Ferti-Lome Horticultural Vermiculitefertilome Vermiculite is the mineral Mica, super heated to expand much like an accordion. This mineral is other used in soil mixes to increase water holding capacity. Many growers use vermiculite in their flats in order to create a micro environment that will protect seeds from air currents and insulate the seeds to provide uniform germination temperatures. 100% Horticulture grade Vermiculite Potting mix aggregate Seed cover Hydroponic media