Crystal Soil is a unique and fascinating growth medium for plants. This remarkable hydro-gel is designed to store water and plant nutrients and to release them as required by the plant. Students will be captivated by the bright colors and they will be able to observe the plant roots as they develop and grow. Enriched with balanced nutrients Crystal Soil requires no fertilizer and needs to be watered only once every 3-4 weeks! Four colors available. The 2.5-ounce package is concentrated-when water is added it expands to a full quart.