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3. Plants need Water

Plant growth and quantities of water


1. Mix about 5 gallons of Grow nutrient solution. Food coloring is added to the water to make it easier to see. Groups can have different colors of water.

2. Divide the students into four groups.

3. Give each group of students 6 plastic drinking cups (clear about 16 ounce).

4. Have each group measure and mark each cup along side in increments of 1 inch. Then label each cup, 0 inch,1 inch, two inch, up to five inches.

5. The students fill each cup with propagation grade perlite, to about 1 inch from the top.

6. The students measure out nutrient water and pour tablespoon by tablespoon until the water level gets to be about the mark of one of the inches. Then each cup is marked with a long line at the level of the water. The number of tablespoons used is recorded.

7. The cups are all placed in a sunny location (a south facing window or under a plant growing light.

8. Seedings (about 2 inches tall, beans if available), are transplanted into each cup.

Each day, at the beginning of the class period, a line is marked on the cup at the new water line.

    Information is recorded in the notebook
  • 1. Drawing of the plant each day.
  • 2. Inches of water level.
  • 3. Size of plant tallest point.

Experiment continues until the plants have used their water.

At the end make a comparision between the quantities of water used and plant growth.

Qualities of water

Instructions for the experiment

1. The students each have four 1 quart bottles.

    they fill bottles with
  • a) a soda pop
  • b) tap water
  • c) distilled water
  • d) Grow nutrient water
The class then has another 6 bottles that they can use for other things. They can come up with suggestion.

Each bottle is labeled.

Note: The students might suggest a nutrient made from animal manures or even human urine. These suggestions are important and very correct. With the exception of fish water, these experiments are not recommended in the classroom setting due to social constraints.

However, the student making the suggestion should bring up a general topic of nutrient rich waste waters.

This discussion is only to validate the topic, and to then point out that these experiments cannot be done in the classroom, and should be saved for a lab where the experimenters can be safe from possible disease.

2. 12 Grow cups are set up along the sun shelf or under the grow light.

3. Small plants are transplanted into a perlite media.

4. Each plant is carefully watered with the chosen nutrient water.

5. Each day a record is made in their labbook of the plant, how it looks, measuring, and water used.

Revised: 1 May 2016
Copyright © 2016 Institute for Simplified Hydroponics