By Sam Burbach, Education & Programming Coordinator – 04/17/2020
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Need a science project to do at home with the kids? Or do you maybe have a hard time caring for houseplants – either overwatering them or forgetting about them altogether and not watering them until they’re completely wilted? Whether you’re looking for a fun project to do or want a way to keep your houseplants perfectly watered, making recycled self-watering planters is an easy project to try at home!
First, we need to understand how self-watering planters work, and this makes a great science lesson for kids! Self-watering planters work through a process called capillary action, or wicking, which is the same process that plants use to bring water from the ground, up through their roots and all the way up to the highest point of the plant, despite the force of gravity which should pull the water down.
The most basic way to see capillary action in action (no pun intended!) is to dip the corner of a paper towel into a dish of water (colored water makes it even easier to see). The water spreads up through the paper towel as far as it can go until the force of gravity is too strong and the water can no longer climb any higher. While this doesn’t necessarily explain how capillary action works, it is a good visual to show how our self-watering planter is going to work. (If you want to continue with a lesson about capillary action, click here for a more in-depth explanation.)
This self-watering planter uses a wick that will serve as a bridge between a water source and the potting soil. As the plant takes up water through its roots, more water will climb up the wick through the process of capillary action (like how the water climbed up the paper towel), thus making sure the potting media is consistently moist. Watering plants through this method ensures that the roots are evenly moist, promotes deeper root growth, and makes sure the plant does not go through periods of dryness and flooding.
Here’s how you can try it at home!
Here’s what you’ll need:
- Plastic bottle – 2-liter bottle, water bottle, etc. (something with a shorter “neck” area – I tried this with an orange juice bottle and the shape didn’t work)
- Scissors or utility knife
- Wick material: String/yarn or fabric (scrap fabric, t-shirt scrap, holey sock!, etc.)
- Potting mix
- Seeds or small plant – something that likes to be consistently moist (cilantro, parsley, mint, African Violets, spider plant, etc.)