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.
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
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.
This project was primarily an education project with the research component funded separately and occurring earlier. There were five key events:
1) Development of the training materials; 2) construction of the greenhouse and crop production at Giving Tree Farm; 3) presentation of the 2 day workshop for farmers; 4) construction of the greenhouse and crop production at Gunnisonville School; and 5) presentation of the 1 day workshop for school garden organizers. Information about additional workshops is also presented.
Time Line of Key Events.
July 2002: Funding started.
Fall 2002: Separately funded organic baby salad greens project; second year of research
Building 3 greenhouses for W.K. Kellogg funded Student Organic Farm and 48 week CSA
Sum/Fall 2003: Construction of greenhouse at Giving Tree Farm
March 2004: Two day workshop at MSU for 32 participants
Sum/Fall 2004: Construction of greenhouse at Gunnisonville School
Fall04/Spring05: Graduate student organized greenhouse gardening project with the school
March, 2005: One day workshop for school garden projects at Gunnisonville School
Feb, 2005: One day workshop for 60 growers at the MOSES Organic University in LaCross, Wisconsin as part of the Upper Midwest Organic Farming Conference. Presented together with Bill Warner and Judy Hagerman, Snug Haven Farm (WI).
1. Development of Training Materials. Outlines of the training material were partially based on farmer presented workshops and brief presentations to visitors to the MSU research site. Each additional presentation of material allowed development of more detail and graphics to address questions raised. Initially Power-Point presentation allowed compiling the key topics and photographs which could be provided to workshop participants as printed handouts. Currently there are 400 Power-point screens used in the two day presentation with condensed versions available for 45 or 90 minute presentations. The presentation includes pictures from farms using PSGHs (Eliot Coleman, Steve Moore, others) and graphics of environmental monitoring (temperature), soil fertility, crop scheduling, and yield data. A text version was then gradually developed, with sequential revisions going from 5 to 10 to over 20 single spaced pages of information. Development of a list of commonly asked or questions that should be asked followed and currently includes six pages of “study guide” questions. The next stage of formal course development is now in progress and includes stated learning objectives for each section, assignments to be completed and submitted for assessment, and a final exam based on the study guide questions. The Power-point presentations are forming the basis for screen content of the on-line course.
2. Giving Tree Farm. Giving Tree Farm (GTF) was selected as the farm cooperator and the site for construction of the greenhouse. Susan Houghton, farmer at the site, had organic and greenhouse production experience and was developing CSA, restaurant, and wholesale marketing. A limiting factor was greenhouse space. There was also an existing partnership with MSU related to the research and student training. GTF is located approximately 15 miles from MSU so could be included in field trips during the workshops.
It is important to note that GTF is a 501c3 and farming only provides part of the income. GTF is also a site for activities and training for adults with certain types of injuries or conditions. The PSGHs provide an extended season for client visitations.
At least five greenhouse manufactures were considered and provided price quotes. The FarmTek gothic shaped coldframe (Solarstar Greenhouse) was selected based on the lower price and because other farmers were using this structure. The project paid for one 30’x96’ greenhouse and GTF paid for a second. One of the greenhouses was built as the standard frame with a 12’ peak height and one was built with 3’ extended ground posts which resulted in a 15’ peak height and side walls tall enough to allow walking right along the walls. We wanted to test placing walkways on the perimeter where the soil is coldest and perhaps less productive.
The greenhouses were built over a period of weeks, as work time and labor were available. In other words, rather than completing construction by mid-September, it was not completed until the end of October. We did not know as much about greenhouse construction and did not have adequate labor to go any faster. With our current knowledge, we believe a more rapid, “barn-raising” type event would be preferred although we have not had the opportunity to actually do so.
The first crops (spinach) were seeded the first week of November, 2003 and ended up providing several hundred dollars of sales during March and April 2004. Equipment for Giving Tree Farm was purchased during the fall 2003 and spring 2004 and included hand tools, a seeder, and irrigation equipment.
