Hydroponic experiments for kids

Below are some very inexpensive classroom projects. The experiments are meant as a fun introduction to hydroponics. We suggest that anybody new to hydroponics start with the 'soda bottle' experiment.

They will learn what you feed a plant matters more than what the plant grows in.

Plant for all experiments:
We suggest Swedish Ivy /Creeping Charlie. This plant seems to grow no matter what - we even rooted this one in a coconut pound cake ! The roots will set from the nodes. Put the cuttings in a glass of water and wait for roots to appear (aprox 2-3 weeks), then take them to your classroom. This way the students do not have to wait very long for the plants to start growing.

Other materials:
You need liquid hydroponic nutrient. Typically you only use 1-2 tsp per gallon, so a bottle goes a long way.
Each Soda bottle will also need a wick. You can purchase proper wicks or the students can bring in pieces of a cotton T-shirt. It could even be put to the student to find which fabric will be the best wick.
You will also need baking soda and lemons (or lemon juice). This is used to adjust the pH, so the plant can grow. Plants grow only between pH 5 and pH 7.
It would be helpful for you to buy a little pH test kit/ litmus paper- or you can ask the hydroponic store if they know what the pH is of your local water. If the pH is over 7: add ½ squeezed lemon per gallon water. If the pH is 5 or lower (unusual), add 1 tsp baking soda.
Ask each student to bring in an empty soda bottle and possible wick material.

General for all of the following experiments:
The soda bottles should have the top cut off and put back in the bottle up side down, as shown in the photo. The liquid the plant will be growing in should always be pH adjusted. If your tap water is fine, then adding the nutrient will not change the pH so much that you have to adjust it. If you are letting the student bring in 'home made' wicks, we suggest that the water level in the bottle always touches the bottle neck (which now hangs inside the bottle). This way we are sure the water gets up to the plant.

Fun Experiments:

For each Experiment you need to choose:

1. Growing media
2. Plant food mixture (also called nutrient solution)
3. What environment ? (Such as temperature, light, air)

The upside down soda bottle top is referred to as 'the container' in the following. The remainder of the bottle is 'the reservoir'.

Two Examples:

(1) Goal: You want to see the effect of light.
Set up 4 bottles each with the same growing media and each with the same plant food mixture (and same plant) . Now expose each bottle to different light.

(2) Goal: You want to see which growing media works the best.
Set up 5 bottles. Put a different growing media in each ‘container’. Use the exact same plant food mixture in each of the 5 bottles. Place all 5 bottle in the same place/same light.