Pro-Mix? BX Mycorrhizae is a general purpose peat-based growing medium containing, a beneficial mycorrhizal inoculum (Glomus intraradices). These microscopic fungi attach to and colonize the root systems working in symbiosis with plants. Contains: Canadian Sphagnum peat moss (75-85%/volume), Perlite?horticultural grade, Vermiculite ? horticultural grade, Dolomitic and Calcitic limestone (pH adjuster), Wetting Agent and Mycorrhizae ? endomycorrhizal fungi (Glomus intraradices).