Recycled Plastic Bottle Planters Using the Sub-irrigation Planter(SIPS) Method

Tutorial and many images for plastic bottle inspirations here.

Image source here.

This is super for young science students learning capillary action.

"How Sub-irrigation and Automatic Indoor Self Watering Containers Work

Water is added to a reservoir; the plant pulls moisture upward through the entire root ball through capillary action, like a sponge. The amount and evenness of the water movement from the sub-irrigation reservoir to the growing medium depends on the growing medium mix and its degree of compaction and/or breakdown."

A simple way to do this with house plants is to put a potted plant with drainage holes within a larger pot with no holes; raise it a bit off the bottom with some random stones or an upside down bowl(anything that lifts it up), and add water to the outer pot only. The water should be higher than the potted plant within, about 1/4 of the way up. You can add more water, but I've found that the water stays fresher if you fill it more often, and not let it sit for long periods as it would with a higher level of water. I've done this successfully with an African Violet.

More on garden SIPS here.