hydroponic plant food, not plant food for soil)
- Dark paper, cloth, or a sock to cover the jar
- A measuring cup and clean water
- A bright window, or a grow light
- A · lettuce seedling
- B · net pot
- C · roots
- D · plant water
- E · air gap
The dashed line is the waterline.
Build it
- Wrap the jar in dark paper so light stays out.
- An adult mixes plant food into clean water, following the label.
- Fill the jar with the plant water, almost to the top.
- Tuck the seedling into the net pot, with growing mix around it.
- Set the net pot in the lid so its bottom sits in the water.
- Put the jar in a bright spot, out of the rain.
Safety: An adult mixes the plant food. Plant food is not for eating or drinking. Wash your hands after you touch it.
What to watch for
- Weeks 1 and 2
- Roots grow out through the slots of the net pot.
- The water level starts to drop. That is the plan.
- Weeks 2 and 3
- The water drops below the pot. An air gap opens.
- Do not fill the jar back to the top.
- Week 4 and on
- Cut the lettuce when it is big enough to eat.
- If the jar may run dry, an adult adds a little water.
My jar, week by week
| Week | Water level (high, middle, low) | Leaves (how many, what color) | Notes |
|---|---|---|---|
| 1 | |||
| 2 | |||
| 3 | |||
| 4 | |||
| 5 | |||
| 6 |