Winter Spinach High Tunnel Project |
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Introduction
The Lake Superior region of Wisconsin is home to at least 70 high tunnel greenhouses being used by commercial and home growers primarily for summer production of vegetables. In cooperation with area schools and local growers, UW-Extension has launched a research program to investigate use of the high tunnels to produce hardy salad greens during the winter months.
With funding from the WI Specialty Crop Block Grant program, UW-Extension will be using three area high tunnels over the next two years to research winter spinach production with the goal of publishing a how-to manual for growers in the region. The hope is the 70+ high tunnels can be put to work in the winter to produce high-value greens for local markets.
With funding from the WI Specialty Crop Block Grant program, UW-Extension will be using three area high tunnels over the next two years to research winter spinach production with the goal of publishing a how-to manual for growers in the region. The hope is the 70+ high tunnels can be put to work in the winter to produce high-value greens for local markets.
| research_bulletin_37_high_tunnel_survey_results.pdf |
Washburn High School high tunnel emitting a pink glow due to supplemental LED lights. December 2016
2016/2017 Research Trials
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The trials have two main objectives:
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For more detailed information about the ongoing trials see the Bulletin below. For questions or comments contact:
Jason Fischbach at jason.fischbach@ces.uwex.edu
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Trial Locations and High Tunnels
The trials are being conducted in each of three area high tunnels. The high tunnel at the Washburn High School is a 22’x 48’ Northpoint from Rimol Greenhouse Systems. The tunnel has two layers of 6 mil IR greenhouse film with an inflation blower. Sidewalls are a single layer of 6 mil film. Endwalls are a single layer of Solarside poly. The high tunnel at the Drummond High School is identical to the Washburn tunnel. The third high tunnel is located at a farm near Mason, WI. It is a 30’ x 96’ gothic style tunnel from Harnois with a single layer of 6 mil film. The trials are using five beds in each high tunnel. At both Washburn and Drummond the beds are raised with 2”x 6” boards. At the high tunnel near Mason, the beds are at ground level. The two outer beds in each tunnel are used for the variety trials and the three interior beds are used for the heat and light trials.
Spinach Variety Trial
The trial is comparing the performance of six varieties of spinach chosen based on performance in similar trials in New Hampshire and Utah: ‘Corvair’, ‘Emporer’, ‘Banjo’, ‘Renegade’, ‘Space’, ‘Responder’. The trial is arranged as a complete block split-plot design with four replications. There are two whole plot treatments: A) Direct seeded on September 15 and, B) Plugs started on September 15 and transplanted into the beds on October 6. The split-plot treatments are the six spinach varieties. Each split plot has five rows with 7-9 plants per row depending on the location. The row spacing is 4” and the in-row spacing is 4”. When temperatures in the high tunnel drop below 45F, the raised beds are covered with frost blanket draped over 9ga wire hoops to create a low tunnel within the high tunnel.
Heat and Light Trial
The heat and light trial is investigating the yield and performance of ‘Corvair’ in response to different heat and light combinations. Within each high tunnel the three interior beds are covered with a low tunnel made from wood and a 1.5oz medium weight frost blanket. Low tunnel 1 receives no additional heat. Low tunnel 2 is heated to maintain a minimum temperature of 32F. Low tunnel 3 is heated to maintain a minimum temperature of 45F. Heat is added with a thermostatically-controlled 5000w forced air space heater via a poly-tube that runs the length of the low tunnel. Half of each low tunnel receives 12 hours of LED light (7AM to 7PM) from fixtures suspended from the top of the low tunnel (Philips Gen2 Deep Red/Blue 150). Within each light-temperature combination there are three replications each of four different plantings of ‘Corvair’: direct seeded on September 15, direct seeded on September 30, plug trays started on September 15 and transplanted into the beds in early-October, plug trays started on October 1 and transplanted into the beds in late-October. Each plot is 32” x 20” with five rows of spinach planted in a 4” x 4” grid.
Data Collection
A plot is harvested when the canopy coverage of that plot has reached 90%. Due to the difference in treatments applied to specific plots and influences from temperature and daylight not all plots are being harvested at the same rate. Harvest is done by hand by pinching off all expanded leaves with a visible petiole. The plots will be harvested into the spring until the plants begin to bolt. Total fresh weight yield will be determined and compared across treatments.
The trials are being conducted in each of three area high tunnels. The high tunnel at the Washburn High School is a 22’x 48’ Northpoint from Rimol Greenhouse Systems. The tunnel has two layers of 6 mil IR greenhouse film with an inflation blower. Sidewalls are a single layer of 6 mil film. Endwalls are a single layer of Solarside poly. The high tunnel at the Drummond High School is identical to the Washburn tunnel. The third high tunnel is located at a farm near Mason, WI. It is a 30’ x 96’ gothic style tunnel from Harnois with a single layer of 6 mil film. The trials are using five beds in each high tunnel. At both Washburn and Drummond the beds are raised with 2”x 6” boards. At the high tunnel near Mason, the beds are at ground level. The two outer beds in each tunnel are used for the variety trials and the three interior beds are used for the heat and light trials.
Spinach Variety Trial
The trial is comparing the performance of six varieties of spinach chosen based on performance in similar trials in New Hampshire and Utah: ‘Corvair’, ‘Emporer’, ‘Banjo’, ‘Renegade’, ‘Space’, ‘Responder’. The trial is arranged as a complete block split-plot design with four replications. There are two whole plot treatments: A) Direct seeded on September 15 and, B) Plugs started on September 15 and transplanted into the beds on October 6. The split-plot treatments are the six spinach varieties. Each split plot has five rows with 7-9 plants per row depending on the location. The row spacing is 4” and the in-row spacing is 4”. When temperatures in the high tunnel drop below 45F, the raised beds are covered with frost blanket draped over 9ga wire hoops to create a low tunnel within the high tunnel.
Heat and Light Trial
The heat and light trial is investigating the yield and performance of ‘Corvair’ in response to different heat and light combinations. Within each high tunnel the three interior beds are covered with a low tunnel made from wood and a 1.5oz medium weight frost blanket. Low tunnel 1 receives no additional heat. Low tunnel 2 is heated to maintain a minimum temperature of 32F. Low tunnel 3 is heated to maintain a minimum temperature of 45F. Heat is added with a thermostatically-controlled 5000w forced air space heater via a poly-tube that runs the length of the low tunnel. Half of each low tunnel receives 12 hours of LED light (7AM to 7PM) from fixtures suspended from the top of the low tunnel (Philips Gen2 Deep Red/Blue 150). Within each light-temperature combination there are three replications each of four different plantings of ‘Corvair’: direct seeded on September 15, direct seeded on September 30, plug trays started on September 15 and transplanted into the beds in early-October, plug trays started on October 1 and transplanted into the beds in late-October. Each plot is 32” x 20” with five rows of spinach planted in a 4” x 4” grid.
Data Collection
A plot is harvested when the canopy coverage of that plot has reached 90%. Due to the difference in treatments applied to specific plots and influences from temperature and daylight not all plots are being harvested at the same rate. Harvest is done by hand by pinching off all expanded leaves with a visible petiole. The plots will be harvested into the spring until the plants begin to bolt. Total fresh weight yield will be determined and compared across treatments.
