Pumice is a relatively lightweight volcanic rock used as an amendment in all types of soil. Its porous composition allows it to retain moisture and nutrients during watering, then release them slowly over time as the root system requires. Think of it as a battery for your plants! Pumice is a relatively lightweight volcanic rock used as an amendment in all types of soil. Its porous composition allows it to retain moisture and nutrients during watering, then release them slowly over time as the root system requires. Think of it as a battery for your plants! Terrain is a garden and home brand deeply rooted in nature and plant life. From weather-ready planters and outdoor furniture to artisan-made wreaths and hand-poured candles, their curated product assortment explores the boundaries of life lived outside and in. With a globally conscious, locally influenced point of view, Terrain offers inspired seasonal solutions for creative living, gathering, and gardening.