These are planters made from 1, 2 and 3-liter pop bottles. Use them and you will be reading a Rosetta stone of sub-irrigation (known incorrectly as "self-watering" in the consumer market).
Use them and you will soon be growing superior plants while learning more about capillary action and how plants function. Use them to teach your children too. What they will learn is about science, not just gardening.
Capillary action is the basic function behind all so called "self-watering" planters whether they be for decorative house plants or vegetable growing. Learn about capillary action by observing it at work in these clear bottle planters. What you will observe and learn is applicable when growing all terrestrial plants whether indoor or outdoor.
Think I'm over dramatizing? You will discover that I'm not when you try them yourself. Remember that they are FREE! In fact, you get some extra points for doing some social good by keeping them out of the waste stream.
I have been studying sub-irrigation watering methods for more than 30 years. It started in my interior plantscaping business back in the '70's. Sub-irrigation revolutionized the way we did business. Our quality went up along with customer satisfaction, while our replacement rate went down. It was a lot easier to train new employees too.