Biochar has long been proposed to be a substitute for peat in soilless mixes for greenhouse growing. Low levels of biochar have been shown to increase disease resistance, increase nutrient supply and uptake, and immobilize phytotoxic substances. Due to its high porosity and pH, biochar has the potential to provide an ideal habitat for mycorrhizal fungi to partner with plant roots. This study examined how various mycorrhiza sources interacted with different biochar rates to effect geraniums (Pelargonium x hortorum L. ‘Maverick Red’). Four different mycorrhizal sources were used in addition to a control containing no mycorrhiza: two commercial sources, MycoBloom and BioAg Vam-Endo, spores extracted from agricultural soils, and spores extracted from prairie soil, with four biochar rates implemented: 0, 15, 30, and 45%. Media with biochar incorporated remained saturated for longer periods after irrigation than pots filled with straight BM-7 peat-media. Prairie soil combined with 15% biochar-BM7 media formed buds and began to flower before all other treatments. Results suggest that biochar and mycorrhiza may pair well to improve potted plant growing.
