User/Grower Educational Materials and Training for Polyethylene Film High Tunnel Winter Production and Harvesting of Organic Salad Greens and Vegetables

Project Overview

Project Type: Research and Education
Funds awarded in 2002: $43,274.00
Projected End Date: 12/31/2006
Matching Non-Federal Funds: $20,000.00
Region: North Central
State: Michigan
Project Coordinator:
John Biernbaum
Michigan State University

Annual Reports


  • Vegetables: greens (leafy), radishes (culinary), turnips


  • Education and Training: farmer to farmer, workshop, youth education
  • Sustainable Communities: public participation


    Based on farmer experience and university research, a hightunnel/hoophouse (greenhouse) was constructed at Giving Tree Farm and Gunnisonville School, necessary equipment and seeds for cool season vegetable production were purchased, and crops were produced for sale or for school lunches. Training materials were developed and one or two day workshops including take home resources were presented to over 200 people. The outcome is a growing understanding of how protected cultivation in greenhouses can allow winter harvesting to support local food and school gardens. Course materials are being developed into an on-line course.


    The North Central Region Sustainable Agriculture Research and Education program strengthens rural communities, increases farmer profitability, and improves the environment by supporting research and education. This project supported these efforts by providing new production and marketing opportunities for diversified farms, improving the profitability of farm operations and increasing consumers desiring fresh, local, organically grown vegetables.

    How do you help thousands of consumers experience the opportunities and value of fresh, locally grown, organic vegetables and get to know the growers that produce them? You provide fresh, locally grown organic vegetables in the winter when they taste the best and you can get the most attention. Using unheated greenhouses, growers can profitably produce high value winter salad greens and vegetables that will provide market visibility and income at a unique time of year. Growers will also have opportunities to provide information about the true cost of long distance transportation of food, the value of supporting local farmers, and the need to consider personal health and wholeness.

    Most people know very little about their food, where it comes from, the nutritional value, and the methods used to produce it. One way to teach more about food is to have school children grow vegetable gardens. However, most students are not in school during the primary growing season. Most school teachers also have very little knowledge about gardening or agriculture. Despite that, there is usually a lot of enthusiasm for gardening. While most schools or teachers do not have the funding, commitment, or knowledge to operate a heated greenhouse, an unheated cold frame structure is affordable and very easy to construct and manage. A 30' x 48' high/tunnel would provide adequate space for a successful school gardening project for approximately a $5,000 investment. The key is providing detailed directions, the correct selection of crops, cultural information to successfully grow the crops, and an experienced support person.

    Clarification of terms. There are several possible terms to refer to unheated greenhouses used for season extension and winter vegetable production. “Hightunnels” is based on the earlier term “low tunnels” referring to single crop rows covered with plastic. A “high tunnel” is covered with one layer of polyethylene and may be 10 to 18 feet wide and just tall enough to walk inside. The term “hoophouse” is used for similar, but usually larger structures made with greenhouse metal frames, which are usually covered by two layers of inflated polyethylene. In some cases, the term greenhouse is used, although since there is no heat, the term passive solar greenhouse is more accurate. For this report, although hightunnels was used in the proposal, the term passive solar greenhouse (PSGH) will be used.

    Background. Eliot Coleman (2000, 1995) is recognized as an authority and primary commercial proponent of year round production. His primary method is based on moveable greenhouses. This method allows exposure of the soil to full sun and leaching rain which he considers necessary for soil health and best crop rotation. Partial year coverage with movable greenhouses is feasible for large scale production and can be applied a variety of ways. Other growers under production for shorter periods of time are growing in more permanent structures (Moore and Moore, 1999). A key to permanent structures is maintaining soil health through the use of compost, cover crops and other sources of organic matter. However, there currently are few specific, published recommendations regarding rates of compost or use of cover crops in small production areas.

    The published recommendations are based on success by growers in climate zone 5. Coleman (2000, 1995) reports that each layer of cover provides protection allowing the survival of plant species analogous to moving one climate zone south. For example, a single layer covering will provide conditions similar to zone 6 in our zone 5. A second layer of covering will provide comparable zone 7 conditions.

