Simply add water to the reservoir in the self-watering planter and your plants soak up the water as they need it automatically. Free shipping! This collection of planters represents the best in self-watering technology with their sub-irrigation system. As the plants drink the water in the soil, the soil pulls up the water from the reservoir automatically. No pumps needed - the soil's natural ability to hold water is all that these planters need to make maintenance a breeze. This ensures your plants get exactly the right amount of water all the time so no more worrying about over-watering. It also helps for going on vacation - depending on the plants and location you can sometimes go months without adding water.