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High Tunnel Buyer's Guide - Growers Supply

High Tunnel Buyer's Guide

What is a high tunnel?

High tunnels are hoop houses covered with greenhouse film or woven polyethylene fabric that will help increase crop yields and extend the growing season. Many growers, from hobbyists to professional and commercial growers, see high tunnels as the step between field growing and greenhouse growing. High tunnels have been widely used in Japan and Europe for many years and are becoming increasingly popular in the US. The US government has even funded a program to encourage farmers to install high tunnels. Farmers use high tunnels to grow many different types of crops, including strawberries, raspberries, tomatoes, beets, carrots, cucumbers, eggplants, peppers, radishes, squash and herbs, as well as roses and a variety of flowers. Growers Supply offers a range of high tunnel sizes, from 14' to 42' wide and 5' to 19' tall. Growers Supply's high tunnels also come in a variety of lengths and customers can connect multiple high tunnels end-to-end in order to create any length high tunnel they want. Many accessories are also available, including zippered roll-up doors, roll-up or drop-down sides and extra rafter kits.
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What makes a high tunnel different from a greenhouse?

Many people are familiar with greenhouses and how they increase crop yield. High tunnels are similar, but simpler and less expensive. Greenhouses usually have a double layer of air-inflated polyethylene plastic that remains installed year round. High tunnels, however, have only a single layer of greenhouse film or woven fabric that can be applied and removed as needed. In high tunnels, heating systems are usually not employed, though sometimes growers choose to use space heaters to help further extend their growing season. While greenhouse plants are usually established in containers, plants in high tunnels are usually grown in ground, although containers and media such as raised beds can be used. Our Expert Gro Slabs and PolyMax® Grow Tubes offer more growing options and benefits. Growing in ground is made possible in a high tunnel because there is no foundation—high tunnel frames and supports are driven directly into the ground.

High Tunnel Buyer's Guide - Growers SupplyWhy should I use a high tunnel?

High tunnels are a great and simple way to increase your crop yield. Most importantly, they extend the growing season. By protecting plants from the elements and providing insulation, the ground takes much longer to freeze inside a high tunnel and frost damage is reduced for an extra 3 to 4 weeks on each end of your growing season. This allows growers to start planting earlier and harvest longer. Plants grown in high tunnels are also healthier than plants grown in the field; high tunnels protect plants from wind, reducing stress and possible photosynthesis shutdown. Furthermore, high tunnels keep out harmful driving rains, allowing you to maintain an appropriate and constant moisture level with your own irrigation system. High tunnels also reduce overall labor.

Soil warming, wind and rain protection, and reduced labor and operating costs are not the only benefits of a high tunnel. In the field, disease, insects, pests and wildlife can threaten your crops. All of these harmful factors are greatly reduced by high tunnels. By controlling the moisture, sun and heat within your high tunnel, you will reap the benefits of better-flavored produce earlier.

Choosing and Constructing a High Tunnel Frame

As one of the largest high tunnel manufacturers in America, Growers Supply offers many styles of high tunnels, from Single Bay to GrowSpan Premium, in both gothic and round style. Use different styles of high tunnels in your fields to best utilize their protective abilities and maximize your crop yield.

Growers Supply's Single Bay Tunnels can be connected to make Multi-Bay Tunnels. Multi-Bay Tunnels are useful in covering large acreages. Sometimes it can be difficult to regulate temperature over such a large area, so Mutli-Bay Tunnels are often used as shelters from rain and wind.

Round Style High Tunnel - Growers Supply
Round Premium High Tunnel
Gothic Style High Tunnel - Growers Supply
Gothic Premium High Tunnel
Single Bay High Tunnel - Growers Supply
Single Bay High Tunnel
Multi Bay High Tunnels - Growers Supply
Multi Bay High Tunnels
Rolling Premium Round Style High Tunnels - Growers Supplu
Rolling Premium High Tunnels
USA-made, triple-galvanized structural steel tubing - Growers Supply
USA-made, triple-galvanized structural steel tubing
used in many GrowSpan High Tunnels

Our GrowSpan high tunnels utilize premium, 18-gauge galvanized roll-form frames to ensure strength, durability and long life. Other tunnels, like our GrowSpan Round Economy and Round Premium high tunnels have frames constructed from our USA-made, triple-galvanized structural steel tubing.

Many options, sizes and styles are available depending on your growing needs, climate and location. Roll-up or drop-down sides and zippered ends make ventilation easy within your high tunnel. From our GrowSpan Mini Cold Frame for the hobby grower to our large High Tunnels for the commercial grower, there is one for every growing need.

