Project Winter High Tunnel

To every thing there is a season, and a time to every purpose under the heavens – Ecclesiastes 3:1

High tunnels, also known as hoop houses, are a marvel of simplicity. They differ from a greenhouse in that they don’t have an artificial heat source.

It’s just a frame, some plastic, and the sun that do the work of extending the growing season, allowing us to cultivate food year-round here in west central Indiana.

It’s an amazing tool that helps us have flowers in November, lettuce in December, greens in March, carrots in April, and even tomatoes in June.

High tunnels help protect against excess wind, excess precipitation, erosion, cold, soil compaction, as well as pests and plant disease (to some extent). We can open the sides completely to allow beneficial insects and breezes to enter and do their good work.

Due to the benefits of a high tunnel, space in them is at a premium. We rarely have a fallow row. In fact, it’s not unusual to pull an old crop out one afternoon, throw down and rake in some compost and organic soil amendments, and plant a new crop in the same spot the very next morning. Tomatoes on a Tuesday. Lettuce on a Wednesday.

It’s efficient. It’s productive. It’s regenerative. But it’s not a facsimile of nature. For all that we gain in a high tunnel by smoothing out the edges of the chaos that is the natural world, we lose some of the advantages that same chaos brings.

Without rain falling from the sky, pounding the earth, pushing salts and other minerals down in partnership with gravity, salinity in the soil can build up.

Salts that come from both the compost we use and the irrigation water we source stay in the top layer of soil. Crops don’t really like excess salts. Without freezing temperatures, pests like aphids and certain harmful nematodes can thrive, with populations growing exponentially.

The same warming benefits that create an environment for vegetables to continue growing in winter allow weeds to come along for the ride. Eventually, nature needs to be allowed in to do her time-tested work.

The plastic and lumber that are part of the structure need to be replaced occasionally, too. The manufacturers of the plastic that is the roof normally state a useful life of three years.

We normally try to squeeze a few more than that out of it. But, nature wants in. Holes will form from the weight of snow from winter storms. They can form from the impact of hail dropped by summer storms. Years of relentless wind can cause tears.

The same beneficial bacteria, fungus, and insects that improve soil also do their decomposition work on the wood that holds the structure together.

Nature wants in. And for good reason.

This fall and winter, if you’re on campus, you might notice one of our high tunnels looking a bit bare. Its metal rib-cage is exposed, and no crops are growing.

This isn’t because of damage. It’s not because of negligence. Rather, it’s an invitation. It’s humility. It’s balance. It’s time for a refresh.

It has been over six years since the roof was replaced. Even longer for much of the lumber and sides. We’ve started the process of removing the old and damaged parts.

However, instead of putting it back together immediately, we’re making time to allow the outside to come in. In consultation with both nature and Purdue University (who we’ve been working with on a soil study–more on that in a future post), we have opened it up so that she can help improve the soil, battle the weeds, and reset the pests.

The ground in the high tunnel can become reacquainted with winter, as every season has a purpose.

Just as all of nature seems to regenerate in spring, so will the high tunnel. After several months of dormancy, we’ll begin replacing parts and have it restored and ready to go in April.

Until then, we’ll patiently watch and appreciate the work that a truly balanced ecosystem can do.