Comparison of Coverings Over Permanent Raised Beds to Extend the Growing Season for Year Round Food Production

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2008: $6,000.00
Projected End Date: 12/31/2010
Grant Recipient: Prairie Birthday Farm
Region: North Central
State: Missouri
Project Coordinator:
Dr. Linda Hezel
Prairie Birthday Farm LLC

Annual Reports


  • Vegetables: beans, beets, onions


  • Crop Production: continuous cropping, no-till
  • Education and Training: demonstration, on-farm/ranch research
  • Energy: solar energy
  • Farm Business Management: budgets/cost and returns
  • Production Systems: organic agriculture
  • Sustainable Communities: local and regional food systems

    Proposal summary:

    Permanent raised beds will be covered with three materials in various combinations and temperatures (ambient and internal air as well as soil) measured from November through April. Three cold tolerant crops will be grown to determine which cover combinations provide the best growing conditions for year round food production for family consumption and local produce sales. PROBLEM/SOLUTION The problem: Though we eat 12 months a year, the food production season in Missouri and in much of the Midwest is about 7 months. Extension of the local food production season using replicable, sustainable, and solar energy resources is needed. Identification and evaluation of a covered, permanent raised bed crop production design is needed to fill a major gap in year-round local food availability. Importance: Extending the local food production season from November through April using replicable, sustainable, reusable, energy efficient permanent raised beds will increase farm profitability, support local food security, and empower many growers using small acreage, urban, and even school-based farms and community gardens to produce local, nutrient-dense food for personal consumption and sale. Producing local food from working landscapes, especially in quantity, requires best management practices that are feasible for many growers. A detailed description of the innovative plan to test sustainable agriculture solutions to the problem: This project will identify and evaluate 3 different covers and their combinations placed over permanent raised beds in order to determine which cover or combination of covers will successfully enable winter food production. A permanent raised bed (prb) is a growing space filled with compost that is constructed with rigid walls and stays in place permanently or for many seasons, in comparison with a raised bed being plowed down and reconstructed every year as with more conventional practices. For this project, the prb is constructed of 8x8x16”; 40-pound concrete block stacked two tall. Each 64-block bed is 4’ x 16’. The prbs are oriented east to west in an area approximately 50 x 100 feet. Raised Bed Construction/Cover — Eight, previously constructed permanent raised beds, filled with compost made on the Farm, will be outfitted for winter growing by: • Installing in the holes of the concrete blocks, along the long axis (east/west orientation) of the beds, two vertical pipes embedded in concrete approximately every four feet. • Pipe (two courses to hold covers above the soil) will be inserted into the vertical pipes in the concrete on each long axis and arched over the bed. • Thus, each bed will have one course of five arched pipes, approximately 3’ at the highest point of the arch. • A second course of five shorter arched pipes approximately 2.5’ at the highest point of the arch will be below each of the above pipes. • Remaining holes in the concrete blocks will be filled with compost to provide insulation and for solar heat storage. These become added growing space from April through October when the beds are uncovered. The beds will be outfitted with multiple combinations of row covers to examine which combinations are needed to trap and store solar heat to protect cold tolerant crops from killing frost. Row cover materials to be tested are polyethylene, copolymer resin, and spunbonded polypropylene. These materials were chosen because they are readily available, useable by one person, easily stored when not in use, and reusable over several years. Exterior covers will be held in place with wood posts laid along the long axis of the bed. Beds will be randomly assigned to the treatment covers. The eight prbs will be covered (treated) as follows: • No covers to serve as a control. • One course of six ml polyethylene on the upper most arched pipe. • Two courses of six ml polyethylene plastic suspended on arched pipes over the bed and thus separated by an air space. • One course of three ml copolymer resin suspended on the upper most arched pipes. • Two courses of three ml copolymer resin suspended on arched pipes over the bed and thus separated by an air space. • One course of six ml polyethylene suspended on the upper most arched pipes over the bed plus a layer of floating row cover (14 mil, 2 oz. per square yard). • One course of three ml copolymer resin suspended on the upper most arched pipes over the bed plus a layer of floating row cover. • One course of six ml polyethylene on the upper most arched pipe and one course of three ml copolymer resin suspended on lower arched pipes over the bed and thus separated by an air space. Temperature Control/Monitoring — The south walls of all beds will be covered in black plastic (removable in summer) to use the concrete block wall as a passive solar collector. Placed in the center, inside each bed will be two temperature probes. Soil probes will be placed at 4” depth, and air temperature will be measured six inches above the soil. Air temperature probes will be shielded to avoid false readings due to solar gain. All probes will be attached to a micro data collection station to measure, record, and graph on a personal home computer using a data shuttle, the internal minimum and maximum soil and air temperatures relative to the ambient air. Crop planting, growing and harvest logs will be matched to the various cover combinations and temperature measurements to identify optimal conditions in which to grow winter hardy crops in covered permanent raised beds. Beds will not be opened to make visual observations during extreme cold (below 30 degrees F), but observations will be made as ambient air temperatures permit. Manual ventilation will be provided to beds when high (90 degrees F) internal air temperatures dictate. Test Crops — Three crops (fava bean, Swiss chard, beets) will be planted in each bed to test their responses to the various growing conditions. These crops were chosen for cold hardiness, nutritional value, length of production, and salability. All will be seeded directly into the beds as fall plantings. All crops will be planted in all areas (sides, ends, and center) of the beds to ensure comparable growing conditions. Irrigation — Given that rain will not permeate the various treatment covers, a bucket-drip irrigation system will be installed so that beds are irrigated equally without exposing them to ambient air during cold, but above-freezing temperatures. Bucket drip irrigation was chosen for the following advantages: minimal investment, lasts several years, needed water is applied directly to the soil, can be installed and used by one person, adaptable to small farms and growing spaces, kits and instructions are readily available. PREVIOUS RESEARCH Primary research: At Prairie Birthday Farm, a mini-pilot project was conducted in three, existing permanent raised beds the winter of 2006-2007 and successfully “over-wintered” several fall-planted, cold tolerant crops to lush growth without the use of external heat sources. Not only did the beds produce ample greens for a family of four from November through April, but also as early as April, sufficient quantity and quality of produce was available for sale. A rudimentary, and thus unreliable, minimum/maximum thermometer was used to get a general idea of how temperatures were fluctuating under certain weather conditions inside the covered beds. A more deliberate, reliable measurement of growing conditions with certain cover combinations will produce more predictable results for which other growers can use to expand their operation for year round food production. Secondary research: No previous research was found in periodicals or texts that measured temperatures under various materials, using particular cold tolerant crops, and specific design characteristics. Researching and documenting these details will provide usable information to empower more growers to make use of the many advantages of prbs on a 12-month basis without wasting resources on untested design and materials. The growing consensus acknowledging the advantages of permanent raised bed food production supports the need for the results from this project. The Noble Foundation Horticulture Center ( and others, note many proven advantages to permanent raised bed growing (higher yields, extended season, and lack of soil compaction). Further, the research indicates that permanent raised bed growing increases the soil quality (Plant and Soil, V 291, No 1-2 / February, 2007) through reduced tillage, rebuilt soil structure, and increased soil organic matter ( Comprehensive benefits of permanent raised bed growing which support the need for this project include the ability to: • Retain the roots of previous crops • Protect soil organic matter/biota from the degradation of weather conditions • Amend soil between and for individual crops • Improve drainage and early access during wet springs • Promote earlier growth as soil warms earlier • Use high-density plantings (shade to soil, decreases evaporation, impedes weed germination, and keeps roots cooler) • Better protect plants from high-wind events with the prb low profile • Provide water only to the beds/crops and not to the pathways • Easily protect plants with pest-deterring covers (bird netting, floating row covers) • Create forages for micro-livestock (poultry, rabbits) • Accommodate physically challenged growers who require elevated work surfaces • Install prbs in many growing spaces without a building permit • Use agroforestry principles to grow shade-dependent food plants by alley cropping with prbs between trees OUTREACH To better promote the results of this project to farmers/growers, outreach will include: • A poster presentation at the Kansas City Food Circle’s 12th annual Farmers Forum for growers and consumers who meet to buy/sell produce. Attendance in 2008: 1,656. • Submission of a proposal to the Great Plains Vegetable Growers Conference. This annual event attracts vegetable, cut flower, and other growers from Kansas, Missouri, Iowa, Nebraska and South Dakota. It includes educational programs featuring conventional and organic production and marketing of