Expanding Warm Season High Tunnel Production Using Solar-Powered Ventilation

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2016: $7,330.00
Projected End Date: 01/30/2018
Grant Recipient: The Farm at Kraut Run, LLC.
Region: North Central
State: Missouri
Project Coordinator:
Ryan Smith
The Farm at Kraut Run, LLC.


  • Vegetables: beans, beets, broccoli, cabbages, carrots, cauliflower, cucurbits, greens (leafy), peas (culinary), radishes (culinary), tomatoes, turnips, brussel sprouts


  • Crop Production: continuous cropping, crop rotation, intercropping, multiple cropping
  • Energy: energy conservation/efficiency, solar energy
  • Production Systems: general crop production
  • Sustainable Communities: sustainability measures

    Proposal summary:


    The Farm at Kraut Run received a high tunnel grant through the USDA NRCS program in July of 2013. We have been producing crops inside the high tunnel year round since it was constructed. Vegetable production inside the high tunnel during late spring and summer has been a struggle due to excessive heat and humidity which results in undue plant stress and overall poor growing conditions. The farm resides in a creek bottom where natural ventilation is limited and therefore ventilation inside the environment of the high tunnel is very poor. We have seen a variety of fungal diseases develop inside the high tunnel on crops including lettuce, kale, tomatoes, peas, and carrots. We also have experienced very poor tomato production inside our high tunnel due to blossom drop as a result of high heat and humidity. We planted an earlier crop of determinate tomatoes in 2015 in attempt to avoid the hottest part of the season, but the excessive spring rainfall and early heat produced the same results.

    In communicating with our NRCS agent and several other high-tunnel growers, we have found that most high tunnels in our area are out of production during the warm season. The small size of our farm limits our ability to forego using the area covered by our high tunnel. The stated goals of the USDA NRCS High Tunnel Initiative include ‘extending the growing season’ and ‘improving plant quality’, however, the warm season conditions inside most high tunnels runs counter to those goals.


    We propose to install one 50" solar-powered exhaust fan in each high tunnel end wall and 8 solar-powered horizontal air flow (HAF) fans in the interior of the high tunnel in order to provide sufficient air exchange for proper plant respiration and health and to reduce fungal disease prevalence. The fans will be powered entirely by solar energy and will provide variable rates of air exchange based on the intensity of the sun. The exhaust fan in the back wall of the high tunnel will push outside air into the tunnel while the exhaust fan in the front end wall will pull inside air out which will prevent the inside air temperature and humidity from rising too far above the outside air temperature and humidity. The HAF fans will keep inside air circulating in order to provide more uniform temperature and humidity throughout the interior as well as replace air at the plant level with air that has a higher carbon dioxide level.

    Our goal is to create an environment inside the high tunnel that is sustainable for good crop growth through most of the year. We have experienced an increased prevalence of fungal diseases in recent years and the high tunnel provides better controls for moisture on plant leaves and soil splashing onto the plants, which both contribute to fungal disease development. However, the hot and humid conditions that can be present inside the high tunnel counteract the aforementioned controls. We hope that if our plan is successful, other high tunnel growers will implement this strategy in order to fully expand the benefits a high tunnel can provide.

    Project objectives from proposal:

    1. Create an environment inside the high tunnel utilizing solar-powered exhaust fans and horizontal air flow fans to improve warm season growing conditions for sustainable crop growth through most of the year.
    2. Help farmers maximize profits by extending the growing season and improving use of high tunnel area.
    3. Benefit the environment by using solar energy, and using high tunnels to more effectively control weeds and pests without use of chemicals and prevent soil erosion.
    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.