By Carey Restino
Three years ago, I heard through the grapevine that a friend had built an inexpensive quonset-hut like structure to grow things in out of PVC struggling to grow things on a windy spot on Diamond Ridge, I was all ears. A tour followed, and I was sold on the hoophouse idea. Within a few months, I had dug down four feet into the snow to construct my first venture into plasticulture.
Up on the ridge, we still have a lot of snow, but down in the lower elevations, the ground is appearing, and with it, the opportunity to improve your growing potential exponentially with relatively little investment. While metal-framed, gigantic high tunnels are springing up all over town, you don’t have to dive into that world to see huge benefits to your gardening world. A little pipe and plastic is all it takes.
There are plenty of good ways to build a hoop house, and you can use all kinds of materials, but in my opinion, it’s best to keep it relatively cheap and easy. These structures aren’t going to last forever, and I don’t think it’s worth it to try to keep them up all winter, so your goal is essentially to create a bubble over your plants and warm things up during the growing season. That means PVC pipe, which you pretty much have to buy up the road anymore since plumbers have largely switched to other materials. Some people have used conduit successfully, and there is lots of talk about bending metal pipe, which is surely more long-lasting. But the hoop houses I’ve built cost less than $200 in materials. You can always spend more money, but eventually, your tomatoes start to cost a whole lot more than they are worth.
My first tunnels were based on the design that I first saw, and I still like it. They are built sort of like a light-weight tent, and they seem to hold up pretty well to wind. By chance I oriented my hoop houses with the long side running from north to south, which I’ve since learned is the better way to take full advantage of the sun.
I spaced my hoops 3 or 4 feet apart since I’m not trying to hold up snow. I got 3/4 inch PVC pipe in 10-foot sticks and a whole lot of X fittings. Then I cut 4-foot pieces of PVC to run along the top of the frame to keep the spacing tight. I have tried using a wooden 2×4 with holes drilled in it as a ridge beam, but the wood kept the whole structure from flexing in the wind, and the PVC chafed on the wood, so I am loyal to the lightweight design.
You can assemble the centipede-like PVC structure in eight- or 12-foot sections and then move it into place piece by piece. I highly recommend letting the PVC pipe glue cure really well, maybe even for a day, before bending it. If one of the fittings slides out after the fact, it is rather tricky to get it back into place, so you don’t want to push that envelope.
I made my tunnel 12 feet wide. That allows for enough headroom to avoid getting drenched with condensation when you walk in. I had pieces of rebar cut into two-foot chunks and sunk them 1 foot into the ground. My soil is pretty hard, but some people might want to put the rebar down deeper to avoid things moving around too much. Put the PVC pipe over the rebar on one side, then go to the other side and bend it into place. You should have a good bit of tension in the PVC.
I made my tunnel long enough to put a piece of 20-x-40-foot 6 mil plastic over. Since you need about 8 feet on either end to get the end-wall covered, that made my tunnel 24 feet long.
Once you put up all your PVC, hoops, I recommend running two pieces on either side that go from the center of the tunnel to near the top of the final hoop on either end, like a tent cross-brace. I attached these to the framework of the end wall and they make the whole structure a lot more solid. I used regular screws to attach the cross-brace to the PVC hoops where it crosses.
The end walls are open to creative framing. You will need to have cross ventilation going during the warm, sunny days, and it sure is nice to have a door on there. I built mine with a large removable panel at one end to allow a wheelbarrow or rototiller through, and a door at the other end. You probably want to be able to mount a fan on one end for very hot days. But don’t forget – the plants don’t care if your angles are perfect or the wood is salvaged scrap wood. You don’t have to get fancy.
The only thing left to do after this is pull the plastic on. I used sandbags to weight it down along the edges. They only lasted a couple years but the were easy to work with. A board with the plastic wrapped up and stapled on would work, too. A word of caution on plastic – not all cheap plastic is created equal. I bought some a couple years ago from Home Depot and it shredded on the first storm along all the seams. The plastic I have bought from Spenard Builders Supply is on its fourth year now and still holding strong. If you want guarantees, buy the more expensive greenhouse plastic.
And that, my friends, is it. It took me and two friends about six months to build a high tunnel on weekends – this hoop house project, by contrast, can take less than four hours if you know what you are doing.
If you put it up now, the ground under it will quickly thaw, allowing early tilling. I planted starts in a hoop house in town in mid-April last year and covered them with Reemay. Everything made it. Inspired yet?
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