The Influence of Vermicompost in a Plant's Growth

African Violets

• Beginning with pioneering work by Mary Appelhof, a Michigan-based biologist, in the 1970s, soil researchers around the world have confirmed the beneficial influence of vermicompost on plant growth. In "Worms Eat My Garbage," Appelhof describes tests in Michigan of the growth of African violets grown in potting soil, pure vermicompost, and a blend of 1/3 each of potting soil, vermicompost and perlite. "Leaves were larger, greener and more robust" in the latter group, she wrote.

Other Plants

• In 1980, soil ecologists Clive Edwards and Ian Burrows paralleled Appelhof's work in England and would later join vermicomposting conferences sponsored by the biologist. Edwards and Burrows tested ornamental shrubs; vegetables including eggplants, cabbage, peppers, cucumbers, lettuces, radishes and tomatoes; and bedding plants ranging from French marigolds to asters, alyssum, salvia and sweet peas. They grew the plants in commercial plant growth media with inorganic nutrients and in vermicomposts created from animal waste feedstocks. Seeds germinated more quickly, and plant growth was stronger, in plants grown in various mixtures of vermicompost and peat. Plants that grew particularly well in a vermicompost-peat mixture in a pot included eggplants, peppers, dahlias, coleus and petunias.

Greenhouse Uses

• Professor Norman Arancon of the University of Hawaii notes positive results of vermicompost in greenhouse experiments in the chapter "The Potential of Vermicomposts as a Plant Growth Media for Greenhouse Crop Production" in the "Vermiculture Technology." Even as little as 5 percent of vermicompost added to plant growing media spurred growth, he concluded based on a survey of around 70 articles published in scientific publications. Rates of 40 to 60 percent of vermicompost often resulted in the optimum growth of peppers, tomatoes and other plants, with greater plant heights and leaf areas recorded for tomatoes and more flowers recorded for petunias.

Field Crops

• Arancon and Edwards teamed up on another chapter in "Vermiculture Technology" to look at "The Use of Vermicompost as Soil Amendments for the Production of Field Crops." Tests of peppers, tomatoes and strawberries in the field showed stronger results for vermicompost application than for inorganic fertilizers. Strawberry plants showed 35 percent or more increases in leaf areas, number of flowers, numbers of plant runners, plant-shoot biomass and marketable fruit weights, the authors noted. Application rates in the field remain more complex to determine than in greenhouse-grown plants, they write, noting that aqueous teas used to drench the soil may prove easier for the grower than granular vermicompost.