Organic Broadcaster

Hoop houses offer many benefits to diverse market farm

By Dave Bishop

A hoop house—or high tunnel, if you prefer—can be an important addition to a diverse farm operation, providing a protected growing environment and extending the growing season. At PrairiErth Farm, we’ve constructed six hoop houses over the past 20 or so years; the latest one—a 30 x 150—we built just this spring. We’re still using all of them.

Our hoop houses have helped us produce and market fresh fruits and vegetables (and retain good employees) year round—even in Illinois, where winters can be relatively snowy and cold. If you happen to live in a part of the country where winter tends to drag on, and on, and on, a hoop house can be both a good investment and good for your spirits. There’s something about walking out of the house on yet another bitter winter morning, face set against the sharp air, crunching through the snow, and stepping into a hoop house with green crops and that sweet earthy smell of spring! There’s definitely a “magic-factor” to be considered.

To help you decide if a hoop house might work on your farm, consider these insights harvested over the years on our farm.

Value, Cost, Payback

Cool-season salad mix fills one of the hoop houses at PrairiErth Farm in Illinois. All photos by PrairiErth Farm

The first consideration is exactly how this investment will fit into the operation as a whole. For us, hoop houses make it possible to supply our customers with perishable greens like salad mix, spinach, or kale year round to go with the potatoes, carrots, and other veggies we fall harvest and store. Since we also produce grains and livestock, we can provide those customers with a wide variety of products. So the investment made in obtaining a customer—whether it’s an individual, store, or restaurant—is more rewarding by having a wide variety of products to offer them.

Financial assistance can be obtained through farmer grant programs such as SARE or local foundations, or through the Natural Resources Conservation Service’s EQIP initiative. We’ve found that, even without financial assistance, hoop houses can have a short payback period of two or three years if managed intensely.

Site Selection
You’ll need to provide electrical service and water, and you’ll be checking it frequently, especially during early spring and late fall, so easy access is important. About mid-January, I start wishing the house was directly connected to one of our hoop houses.

Many counties don’t require a building permit, but it’s a good idea to check. Site the hoop house far enough from trees so they won’t shade or fall on it.

Orientation is also a consideration. Generally, if you live above 40 degrees N latitude, orient the length of an individual structure east to west. If below 40 degrees, orient north to south. If you happen to live right on 40 degrees N as we do in central Illinois, it really doesn’t matter. (If you are planning multiple gutter connected structures, orient north to south at all latitudes. This orientation avoids the shadow that would occur from the structure just to the south of it in an east-west layout.)

Hoop House Types

Gothic hoop houses have additional roof support structures that can hold hanging fans or plant trellises.

There are many fine companies offering a wide array of designs and options. Peruse their websites, speak with representatives of different companies, and ask if there are examples of their products in use near you. Time spent visiting with other farmers about their hoop houses and how they use them is invaluable!

Essentially, there are two main structural designs for high tunnels: Quonset and Gothic. Quonset structures have a round roof with slightly shorter and curved sidewalls, while Gothic structures have a pointed peak (A-frame) with additional supports across the peak. Gothic structures tend to shed snow and ice better than Quonset structures. Gothic structures also allow for a peak or gable vent to be added to the structure which facilitates air movement and ventilation. We have built both types, and have found Quonset structures to be less expensive.

Doors are hinged on 4×4 posts set 4 feet in the ground. In areas subject to high winds and thunderstorm wind bursts, strong end walls are extremely important. Most of the damaged hoop houses I’ve seen had weak end walls.

Site Preparation
You can’t tell if a site is level by just looking at it. Get a transit or, if you’re not an experienced land contractor, hire one to prepare a level site and install proper drainage—it’s way cheaper than “fixing it” after the fact.

Once the site is leveled and proper drainage is installed, it’s critical to get the ground stakes installed (setting them in concrete isn’t a bad idea) at the correct elevation and positioned so the building is square. If you don’t have experience with that sort of thing, hire someone who does. If the foundation isn’t right, nothing else will be either. Once that’s done, assembling the frame is pretty straightforward.

Intense Management
To get the most value from the investment, a hoop house must be intensely managed—that means someone has to be present on a daily basis. That’s generally not a problem for farmers like us who raise livestock that also require daily attention.

Here in central Illinois, we begin planting (or transplanting) cool season crops like salad mix and spinach in late February. By mid-April, tomato starts replace the harvested early crop, or can be planted directly into remaining cool season crops. They’re usually gone before the larger warm season plants can shade them out. In October, warm-season crops are replaced with a new planting of cool-season crops for harvest throughout late fall and winter.

This hoop house features a hot water root zone heating system under the grow tables and a heated germination chamber.

To start transplants, we put seeded flats in a well-insulated germination chamber kept at 85 degrees for two or three days. Then we set out the flats on grow tables. Beneath the black cover on the grow tables, rows of tubes circulate hot water to keep the soil temperature in the flats ideal for plant growth. We have a forced air furnace for extreme temperatures or night freezes when tomato seedlings are vulnerable.

We use plenty of fans to keep air circulating, to maintain an even temperature throughout the building, and to “harden off” tender plants before transplanting.

Side curtains provide the primary means of temperature control and require frequent monitoring, especially during early spring and late fall. Roll-up (and down) options include manual hand cranks, mechanized systems, and fully automated systems that are controlled by a thermostat inside the hoop house.

Fans are also important, especially during hot, humid, and still mid-summer conditions when micro-climates are likely to develop. Horizontal air movement is needed to maintain a uniform temperature inside the structure and to reduce the incidence of foliar disease.

The side curtains tend to wear out before the roof from the frequent rolling up and down. We use a double channel hip rail mounted 5 feet above the ground to secure the plastic. This allows the lower curtain to be replaced independently of the roof.

The farm’s hoop houses are covered with 2 layers of 6 mil poly. Inflator fans keep the plastic taut so it doesn’t whip in the wind, a sure way to shorten the life of the plastic.

The plastic on our hoop houses lasts about six years. Plastic has come a long way in terms of durability against photodegradation. It’s the whipping from wind and rain that really beats it up. Plastic naturally shrinks as it cools and stretches as it warms. The only way to keep it taut is with an inflator. Plastic is expensive—invest in a good inflator to keep your plastic in good shape so it lasts as long as possible.

Just as outdoors, it is the combination of plants and animals on the land that creates regenerative farming systems. We graze broilers on cover crops in our hoop houses as part of the rotation. This practice helps restore fertility and break up pest and disease cycles.

Trial Run
Rather than investing in an expensive hoop house right out of the gate, cash-strapped beginning farmers could get creative and build something out of supplies on hand. That’s what we did for our very first hoop house some 20 years ago. We were experimenting with a vegetable crop enterprise and direct marketing. We made a half-acre commitment, growing mostly tomatoes and sweet corn. We cobbled together a 10×12-foot wood frame with cattle panel ends and a roof covered with cheap plastic. The purpose of this mini hoop house was to start tomato plants. It worked very well, except for the plastic, which disintegrated in a few months. We’re still using that structure today as a storage shed (with a newer plastic covering).

The Bishops, the 2017 MOSES Organic Farmers of the Year, farm at PrairiErth Farm in Atlanta, Illinois. Farmers interested in hoop house production/construction can email dave@prairierthfarm.com.

 

 

From the May | June 2019 Issue

 

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