Retain - Water Retention Soil AdditiveRetain plant crystals are a safe and easy to use soil additive made out of water absorbing ingredients (cross linked polyacrylate, bentonite clay, lava rock and silicates) that absorbs up to 40x its own weight in water. 50 lbs of retain can hold up to 250 gallons of water. It increases the water holding capacity of soil by up to 60%, helping to prevent waterlogging and releases the water to plants, minimizing evaporation, especially in hanging baskets