Premier Pro-Mix BX Mycorrhizae 3.8 cu ftPro 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