3. Workshop for Farmers. The first workshop funded by the project was scheduled for two days in early March during the MSU College of Agriculture and Natural Resources Week. This is normally the time of the Michigan Organic Agriculture Conference but there was no conference in 2004. The workshop was designed for 32 participants which was the right number for the classroom facility and the field trip. Grant funds covered the cost of the bus for the field trip transportation, handouts of all Power Point presentations and additional articles, two booklets (“The Hoophouse Handbook” (Byczynski, 2003) and “The Winter Harvest Manual” (Coleman, 1998)) and the guest speaker. A registration fee covered the costs of registration and three catered meals. Steve Moore, a long time proponent and practitioner of using passive solar greenhouses for vegetable production was the guest speaker, a valuable resource and provided information about the operation of his farm in Pennsylvania.
4. Gunnisonville School. During the spring of 2004, the ground work occurred to allow construction of a PSGH at Gunnisonville School. The school had been and continued to be part of an MSU project to study the impact of school gardening on the school and students. The fact that the school was within 5 miles of Giving Tree Farm was also helpful. There were some issues related to school district policy, identifying the best site, and meeting fire and safety codes. We also made a presentation to the Lansing School Board about the project which was a long term benefit due to the relationship building that occurred. We considered availability of water for irrigation and the orientation of the greenhouse for light and cooling. The site was mulched during the spring with a layer of leaves, straw and llama manure compost to help with breakdown of the existing sod. The site was rototilled twice during June and July. The PSGH was ordered for late July delivery.
PSGH construction at Gunnisonville began during August. The initial frame construction was completed by teachers, staff and students assisted by new farmers at Giving Tree Farm and The MSU-SOF that wanted to know about greenhouse construction. An important change in the program occurred when an MSU graduate student working with the PI on the MSU-SOF project expressed the desire to do her MS thesis project at the school. Emily Reardon took responsibility for coordinating activities in the greenhouse and student experiences related to planting, maintaining and harvesting. The complete story is available in her thesis (Reardon, 2005). Bed construction and preparation for planting occurred in early September. Endwall construction also occurred during September and the plastic film cover was installed by the fifth grade students in early October. Necessary tools and equipment, including inside frost covers, irrigation equipment and hoses to reach the greenhouse from the school were purchased with grant funds. Remaining funds were used in the spring of 2005 to build raised beds and landscape fabric for mulched walkways in the outdoor garden.
While our first year was very successful, our second year was put on hold due to the announcement that the water as the school was above acceptable levels for arsenic. Indications are that the school will be closed for a variety of reasons. If so, we will relocate the greenhouse to another school.
5. Workshop for School Gardening. Advertising and recruitment for the school garden workshop were started more than a year in advance based on experience with the first workshop. As registration started, we were able to quickly get the desired 32 participants and the final participant count was 41. We decided to have the workshop as only one day and to hold it at the school on a day when the students were not in session. Many of the workshop participants were not teachers but support personnel or parents interested in school gardening. A $30 registration fee covered the cost of handling registration and a catered organic lunch.
The workshop content was planned based on the observation that many of the participants were as interested in starting school gardens as they were in using a greenhouse. After touring the greenhouse garden to start the day, we spent much of the morning sessions with presentations about school gardens in general, how gardening can support the existing required curriculum, and how teachers need help with any gardening activities. Dr. Laurie Thorp, who had been heavily involved in the Gunnisonville garden was able to share extensive experience (cite book – Thorp, 2006). Emily Reardon presented on how the teachers and students were involved in construction of the greenhouse and bed preparation and about the various activities that she scheduled and organized including individual classroom experiences and the all school salad lunches.
The last part of the morning and all afternoon were spent reviewing information about greenhouses, available options, construction methods, management methods, and growing methods. The detail of the content was reduced from what was presented to farmers. Based on information collected during registration, our pre and post workshop surveys, and participants self introductions, it was clear that a one day introduction to the concepts was more appropriate than a detailed how to of methods.
