Hydrosorb helps keep moisture and nutrients available in the root zone for longer periods of time. When mixed with your potting soil it acts like a sponge and releases water when your plants need it, whether you're home or not. Made from a super-absorbent polymer gel that is non-toxic to animals or humans. Use only 1/2 teaspoon per 4 inch pot. Perfect for container plants and it does not need to be replaced for up to 5 years.