Roll-Form Pro Solar Star High Tunnel - Growers Supply
Series 500 Tall
High Tunnels
GrowSpan High Tunnels - Growers Supply
High Tunnels
Premium Round Style High Tunnel - Growers Supply
Round Premium
High Tunnels
Economy Round Style High Tunnel - Growers Supply
Round Economy
High Tunnels

Construction is easy with our simple, detailed instructions. When needed, our technical support group is only a phone call or email away. Construction crews are also available. Please Contact Us for further information.

High Tunnel Coverings

High tunnels are covered with a single layer of greenhouse-grade woven polyethylene fabric or greenhouse film. This is less expensive than greenhouse polycarbonate or double-layer plastic, and allows high tunnels to be opened when desired to help maintain the best possible climate conditions for your plants; leave the sides down to keep in heat during colder nights, or roll them up in the summer to let out extra humidity.

5.2 oz. Clear Woven Greenhouse Film - Growers Supply
5.2 oz. Heavy-Duty Clear Woven Fabric
6 mil 4 Year Clear Greenhouse Film - Growers Supply
6 mil 4 Year Clear Greenhouse Film
Anti-Condensate Thermal Greenhouse Film - Growers Supply
Anti-Condensate Thermal Film

Growers Supply's suggested greenhouse film for high tunnels is Sun Master® 6 mil4 year film, made from strong copolymer resin for strength and durability. Sun Master® Greenhouse Film contains anti-dust additives that repel dirt and dust to allow for 92% light transmission. Growers Supply also offers a variety of other greenhouse coverings, including 5.2 oz. Heavy-Duty All-Purpose Fabric, Anti-Condensate Thermal Greenhouse Film, and other films with different opacities to help you design the best possible high tunnel for your crops.
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How are high tunnels ventilated?

Tunnel ventilation is very simple and is one of the advantages of a high tunnel over a greenhouse. Temperatures in the high tunnel can be monitored by adjusting the sides, end doors and peak vents. Sides can be rolled up and doors can be opened fully or partially, depending on the ambient temperature. Frequently, growers will leave their high tunnels rolled up day and night in the summer, but close them at night during the spring and fall to protect plants from cold weather or potential frost.

Partially Open Drop-Down Curtain - Growers Supply
Partially Open Drop-Down Curtain
Roll-Up Sides - Growers Supply
Roll-Up Sides

Anchoring a High Tunnel

Since plants grown in a high tunnel are typically established in the ground, high tunnels are usually anchored in soil. Growers Supply offers two different methods of high tunnel anchoring: ground posts and mounting feet. Ground posts are driven into the ground about two feet. Setting posts in concrete is recommended. Mounting feet can be secured to a customer-supplied baseboard, concrete pier, footing or foundation. We recommend using a baseboard. Our Recycled Plastic Lumber comes with a 50 year warranty and is ideal.

Ground Posts - Growers Supply
Ground Post
Mounting Feet - Growers Supply
Mounting Feet
Recycled Plastic Lumber - Growers Supply
Recycled Plastic Lumber

High Tunnel Accessories

Growers Supply offers a variety of accessories for your high tunnels. For growers who want to significantly extend their growing season, heaters and thermostats are great ways to protect against the cold during the winter. Growers Supply offers a variety of heaters that range from forced hot air to radiant heat, in electric, natural gas or propane. Since your high tunnel's protective structure keeps out rain, an irrigation system is necessary to keep your plants healthy and productivity high. Growers Supply offers many different options for irrigation systems from drip irrigation, to misting systems, to sprinkler systems. Many customers make use of our timers and controllers to automatically maintain an optimal climate in their high tunnels. Customers in some locations also use our industrial and greenhouse fans to help keep the temperature constant throughout their high tunnel. Typically, tunnels are aligned with the prevailing wind to allow air flow simply by opening the high tunnel ends, but fans and/or vents can prove useful when heating your high tunnel in early spring and late fall, when these ends may be closed. Growers Supply offers many different types of circulating fans, exhaust fans and tube fans. For those high tunnels that only require roof vents, Growers Supply offers a variety of vents and louvers including solar-powered vents.
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Spring Wire & U-Channels - Growers Supply
Spring Wire & U-Channels
Irrigation Systems - Growers Supply
Irrigation Systems
Ground Cover - Growers Supply
Ground Cover
Growing Media - Growers Supply
Growing Media


High tunnels are a great way to increase your crop yield. High tunnels offer significant cost savings over similar size greenhouses, and for a low investment, they help bring in a large return. High tunnels help to extend the growing season and protect your crops and flowers from wind, rain, frost, insects, pests, disease and wildlife. They are made from a single layer of greenhouse film or woven polyethylene fabric that can be raised or lowered depending on the climate, allowing you to control the growing environment. Let Growers Supply's wide variety of accessories keep your high tunnel in peak condition, allowing you to reach your full growing potential.

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Read Customer Testimonials from High Tunnel owners
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