6. Additional Workshops. Several additional invited workshops or presentations not funded by the grant were made using the materials developed. Approximately 125 participants at a New York one day conference hosted by Eliot Coleman heard specific information about light and temperature management in the passive solar greenhouse. One participant commented that the information on light was worth the $800 travel expenses to travel to the conference from out of state. The Midwest Organic and Sustainable Education Services (MOSES) also used much of the information for a one-day class attended by 60 participants. The class size was increased from the original 40 and more participants were available. As in previous workshops where farmers were involved in co-presenting, Bill Warner and Judy Hagerman from Snug Haven Farm in Wisconsin shared their 10+ years of experience. The combination of the farmer and university experience was frequently mentioned as a plus in post-workshop surveys.
Two additional two day workshops were presented in cooperation with the Farmers Research Cooperative and the Michigan Food and Farming Systems minority and limited resource farmer training programs supported by the USDA Risk Management Agency.
The stated objectives of the proposal were completed as outlined. PSGHs were built at Giving Tree Farm and Gunnisonville School, used successfully, and workshops were given (and attended) to transfer the information. While only two workshops were proposed, many more were presented. The key workshops are summarized in the following table. While 75 participants attended the grant sponsored workshops, 400 attended the listed workshops, with several other 45 or 90 minute presentations not listed.
Educational Materials. A complete set of the workshop and notebook materials will be provided to NCSARE. The current materials are presented in seven parts or units and there is a total of 400 slides or screens.
Part 1. Background and Marketing (54 screens)
Part 2. Site and Soil (54 screens)
Part 3. Structures and Designs (66 screens)
Part 4. The Building Process (28 screens)
Part 5. Environment: Light, Temperature, Fertility and Water (72 screens)
Part 6. Crops and Scheduling (78 screens)
Part 7. Harvesting, Pests, Cost Comparisons (46 screens)
There are also two PowerPoint presentations suited for a 45 minute or 90 minute time period.
A goal in developing the material was to provide experience and research based specifics and details but not to make the process complicated. The overall summary for winter crop production in unheated PSGHs involves four key steps. Step 1 is to plant the right crops that are tolerant of freezing, for example spinach, chard, and many other leafy or heading greens. Step 2 is to plant them at the right time, in September and October before the days become too short and cold. Step 3 is to use a majority of crops that can be harvested multiple times, such as baby leaf salad greens or leafy greens such as spinach, chard, kale, vitamin green, komatsuna, etc. Step 4 is to use the right protection and understand how the greenhouse, internal row covers and condensation act like clouds to trap long wave radiant energy from the soil in the greenhouse. The right crops, at the right time, using multiple harvests and the right protection.
Giving Tree Farm. Susan Houghton and GTF had multiple marketing strategies. Restaurant sales were likely the highest priority and benefited the most from the PSGHs. Baby leaf salad greens, spinach, other leafy greens, root crops, herbs and edible flowers were the major items. What started as one restaurant customer is currently 4 or 5 and sales grew from approximately $5,000 to $10,000 to $20,000 per year over the course of the project and have continued to grow. There are other marketing opportunities that cannot be met – ie production is the limiting factor. Production was successful enough that two additional 30’x96’ greenhouses were purchased (with grant funds provided to expand the community service component of GTF) and constructed during the summer of 2004.
It is fair to estimate that over 200 visitors came to GTF to see the PSGHs and methods being used. Susan Houghton has given generously of her time and knowledge. A dozen or more students and employees have worked with Sue and taken her teachings on to other farms or positions.
Farmer Workshops. We learned that generally less than 10% of the workshop participants already had PSGHs. When asked, about half of the workshop participants characterized themselves as trying to learn enough to decide if a PSGH was good for their farm and half already thought it was good for them and they wanted to know the specifics of how to proceed. The exception to this general finding was the MOSES Organic University workshop where most of the 60 participants had a PSGH or where ready to build and they wanted specifics.
