Differential Impacts of Growing Medium on Micro Greens Productivity

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2017: $7,458.00
Projected End Date: 07/31/2019
Grant Recipient: McEvilly Gardens LLC
Region: North Central
State: Indiana
Project Coordinator:
Thomas McEvilly
McEvilly Gardens LLC


  • Agronomic: Micro greens


  • Crop Production: Growth mediums

    Proposal summary:


    The issue I have identified is growing medium sustainability. Most growers I personally know are growing in mediums primarily composed of peat. The use of this medium is a one-time use. This is wasteful, inefficient and damaging to the environment.

    Peat moss is mined, which involves scraping off the top layer of living sphagnum moss. The sphagnum peat bog above the mined product is a habitat for plants like sundews, butterwort and bog rosemary, as well as rare and endangered animals like dragonflies, frogs and birds, not to mention the living moss itself. Manufacturers' claims that the bogs are easy to restore, the delicate community that inhabits the bog cannot be quickly re-established. Peat moss is a slowly renewable resource, but it can take hundreds to thousands of years to form. Like all wetlands, peat bogs purify fresh air and even mitigate flood damage. In fact, peat bogs store about 10% of all fixed carbon.

    In the U.S., peat moss is almost exclusively used by the horticulture industry. 40,000 acres of sphagnum are currently being harvested in Canada, with 90% of the product destined for gardens in the U.S. In the U.K., where peat moss is burned as fuel, as well, nearly 94% of the lowland bogs have been altered or completely destroyed due to harvesting. And most of our peat is shipped hundreds of miles, often when it’s wet and heavy, which adds further to the fuel required for shipping.

    Many conservationists, gardeners, and wetlands scientists in these countries have recommended a boycott of peat. The Royal Horticultural Society hopes for a 90% reduction by 2010. Areas in Ireland have already banned the harvesting of peat moss altogether. I want to solve this issue or at least add to the body of knowledge for this issue.


    I intend to conduct an experiment to find more environmentally friendly and cost effective mediums for micro green production than the current standard of peat based systems. I have established constants, variables, and will post my observations. My hypothesis is that there must be a medium which is both more economical and environmentally friendly.

    My constants will be numerous. I will use the same seed sets from one supplier; I will provide all microgreens with the same amount of water and will track chemical composition through the office of my water provider on a weekly basis; all microgreens of the same type will receive the same amount and intensity of light. I will hold temperature as a constant. I will also control humidity.

    My only intentional variable is the growing medium. I have identified that following mediums to utilize: peat based (constant); shale rock; coconut coir; Grow Rock (Hydrocorn); Rockwool; a mix of perilite, vermiculite, and sand. Each trial will be thirteen weeks and involve the constant and three variable mediums. I will repeat each trial twice.

    Project objectives from proposal:

    1. Identify a microgreens growing medium more economical and environmentally friendly than a soilless mix.
    2. Protect peat moss environments in Canada and associated flora and fauna by identifying an alternative microgreens growing medium.
    3. Lower commercial crop production cost of microgreens.
    4. Empower kids and their families to grow low cost, nutritious, economically sound and ecologically friendly food.
    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.