crops. • Submission of a proposal to conduct a Growing Growers workshop and tour at Prairie Birthday Farm. Growing Growers is a program to train farmers in local food production. The goal is to increase the effectiveness of small farms that grow food organically and/or sustainably in the Kansas City metro area. The Training Program is a collaborative effort between Kansas State University Extension, University of Missouri Extension, the Kansas City Food Circle, the Kansas Rural Center, and local farmers. • Submit an article to Urban Grown, the e-newsletter of the Kansas City Center for Urban Agriculture, a non-profit organization established to promote community-based, small-scale, entrepreneurial farming in urban Kansas City. • Create a downloadable fact sheet on the project to post on the Prairie Birthday Farm Web site with cross-linking information to regional farmer/grower sites. EVALUATION Environmental impacts: Each bed’s treatment [cover(s)], temperatures, and crop results (survival, growth, weight) will be documented in an effort to determine if any combination of treatments, crops, and temperatures is more successful for food production from November through April. Soil and air temperatures will be measured, graphed, and compared among treatment conditions. Treatment applications and crop results will be photographed for use in outreach presentations and documents. Economic impacts: Costs for previously constructed beds plus specific project treatment material costs will be compared to salable crop production to examine feasibility and profitability of this method for food production. Crops will be harvested at salable maturity, weighed, and income from the crops calculated using area retail prices. These calculations are necessary to determine when a profit/return from the investment might be expected. Social impacts: A simple survey will be conducted at the appropriate outreach events to learn the likelihood that attendees could incorporate the information into an agriculture venture and what potential barriers to implementation attendees identify. The experience of conducting research and applying results will be incorporated into future Growing Grower’s apprentices’ experience. The research experience and results will be mined for needed adjustments to covered, permanent raised-bed growing methods to improve crop production and reduce costs to the grower. Possible future research topics will be identified to add long-term benefits to this project. A successful, year-round growing model will help build economic resilience through re-localization of food production. DESCRIPTION Prairie Birthday Farm is a 15-acre, biodiverse, sustainable farm and land stewardship effort, which strives to mimic nature in design and diversity of species. It includes heirloom and wild fruit and nut trees and bushes; tall grass prairie (as habitat for beneficial insects, amphibians, and birds), honeybees; permanent raised-bed heirloom vegetable gardens; a culinary herb and edible flower garden; as well as bramble/vine gardens. Pastured chickens and ducks as well as rotation-paddock pastures for two horses provide for on-farm compost production. Produce has been sold to area residents from the Farm and to nine restaurants for the past three years. A total of seventeen raised beds (4 x 16 feet) are dispersed around the farm to take advantage of growing conditions, deter insect infestations, minimize rampant disease events, and mimic natural diversity as much as possible. Farm-related research includes: a 2002, Missouri Sustainable Agricultural Demonstration Award for research on the development of native grasses and forbs as orchard floor management and cooperating with Dr. Robert Kremer, USDA-ARS-Cropping Systems and Water Quality Unit, University of Missouri, Columbia, in the 5th year of on-going soil research on the effects of organic management at Prairie Birthday Farm on the biochemical characteristics of soil (“soil quality or soil health indicators”) as an assessment of soil health. Results have been presented at state and national meetings and published in state and national journals. [Editor's note: To see the article, Soil quality improvement under an ecologically based farming system in northwest Missouri by Robert J. Kremer and Linda F. Hezel that was published in "Renewable Agriculture and Food Systems" / "FirstView" Article / January 2006, pp 1-10 and published online: 16, May 2012, see the attached PDF file.] Outreach and education experience includes being a host farmer since 2004 for six aspiring farmers from the Growing Growers Program. Post-graduate education, a master’s degree in nursing and Ph.D. in education, provides a unique perspective on the health of the food produced and its impact on the health of consumers and the environment. It also enables this farmer to present findings in multiple educational venues using audience-appropriate teaching methods. As a farmer, a nurse, and an educator, I am committed to teaching others about producing nutrient-dense, accessible and affordable fabulous food as one means to good health.

    Project objectives from proposal:

    This project will identify and evaluate 3 different covers and their combinations placed over permanent raised beds in order to determine which cover or combination of covers will successfully enable winter food production.

    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.