It is important to assess how much the participants want to know about building a greenhouse verses growing the plants. Once the overview and principles are demonstrated, most first time participants or those new to the idea are first concerned about what type of greenhouse, what options to select, how much will it cost, and how to build it. While PSGH construction at first seems challenging, after building one the consensus is that it is not that hard if the ground posts are properly installed. There is often a tendency to want to make your own structure from inexpensive materials, but the consensus of those who have done both tends toward spending the money to buy a manufactured structure. Material costs can be reduced on roll-ups and endwalls by using local materials compared to those supplied by greenhouse manufactures, but the time requirement of assembling the materials can prevent any real savings. While we tend to recommend a bigger and better structure because we know the production potential, we possibly should be recommending smaller to moderate size structures (20’ wide vs 30’wide) for farmers just getting started.
Once past the concerns about greenhouse selection and construction, the attention is on crop selection and scheduling. While exact schedules are not possible due to weather fluctuations, what farmers are seeking is recommendations or examples of timing requirements. There also is interest in knowing what types of income are possible. There seems to be minimal questions or concerns about how to manage soil fertility with organic methods. Our recommendation is to realize that with proper irrigation, nitrogen can be conserved due to lack of rainfall and leaching. It is also evident that added soil organic matter seems to disappear quickly, likely due to elevated soil temperatures and therefore active soil biology.
School Garden Workshop. While the impact of PSGHs on farm production and income can be significant, the impact on school gardening is dramatic. We demonstrated that students beginning school in early September can plant greenhouse gardens and harvest vegetables right up to the winter break. If the PSGH is not maintained over the break and through January, planting can resume in February with harvesting continuing to the end of the school year. The story of the Gunnisonville Greenhouse, with the named changed to Grayson for anonymity, has been written as part of a MS thesis project and will be available for distribution (Reardon, 2005).
While we only have one year experience with elementary students at Gunnisonville School, we have three years experience at MSU with undergraduate students. Year-round farming in PSGH is the basis for a one year organic farming certificate program being developed. The principles can be applied at elementary, middle, high school FFA or science programs, community colleges and universities. The city of Lansing community gardening project was inspired by GTF and the MSU-SOF and is building a heated greenhouse during the summer of 2006 to use for community food gardening.
Our presentations and experiences contributed to the growing interest in low cost protected cultivation and season extension that is primarily being driven by farmer experience. We do not have a formal assessment tool but indications are that at least 12 farmers have built or are planning to add greenhouses. The limitations are often lack of funds to purchase the greenhouse and or time for something new, and not a lack of information. We know of two school garden greenhouses that have been constructed by workshop participants and others who are seeking funding. The limitation appears to be support for school gardening in general.
The training materials developed for this project, will also be used and thoroughly tested during the fall of 2006 to prepare nine farmers to build and use a grant funded greenhouse to be built on their farm. The purpose of this research by Dr. David Conner of the C.S. Mott Sustainable Food Systems Group at MSU is to develop much needed economic data of the impact of adding a PSGH to a farm that is already selling at a farmers market. Three farms, each selling at the same market in one of three areas of Michigan (east, west, north) are involved in the study so the impact of season extension on the market will also be considered. As part of this project, a half time year-round production coordinator will be employed to help the farmers with construction and production, making use or the training materials. We are seeking additional funding to make the position full time and possibly have the person manage the on-line course being developed.
Other hightunnel/PSGH research has been completed or is planned at several other universities including Purdue, Ohio State, Illinois, Cornell, Penn State. Some of the more specific management questions about how to optimize the environment will be addressed.
The results have been applied for three years to operate a 48 week CSA program at the MSU Student Organic Farm. Income with 10,000 sq ft of greenhouses and six acres of field production is currently at $75,000/year for a 55 membership CSA. We are currently developing a one year organic farming certificate program where students will be involved in running the farm. (www.msuorganicfarm.com)
The workshop materials are now being developed into an on-line course that will be available through MSU as either a for-credit or not for credit offering. The on-line format has the potential to reach a much wider audience at a reasonable cost and when they have the necessary time.
