Terrarium soil is a hand blended mix of vermiculite, coco coir, worm castings and premium fine blend potting mix. This blend combines the 5 most vital components of a healthy soil mix: Aeration: Oxygenates the plant root system. Water retention: Makes sure the plants are hydrated correctly and encourages transpiration. Drainage: Helps prevent root rot. Nutrition: Healthy plant growth and lush foliage. Soil Fertility: Excellent at holding, storing and releasing nutrients when required.