- Vegetables: greens (leafy), greens (lettuces)
- Crop Production: high tunnels or hoop houses
In the North Central region winter production of vegetables in high and low tunnels contributes to sustainable agriculture by improving financial viability of farms and strengthening local food systems. One of the challenges of this relatively new production system is timing planting of crops to meet market demands and make good use of the space in the high tunnel. To address this problem this project was established to collect environmental information and cropping information from three established farms and use it to develop a scheduling tool and recommendations that would help farmers improve the match between when crops are ready for harvest and customers want to buy the crop.
In partnership with three Indiana farms the project installed dataloggers and sensors in high and low tunnels to measure solar radiation, photosynthetically active radiation, and air and soil temperatures, and to collect information on crop planting and harvest dates, and some yield information, during fall to spring growing seasons in 2015-2016 and 2016-2017.
The environmental data illustrated clearly the influence of solar radiation on temperatures in a high tunnel even on very cold days, how row covers affect light available to plants and temperature, and how using supplemental heat to maintain the minimum temperature above about 28°F, or to increase average daily temperature, leads to faster accumulation of growing degree days in the coldest months. Initial models suggest that if solar radiation and outdoor air temperature are known, average daily temperature inside a single or double-poly covered high tunnel can be predicted, and with that, a reasonable approximation of growing degree day accumulation inside the structure.
Planting and harvest records showed that earlier plantings in the fall generally had shorter times to first harvest. If planting was delayed enough in the fall, time to harvest lengthened significantly so that harvest did not occur until early the following spring. The date beyond which a planting wouldn't be ready until the next spring varied among crops and between structures, but generally was in mid-October to mid-November.
Educational resources were developed in two key areas: managing the environment in high tunnels for cool season production, and scheduling crops for cool season production. Resources included posters about the project, slide presentations at a variety of programs, a webinar, and a manuscript for an Extension bulletin. A short video and a second Extension bulletin are still under development.
As a result of the project farmers attending outreach events have learned about managing the environment and planting schedules for cool season crops in high tunnels. Farmers directly involved with the project have adopted new methods of using row covers, improved recordkeeping, reinforced awareness of the value of experimentation on the farm and have constructed new growing structures that incorporate more automation for managing the environment and heating systems.
The first objective was to compile and summarize information from partner farmers about their planting and harvest schedules. This provided the basis for identifying what crops to keep track of in the first year of the project. The second objective was to document planting and harvest dates, yield, and environmental conditions for selected cool season crops in unheated and minimally heated high tunnels and low tunnels. This was done in 2015-2016 and 2016-2017; with emphasis mainly on planting and harvest dates in 2016-2017. An additional objective in 2016-2017 was to compare the use of row cover supported on hoops, row cover used like a blanket, and no row cover. Once the data were collected the next objective was to create and deliver educational resources to help growers better manage the environment in high tunnels, and improve their planting schedule for winter crops in high tunnels.