Vermicompost and biochar as substitutes of growing media in ornamental-plant production

Vermicompost is a product derived from the accelerated biological degradation of organic wastes by earthworms and microorganisms. Biochar is a by-product of the C-negative pyrolysis technology for bio-energy production from organic materials. Containerized plant production in floriculture primarily utilizes substrates such as peat moss. Environmental concerns about draining peat bogs have enhanced interests in research on complementary products that can be added to peat. A comparative greenhouse study was conducted to assess the suitability of biochar (B) and vermicompost (V) as partial substitutes for peat-based growing media for ornamental plant production. Different blends of B at a volume fraction of 0, 4, 8, 12 % and V at 0, 10, 20, 30, 40, 50 % were compared to a baseline peat substrate (S) as control in the cultivation of geranium (Pelargonium peltatum) and petunia (Petunia hybrida). Substrates were characterized for physical and chemical properties, plant growth, and flower production. Mixtures with low-medium V levels (10 -30%) and high B level (8-12 %) in Petunia and Pelargonium induced more growth and flower production than that of the control. The results obtained with different B and V associations are of interest to those who want to reduce peat consumption for the production of ornamental plants in containers and to reduce carbon footprint of this commercially productive sector.