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Seasonal High Tunnels for Crops

Seasonal High Tunnel System for Crops - North Carolina


NRCS in North Carolina is providing financial assistance in Fiscal Year (FY) 2011 for seasonal high tunnels as part of a three-year national trial to determine their effectiveness in conserving water, reducing pesticide use, maintaining vital soil nutrients, and increasing crop yields.

Frequently Asked Questions           

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What is a Seasonal High Tunnel System for Crops?

A seasonal high tunnel system is a polyethylene (plastic) covered structure that is used to cover crops to extend the growing season. They are also known as high tunnels, hoop houses, or cold tunnels. They are used to extend the growing season for crops by approximately 2-3 weeks on each end of the season by increasing the temperature surrounding the crop and minimizing heat loss during the night.  

Are Seasonal High Tunnel Systems the same as Greenhouses?

No. The seasonal high tunnel system depends on the plastic covering to raise temperatures within the structure. Temperatures in the high tunnel during the growing season are controlled by using manual roll-up side vents and by opening end doors to provide ventilation. Unlike greenhouses, seasonal high tunnel systems as indicated by their name are seasonal and are considered temporary structures. The standard does allow producers to install electrical, heating, and ventilation systems at their own cost.  

How are crops grown in the Seasonal High Tunnel System?

Crops can be grown either in the natural soil profile or by installing permanent beds. Seasonal high tunnel systems installed under the Environmental Quality Incentives Program (EQIP) are not allowed to be used for crops grown on tables/benches, on logs, or in portable pots.  

Are row covers or low tunnels considered a Seasonal High Tunnel System eligible for EQIP?

No. In order to qualify as a seasonal high tunnel system under EQIP the tunnel system must be a minimum of 6 feet in height; therefore, row covers and/or low tunnels do not qualify.  

Are Seasonal High Tunnel Systems moveable?

Some systems are movable and can be rotated to different locations in support of a sound crop rotation. However, moving a high tunnel not specifically designed for movement can negate the manufacturer’s warranty on the system; always check with the manufacturer first- if you want a moveable high tunnel. 

How can the EQIP Seasonal High Tunnel Initiative help me install a High Tunnel System?

The EQIP Seasonal High Tunnel Initiative is a voluntary program that provides financial and technical assistance to agricultural producers. The goal of the initiative is to assist producers in extending the growing season for high value crops in an environmentally safe manner. Persons interested in participating should contact their local NRCS office. EQIP participation requires applicants to meet specific eligibility requirements. The high tunnel must remain on the land enrolled in EQIP for a minimum of four years. Therefore, if the applicant is not the landowner, the landowner must provide written permission for the high tunnel to be installed on the land for the four year period. The land submitted for the program must be currently in cultivation or presently be capable of being planted to a crop (i.e. cultivated land in a fallow condition). Land presently in permanent cover such as hay, pasture, brush, or forest does not qualify. Interested applicants with land not ready for high tunnel installation may request a plan to prepare the land for crop production from our local conservation staff and partners. This plan is especially important for organic production systems due to restrictions on chemical vegetation control options.  

Applicants must be agricultural producers and must be in compliance with the highly erodible land and wetland conservation compliance provisions of the 2008 Farm Bill. Applicants will work with NRCS to finalize the details of planning and site selection before the application is submitted for ranking and funding consideration. Applications selected for funding will proceed into the contracting phase. Program contracts will be developed that outline practices to be installed, payment rates, schedule for installation and operation and maintenance requirements. EQIP payments cannot be received for practices installed prior to contract approval.  

What are the structure requirements for a Seasonal High Tunnel System under EQIP?

Under EQIP the seasonal high tunnel system must be obtained as a pre-fabricated kit directly from the manufacturer or from a supplier. The frame shall be constructed of metal, wood, or durable plastic and be at least 6 feet in height. The plastic cover must be, at a minimum, a 6-mil greenhouse-grade, UV resistant polyethylene. Individuals must work closely with the high tunnel supplier to select the best design, materials for their operation and for help with installation of the high tunnelaccording to the manufacturer’s instructions.  