    Extensive lists of suitable cool season vegetable crops are available from Coleman (2000) and others (Colebrook, 1998; Head, 1989; Poisson and Poisson, 1994). Biernbaum (unpublished data) grew 30 leafy salad crops selected with input from growers and Johnny=s Selected Seeds in Albion, Maine. Salad Green crops included arugula, beet, chard, Chinese cabbage, claytonia, cress, endive, kale, several types of lettuce, mache, mibuna, minutina, mizuna, mustard, spinach, tatsoi, turnip, and vitamin green. The leafy salad greens typically have low cost seed, germinate quickly, and develop quickly with harvest possible in 25 to 60 days. Examples of other vegetable crops previously grown in the winter greenhouse include carrots, beets, Chinese cabbage, pac choi, green onions, leeks, celery and potatoes.

    A wider range of soil management options exists for higher value, intensively cultivated crops than for field crops. One way to quickly increase soil organic matter and nutrient levels is to apply compost (Coleman, 1995). However, specific recommendations of how much compost based on the nutrient content of the compost and the rate of availability are not available.
    Salad greens research at Michigan State University tested two fertility treatments; compost made on site or a 3-1-5 alfalfa based organic fertilizer (Bradford). Both of these treatments are reproducible and recommendations can be developed for growers with limited experience.

    Literature Cited:

    Byczynski, L. 2000. We=re hoophouse converts. Growing for Market Vol 9:11.

    Byczynski, L. (editor) 2003. The Hoophouse Handbook: Growing Produce and Flowers in Hoophouses and High Tunnels. Fairplain Publications Inc. 58 pages.

    Cohlmeyer, D. 2000. Cookstown Greens grows year round: Season extension and storage facilities keep restaurants supplied all year. Growing for Market Vol 9:11.

    Colebrook, B. 1998. Winter Gardening in the Maritime Northwest: Cool Season Crops for the Year-Round Gardener. 163 pgs.

    Coleman, E. 2000. Four Season Harvest: How to Harvest Fresh Organic Vegetables From Your Home Garden All Year Long. Second Edition (first edition in 1992). Chelsea Green Publishing Company, White River Junction, VT. 212 pgs.

    Coleman, E. 1998. The Winter Harvest Manual: Farming the Back Side of the Calendar. Four Seasons Farm, Harborside, ME. 57 pages.

    Coleman, E. 1995. The New Organic Grower: A Masters Manual of Tools and Techniques for the Home and Market Gardener. Chelsea Green Publishing Company, White River Junction, VT. 340 pgs.

    Ferrerase, M. 2005. It takes a village to raise a salad: The development of the Student Organic Farm and Community Supported Agriculture Program at Michigan State University. MS Thesis, Michigan State Univeristy, East Lansing, MI.

    Moore, S. and C. Moore. 1999. Inside a passive solar greenhouse, crops thrive both winter and summer. Growing for Market. 8(12):10-12.

    Poisson L. and G Poisson. 1994. Solar Gardening: Growing Vegetables year-round the American Intensive Way. Chelsea Green Publishing Co., White River Junction, VT. 267 pgs.

    Reardon, E. 2005. Salad lunches and radish dreams: Greenhouse gardening at Grayson Elementary School. MS Thesis, Michigan State University, East Lansing, MI

    Project objectives:

    The stated outcomes proposed were:

    1) One hightunnel (greenhouse) will be built at a farm and one at an elementary school and the farmer and teachers will be assisted with purchasing necessary equipment and seeds for producing crops. The farmer or teachers will explain their experiences to workshop participants.

    2) Farmers and school garden program coordinators will be provided the information necessary to purchase and construct a polyethylene film covered hightunnel (greenhouse) and organically produce winter greens and vegetables for local sales or school lunches. The primary method of information dissemination will be a two day workshop including a field trip, PowerPoint Presentations and a detailed manual.

    The secondary outcomes resulting from the project completion will be 1) a greater visibility of local, organically grown food, 2) an increased understanding of the need to support local farmers and locally produced food, and 3) an improved understanding of the soil food web and the importance of soil health.

    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.