Installing a high tunnel

By Rennie Phillips

Probably eight or nine years ago I was reading an article on raising vegetables in a special kind of greenhouse called a "high tunnel." A high tunnel is pretty much just like a greenhouse except one can open up both the ends and the sides to allow for ventilation. So they are virtually a garden with a plastic cover.

One of my favorite places to buy garden seed is located near Jefferson City and it turned out they had high tunnels listed in their catalog. So I did some reading and studying and found out the high tunnels were actually made in Versailles, Missouri. So I did some more checking and found I could buy a high tunnel directly from the maker and didn't have to go through a supplier.

One can orient the high tunnel either east and west or north and south. We had a perfect spot close to our house for a high tunnel to run east and west. It was surrounded by trees but it wasn't shaded most of the day so it was a perfect spot. We measured it and found we could put about a 48-foot high tunnel in this spot. After some more measuring and a bunch of figuring we decided to buy two 24-by-48 foot high tunnels and put them side by side. So we ordered our high tunnels. Shipping was about $300 on each tunnel so I talked to a friend and he drove to Versailles and hauled them right to our place. The next task was putting them up.

The ground needed some dirt work so we graded two spots pretty level. I used a blade on one of our 135 Massey Fergusons to move the dirt around. All it took was time. Little by little we got the spots for both high tunnels leveled and ready for the construction phase. So we measured and marked off the four corners. We used an auger on our tractor to dig the holes and then seated the four pipe corners in concrete. We then stretched a string from corner to corner along the sides. This gave us the location of the other vertical posts. We put a pipe every six feet along the outside of each side. These we put in concrete as well. Everyone said they didn't need to be in concrete, but I felt like they needed to be.

We did as much of the work on the ground so there wasn't very much ladder work. Once we had the top on the tunnels and the ends up we then began to cover them with plastic. We used 6-millimeter plastic guaranteed to last four years. Man, it is tough stuff. The top and ends went on a lot better than I expected. After stretching them over the top and ends we secured them with a plastic strip and nails. The tunnel came with a channel where the top was secured. It was pretty easy. After getting the tunnel constructed we went to putting water in both tunnels. We dug the lines down two feet with shovels. If I had to do it over, we'd hire a backhoe. But we got it done.

We first planted a cover crop of turnips in both tunnels. The seed is pretty cheap and comes up pretty good. Once it gets up and growing, it doesn't require much water. It sure was pretty with all that green growing in the tunnels.

We have tried to grow about everything in them. We grew some of the prettiest green beans in one of the tunnels. That year we planted jade green beans. We planted some beets one fall. We even waited till spring to dig them. Some were a little pithy but mostly good beets. One year we planted zucchini in one tunnel. It just didn't do very good. I don't think we had enough pollinators, so I began buying zucchini seed that didn't need a pollinator. That worked really well.

The two crops that seem to do the best in the high tunnels are cucumbers and tomatoes. We have raised a boatload of both in our two high tunnels.

The one thing I've noticed about the tunnels is they seem to concentrate bugs, which just tear up vegetable plants. There is a squash bug that kills the cucumbers right at the ground. These squash bugs tear into the stems and kill the cucumber vine. One can spray for the bugs, but after spraying I hesitate eating the veggie. So we pick and eat cucumbers until the squash bugs kill the cucumber plants.

We have never had aphids in our high tunnels until this year. The aphids were hard to deal with. We tried all kinds of organic ways of getting rid of them, some of which helped. But along with the aphids there was a little yellow-and-black-striped bug that ate the blossoms on the tomato plants. Those are the little buggers that caused the damage. I finally sprayed with Malathion, one of the old insecticides. It seemed to do the trick.

For the past seven or eight years the Natural Resources Conservation Service (NRCS) has assisted landowners with purchasing high tunnels. The goal seems to be that homeowners will begin growing veggies at home. If you have wondered about a high tunnel, get in touch with your local NRCS. It won't hurt to check.

You can also put up a small version of a high tunnel using local materials. We built a 12-by-20 foot greenhouse using materials I bought at local stores. About the only thing you would have to order is the plastic. It's best to buy plastic made specifically for greenhouses or high tunnels. It will withstand the sun's rays and not fall apart.