Responses of Common Pot Grown Flower Species To Commercial Plant Growth Media Substituted With Vermicomposts

Waste management is an increasingly important problem in many developed countries and much effort is currently being expended into identifying novel uses for waste products. We consider the effects of substituting proportions of earthworm-digested composted green waste (vermicompost) into commercial peat based growing media on the germination, growth, and productivity of Helianthus annuus, Cosmos bipinnatus and Eschscholzia californica. The percentage germination, time to flowering, seed production, overall heights and biomass were measured for all three species in treatments of commercial peat based growing media where the growth medium was substituted with vermicompost at rates of 0%, 20%, 40%, 60% and 100%. In addition, the total numbers of inflorescences was recorded in multiple flowering species. Results for Helianthus suggest that while vermicompost additions induced small species specific growth responses in germination rate, growth rate, overall height and total biomass, none were statistically significant. For Cosmos there was a significant increase in early plant growth rate and in the final flower numbers at substitution rates of 20% and 40% vermicompost. The total biomass and numbers of flowers produced by Eschscholzia was decreased significantly by substitution of 20% and 40% vermicompost. We conclude that the plant growth enhancement properties of this vermicompost seem more species specific than previously reported. Further, in order to preserve consumer confidence in waste-derived horticulture products, vermicompost marketing strategies should acknowledge these findings.