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), horticultural-grade perlite, horticultural-grade vermiculite, dolomitic and calcitic limestone (pH adjuster), wetting agent and mycorrhizae ? endomycorrhizal fungi (glomus intraradices).