These Self-Watering Pot Reservoirs convert your favorite pots into self-watering planters, keeping your plants healthy and reducing the time you spend watering. Just place this self-contained adjustable reservoir in the bottom of your pot, insert the refill tube and cover with soil. The One-Gallon Conversion Kit holds four quarts and fits pots between 16" and 20" in diameter at the rim. Simply fill the reservoir with water through the convenient Fill Tube. The soil will be moistened through evaporative action from the reservoir below. May be used with a liquid or a water-soluble fertilizer. A vacation watering solution!