What is a High Tunnel? High Tunnels, also called hoophouses, look very similar to a greenhouse, but are different because they are not a permanent structure and crops are usually grown in the ground instead of above ground like in a traditional greenhouse. High tunnels are not covered with glass or rigid panels, but with 1-2 layers of greenhouse grade plastic sheeting (polyethylene).
There are no standard dimensions for high tunnel sizes, but they typically fall within the ranges of 14-30 feet wide by 30-96 feet long. Usually, some form of irrigation is required for inside the structure. As the name implies, they are tall enough to walk-in comfortably and to grow tall trellised crops. Most high tunnels are passively ventilated via roll-up sidewalls and end walls that can be opened or removed
There are two basic designs of High Tunnels, Gothic and Quonset. While the Gothic style is usually more expensive, it does have several important features that are worth considering. Gothic style tunnels shed snow better, have more usable space along the sides, and feature better air exchange capabilities and interior moisture control.
*Images from University of Vermont Center for Sustainable Agriculture -
How long have High Tunnels been in use? Some form of "protected agriculture" has been done for centuries. From heating glass houses with open fires or manure, to cold frame and Ball jars, to straw mats and translucent paper, people have tried many types of this kind of agriculture. It wasn't until 1948 when the first documented use of polyethylene as an agriculture cover occurred at the University of Kentucky.
What types of plants are most often grown under a High Tunnel? Typically bedding plants, cut flowers, foliage plants, nursery crops, and vegetables.
How are crops grown in the Seasonal High Tunnel System? Crops can be grown by either using conventional tillage in the natural soil profile, or by installing permanent raised beds under the tunnel.
What are some benefits to using a High Tunnel? High tunnels are used to extend the growing season for crops by approximately two-three weeks on each end of the season by increasing the temperature surrounding the crop and minimizing the heat loss during the night. In general, each layer of polyethylene provides one hardiness zone of protection. If row covers are used within high tunnels, they provide additional protection from cold temperatures . High tunnels also provide crop protection against bird damage and other environmental factors can lead to pest and disease problems.
With high tunnels, producers can grow a variety of goods economically and efficiently. Compared to open fields, growers can get high value products to market sooner than the competition, and keep the product growing longer into the fall. It is also possible to keep growing certain crops throughout the winter.
Some farmers are diversifying their farm by introducing High Tunnels into their existing operation.
What are my options for irrigation?
Watering by hand - useful when crops are first seeded, but this means dragging a garden hose around and which is more work and potentially damaging to plants
On-ground pivoted sprinklers - This is a relatively cheap and easy watering option, but it can delay working inside the tunnel until the soil is dry
Drip/trickle irrigation - This method is very efficient and precise, can also deliver pesticides and fertilizers, and you can work in the tunnel while watering is occurring
Overhead delivery - All the foliage will get wet and potentially be easier to spread disease among plants
How do I control pests in a High Tunnel? It's not uncommon for pest and disease problems that occur in greenhouses to also show up in high tunnel structures. Common insect pests found during Penn State trials in Central Pennsylvania are whiteflies, aphids, thrips and spider mites.
The best way to deal with pests in a High Tunnel is through Integrated Pest Management (IPM) - 5 management strategies in combination with one another to decrease the need for pesticides. These methods are cultural (sticky traps, row covers), mechanical (conservation tillage), biological (natural enemies), genetics (cultivar selection), and chemical (pesticides)
What about Disease Management? When cropping a high tunnel, the importance of crop rotations are just as strong as if it were in an open field. After crops are harvested, residues should be removed and/or incorporated into the ground. Environmental management, such as allowing for proper ventilation for moisture and temperature will help break disease cycles.
Be sure not to crowd your plants and create a situation where leaves are overlapping and able to easily spread disease. Disease can spread from tunnel with traffic walking tunnel to tunnel so all hands, feet, and equipment should be clean
Can I get financial assistance installing a Seasonal High Tunnel System? Financial assistance is available through the USDA-Natural Resources Conservation Service via the Environmental Quality Incentives Program (EQIP). Keep in mind that there are certain rules that govern this program, ie the high tunnel cannot be heated and crops must be planted directly into the soil beneath the tunnel. Please also see the Financial Assistance discussion forum and this link for more information. Persons interested in participating in EQIP should contact their local NRCS office to discuss eligibility and program requirements.
What factors should I consider when deciding where to place my Seasonal High Tunnel System? Typically high tunnels should be sited perpendicular to prevailing winds and with the long axis oriented to give maximum exposure to the sun. Make sure there is a place for roof runoff to go. An ideal location would be one that is level, protected from the wind, and south-facing.