A significant question addressed in the workshop materials but still requiring more detail is an evaluation of the cost of the greenhouse verses the income return of crops or return to students. Additional PSGH’s were built at GTF, but there are additional sources of income at the farm including grants. While GTF was perfect for some aspects of the project, an economic analysis appropriate for most farms is not possible. Clearly the more extensive economic research in progress, partially as a result of this project, is much needed.
Over the past four years the cost of the steel and plastic greenhouse components has increased significantly. Construction cost estimates have risen from $1.50 to $2.00 per square foot to $2.50 to $3.00 per square foot (50 to 70% increase). Over the same time the interest in organic and local food has also increased. Using MSU production schedules and yield data, gross income of $5.00 per square foot ($0.10/ sqft wk) of bed space per year are reasonable with $10.00 or more possible. For example, baby leaf salad greens at one pound per six square feet of bed space and sold at $6.00 per pound can generate $1.00 / sq ft in 3 to 4 weeks in warm weather and 6 to 10 weeks in cool weather, with recutting time much shorter. Reliable net income data is still lacking.
While PSGH crop production is perceived as being fairly common on small scale farms in the Northeastern United States, it likely is best classified as a developing technology in the Midwest. Season extension related to warm season vegetables (tomato, pepper, eggplant) is more common than winter production and harvesting of cool season vegetables. Based on tours of the MSU-SOF given during December, January and February, many people who see the greenhouses full of crops likely still leave not believing what they just saw. It clearly takes time for people to get used to the idea of “annual” crops growing through winter.
We have reached at least 400 workshop participants in the last 4 years, and hundreds more through tours or presentations about the MSU-SOF year-round CSA. The recommendation to farmers continues to be to start small and learn the process. Minimize capital investment to insure profitability. However, it is likely that experience will show that the capital investment is justified. The MSU study being initiated in 2006 will result in nine more on farm greenhouses in Michigan, it addition to at least 10 others built by workshop participants.
Educational & Outreach Activities
A series of four articles about the MOSES Organic University workshop written by an MSU student and workshop participant was published in NewFarm (www.newfarm.org). The notebook materials and a 20 page summary article are used regularly at workshops. The on-line course will be a key tool for continued distribution of the material. Our goal is to have 100 farmers complete the on-line course over the next year and to make it available to college students around the country for college credit and a grade. Two MS thesis were completed in Fall, 2005 (Ferrerase, 2005; Reardon, 2005) and will be made available on-line as PDF files.
Areas needing additional study
There are finer points of winter greenhouse management that were identified but were beyond the scope of this project. A key factor is that methods of greenhouse construction and management that increase insulation (reduce heat loss, like more layers of covering) generally also reduce sunlight, which is determining plant growth and soil/air temperature. How coverings and moisture on the coverings influence light, growth and heat retention can be better quantified. Developing more specific planting schedules and recommendations would also benefit farmers.
How the educational materials are presented can also be improved. In the current phase of development, we are including specific learning objectives, assignments, and study guide questions to improve the teaching and learning. Our future educational materials will start with more effort put into defining the learning objectives up front.
It is surprising how long it has taken to get a significant number of Michigan and Midwest farmers to buy into the idea of PSGHs for winter production. Part of the issue is the need to identify the difference between hightunnels for season extension of warm season vegetables and a more comprehensive system for winter harvesting of cool season vegetables. It is possible that the delay in adoption of this “technology” is partially because of the need to change perceptions about the biology of annual plant survival in the winter.
Another less considered but very real factor is the psychological and physical impact of farmers not having a deserved and needed winter break. That leads one to think about multifarm cooperatives and the potential for summer farmers and winter farmers. At the MSU SOF, we begin planting for the fall and winter greenhouse crops during July and August, which is also a busy time for harvesting and marketing. While our CSA requires significant personal time with the members over the year, the actual distribution time during the summer is much less than other forms of marketing. We also have staff and students that work hard to keep up with all the activity necessary for year-round farming.