How to Build a Hoop-style Greenhouse

Reader Contribution by Ric Bohy
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<p>Let’s pause in the narrative and build a greenhouse.</p>
<p>It isn’t difficult, using the design I found online from the North Carolina Cooperative Extension Service, and put to good purpose on

<br class=”Apple-interchange-newline”>Shuddering Squirrel Acres. This “hoop house” is also one of the most economical structures you’ll find. I made a few mistakes. We’ll get to them later. Learn from them.</p>
<p>The first step is to choose a good location. It should go without saying that you want a piece of solid ground that’s relatively level and at least as large as the greenhouse base. It should be warmed by 6 hours or more of direct sunlight out of 24 hours in winter, ensuring longer exposure in summer. Orient the greenhouse so it sits lengthwise east to west (or for that matter, west to east). This too will ensure the longest exposure when the sun is shining. A tree line, wall or other shelter from rough winds is desirable but not essential.</p>
<p>And don’t forget that you’ll certainly need water and possibly electricity,so plan accordingly.</p>

<p>I looked around online to find the greenhouse that made the most sense to me as a handyman and woodworker, and for which I could spend the least amount of money. Vicki, who’d long held a wish for her own greenhouse, said a footprint of about 10′ x 12′ would be good.</p>
<p>I settled on a <a title=”set of simple plans from the NCCES” href=””>
<u>set of simple plans from the NCCES</u>
</a>. First off, it’s a public document (free!). It includes a materials list, which is a bigger convenience than you might think, and a very cleanly drawn illustration of the frame, with each component numbered. I’d only ever built one structure, a small wooden storage shed, but these instructions were clear enough that I wouldn’t make too many knucklehead moves.
<p>The plans are for a 12′ x 14′ greenhouse shaped like a Quonset hut made with PVC pipe for its frame, and covered with plastic film. The base is a simple wood rectangle made of pressure-treated 2″ x 6″ pine boards. A few more boards frame the end walls and door. The floor is gravel.
These are all fairly inexpensive materials and easy to work with. (By far my biggest original expense, around $150, was the delivery charge for my gravel. But I spread the cost by ordering enough for the greenhouse floor and to repair and grade our long drive, which takes a pretty hard beating in heavy rains.)</p>
<p>Unless your land consists primarily of rocks in a matrix of clay, you’ll have an easier time preparing your site than I did. My advantage was in having a small John Deere tractor equipped with both a front loader and backhoe. Without it, doing anything with our land would be a fearsome challenge.</p>
<p>I chose a patch pretty well sheltered by our tree line on the south and our house on the north. It gets plenty of sunlight, enough that the adjacent pie pumpkin and gourd patch did the best of all our gardens last summer. We’re on a hilltop and there is no level ground, so there was the added
work of leveling the site and digging a shallow trench along the high side to minimize backfilling on the low. (Look at the photos and you’ll see what I mean.) This step, by the way, is the heaviest work in the whole project, so don’t let it get you down.</p>
<p>Another note to encourage you: Vicki and I worked together to get the frame base square and assembled, and to cover the PVC frame with its plastic sheeting. Everything else I was able to do alone. </p>
<p>The plans are clear for each step, so I’ll just give you the overview:</p>
<p>After the site is prepared, sink four corner posts and nail on the baseboards.</p>
<p>Put down a gravel floor at least a couple of inches deep, and rake it level.
<p>Lay out the PVC pieces as they will be assembled, then carefully glue and fit them together. Once dry, prop up the frame with a ladder under each end of the center rib, letting the side ribs hang down.</p>
<p>Another note: I was able to do the next step alone, although it took some acrobatics and finagling. Better to have a helper here. Best to have three.</p>
<p>Attach the bottom of each rib to the outside of the baseboard using metal straps and screws. I found it was much easier to position the straps first and attach them loosely, then shove in the pipe and tighten down the screws.</p>
<p>Nail and screw the wooden end frames in place, build the door and hang it. Attach each end rib to the end frames.</p>
<p>Now cover the whole thing with plastic sheeting. Sounds easy. It isn’t. This is where a good measure of patience is called for as you and a co-worker get the cover in place, making sure there’s an equal amount of overhang on each side, folding over the ends — something like wrapping a very large, oddly shaped gift — and then fixing the cover in place. We used a staple gun around the base and on each end, and black Gorilla Tape on the seams. These were the second and third mistakes.</p>
<p>The first one, in an attempt to save some cash, was buying what our local Lowe’s sells as greenhouse plastic. (Hint: It isn’t.) The largest piece it stocks is only a little more than half of what we needed, so that meant seams. These required something to join them, so I bought the Gorilla Tape thinking it could handle about anything. The plans suggest using staples to attach the plastic sheeting to the frame, but we found they tend to rip right through the plastic.</p>
<p>My biggest error was underestimating the effect of UV rays on plastic, including tape. After just one summer, and as soon as the air got chilly, our plastic became so brittle that it split under the slightest pressure. The black Gorilla Tape not only came loose, but was unsightly. We spent a few extra dollars to replace it with UV resistant “greenhouse tape,” but that too fell short.</p>
<p>Now, halfway through the first winter after its first summer, our greenhouse is stripped to the bones, a PVC skeleton. I recently did what I should have done in the first place and ordered strong U<a title=”V resistant plastic made specificallyfor greenhouses” href=””>V resistant plastic made specifically for greenhouses</a> through an online source that specializes in this stuff. It’s also large enough to cover our greenhouse with a single piece.</p>
<p>When the weather begins to warm, we’ll put it in place and attach it using plastic clamps made specifically for the job. We’ll seal the bottom with tack strips instead of staples, and I plan to devise a misting system from PVC to keep our plants watered. Of course, when the time comes, I’ll let you know how that works out.</p>
<p>Meantime, we’re reading seed catalogs.</p>
<p>(Say, please check out my personal blog on Shuddering Squirrel Acres. It’s called, <u>
<a title=”” i’m=”” mildly=”” concerned=”” that=”” one=”” of=”” my=”” hens=”” is=”” a=”” rooster…””=”” href=””>”I’m mildly concerned that one of my hens is a rooster…”</a>.</u>
<em>Photos by Ric Bohy</em>