When selecting a kit, individuals should consider factors such as design, mobility of structure, adaptability to additional ventilation/heating equipment, strength/design for snow and wind loads, type of anchoring system required, strength/thickness/light transmission of the polyethylene cover, venting method (roll-up or drop-down sides) and warranties provided on the frame or covering. Individuals should look for manufacturers that offer kits providing warranties of at least 4 years for the plastic covering and 10 years for the frame structure.  

How do I find a manufacturer or supplier of Seasonal High Tunnel Systems?

Start locally. Many local farm, building or greenhouse suppliers sell kits. One of the easiest ways to find a manufacturer or supplier is to use an internet search engine to search: “High Tunnel”. Another good place to find links to manufacturers or suppliers is to visit high tunnel information websites, such as .  

What size Seasonal High Tunnel Systems are available?

Systems “kits” are available in all sizes and dimensions. Under EQIP, contract payments can be made on seasonal high tunnel systems installed on cropped areas of up to 2,178 square feet. Structures can be larger; however, contract payment is limited to 2,178 square feet per producer. 

What usually comes in a Seasonal High Tunnel kit?

Basic kits usually include the frame structure and assembly hardware; polyethylene cover with roll-up or drop-down side assemblies and heavy duty ground posts. Optional items include manufactured end panels and/or door assemblies, as well as top and bottom baseboard kits.  

What factors should I consider when siting my Seasonal High Tunnel System?

Seasonal high tunnel systems should be placed perpendicular to prevailing winds to insure proper ventilation and if possible, with the long axis oriented in a north-south direction to provide more uniform sun exposure to plants and minimize plant shading. Systems should not be located in areas prone to shade or wind gusts. Look for sites with topography that allows for adequate drainage away from the structure. Many kits can be modified for installation on areas with a 1-2 percent grade along one axis (generally the length side) but most cannot be installed on areas with two directional slopes. Consult your manufacturer or supplier for specific guidelines. At sites where runoff away from the structure is problematic, a stable outlet shall be established to prevent erosion and/or ponding of water. Systems should also be located in areas that allow for convenient ingress/egress of plant materials and equipment. Because irrigation will be required inside the tunnel, availability and source of water must be considered when deciding where to place the system.  

What requirements are there for maintaining and operating my Seasonal High Tunnel System?

EQIP regulations require that the system be functional for a minimum of 4 years. Due to this requirement, participants should utilize caution in selecting the seasonal high tunnel system kit and select one which will remain functional throughout the contract period. Maintenance and repair of the system is the sole responsibility of the contract holder. If damage occurs, contract holders should be prepared to bear the costs of making repairs or replacing the polyethylene cover during the contract period. The EQIP does not provide any additional payment to aid in the repair of structures. In climate conditions where snow loads may damage the structure, the tunnel cover shall be removed or rolled up at the end of the growing season unless the structure is designed to withstand expected snow loads. Polyethylene life depends on the quality of installation, operation and weather factors. Several ways to help increase the lifespan of the polyethylene covering is to place the rafters’ close enough to minimize flapping in the wind, cross brace the structure to prevent vibration in the wind, sand the rafters smooth prior to installing polyethylene or wrapping rafters with plastic, installing cover on a warm day to get plastic tight, keeping farm implements and people off the polyethylene and making sure structure is well anchored. Contact your specific manufacturer for additional suggestions.

What other practices would be good to use with a Seasonal High Tunnel System?

Additional conservation practices could include: conservation crop rotation, mulching, diversion, irrigation water management, nutrient management, pest management, and critical area planting.

Your local NRCS office can provide you with more detailed information, as this fact sheet is general in nature and does not include all program requirements and/or details.

National Seasonal High Tunnel information

Seasonal High Tunnel Systems for Crops Conservation Practice and Ranking Documents

The following documents require Adobe Acrobat, Microsoft Word, or Microsoft Excel

2014 Payment Schedule, Seasonal High Tunnel Systems for Crops (PDF, 66 KB) (Last Modified 12/13/2013)

Program Contact

Greg Walker, Assistant State Conservationist for Programs, 919-873-2104