How the Self-Watering System Works
The most interesting part of the project is understanding what happens after water is added to the reservoir. When the lower end of the cotton wick touches the water, the cotton fibers begin absorbing water. The water travels upward through the tiny spaces between the fibers. This process is called capillary action. As the water reaches the upper part of the wick, it comes into contact with the surrounding soil. The soil absorbs some of this moisture. The plant’s roots can then obtain water from the moist soil.
Understanding the Water Movement
The system can be understood in four simple stages.
Stage 1: Water Storage
The reservoir stores water below the plant.
Stage 2: Water Absorption
The lower end of the cotton wick absorbs water from the reservoir.
Stage 3: Water Transfer
Water travels upward through the wick.
Stage 4: Soil Moisture
The water reaches the soil, helping maintain moisture around the plant roots. This creates a continuous pathway between the water reservoir and the plant. However, the system does not mean that the plant will receive exactly the amount of water it needs at all times. Different plants, soils, wick materials, temperatures, and humidity levels can affect water movement. Therefore, the soil should still be checked regularly.
Testing the System
After several minutes or some time, gently touch the soil near the wick. It should gradually become moist. Observe the plant over the following days. If the soil remains extremely wet, the system may be transferring too much water. In that situation, reduce the amount of water in the reservoir, use a smaller wick, or improve drainage. If the soil remains dry, the wick may not be making proper contact with the water or soil. Check that the wick is positioned correctly. The size of the reservoir also matters. A larger reservoir can hold more water, while a smaller reservoir may need to be refilled more frequently. This makes the project a useful experiment. Students can change one variable at a time and observe how it affects plant moisture.
