Back to the Roots 100% Organic Seed Starting Mix block expands into 12 quarts cubic feet of rich, fluffy, and nutrient-rich soil when you add water. Perfect for indoor and outdoor use, it enhances water retention and aeration, promoting healthy root growth and robust plant development. Say goodbye to heavy, messy soil bags — our coir brick is convenient to store and easy to use. This natural and sustainable substrate is your key to thriving plants and more vibrant potted plants and gardens.