Greenhouse construction

(In honor of Black History month, I've decided to spend some time educating myself about notable blacks; I'll append a brief note about some of my discoveries at the end of my posts.) 

Alley tr 1

This is one of several small greenhouses we put up last winter. I could have cropped this photo to emphasize the greenhouse, but I decided instead to emphasize how damn big and how damn numerous are the many trees in and near our yard. This structure, built against the side wall of the garage, faces due west towards the alley that separates our back yard from those of our neighbors. Alleys, like fences, make good neighbors.

Last year’s structures didn’t hold up too well against the weather, unfortunately; this one finally collapsed under the snow that slid off the garage roof, and others met equally ignominious fates. This fall, then, I went back to Eliot Coleman’s Four Season Harvest, and with a lot of indispensable help from husband Steve, adapted one of Coleman’s simpler models. His full-scale designs use metal tubes, not plastic, and even his simple ones have real doors with wooden frames. I kinda skipped that part.

This time around, with the okay from the great guys next door, I decided to build against the fence that bounds the west side of their yard, figuring that protection from storms would more than make up for the lost sunshine. (I'm not sure I was right about that.) Coleman and other sources too, I think, said that eastern exposure was most important, and this was just about the only place where that was available in any of the three (or four) yards where I have gardening rights. Here's the site back in early October when I'd just started prepping it. The beans were still producing, and the venerable zucchini, visible in the lower left, had not yet been touched by frost. 

Grnhs site, WIP

Coleman recommends sinking long pieces of rebar into the ground, running PVC pipe over them, then bending them into great hoops and stretching 6mm. plastic over all. PVC, as we’d discovered to our sorrow, just isn’t strong enough on its own, but rebar alone would abrade the plastic stretched over it. Together, they combine strength and flexibility, an ideal to which we all aspire. (The yoga of greenhouses? Never mind.) The PVC system also makes it easy to connect the arches to each other, which might be a bit of a challenge with plain rebar. Instead of a blowtorch, all we needed was a few T and X fittings.

T inserts X inserts

Grounding triangle tiesWe didn’t even use glue in the connecting pieces, since we want to be able to dismantle this structure; instead, strategically placed twine both makes glue unnecessary and adds the occasional diagonal, a key to any stable structure. Believe me, my ex-physicist husband, not I, was in charge of the strategic placement of said twine. The twine was also tied to short lengths of rebar sunken at an angle in the not-yet frozen ground.

Rebar & fence 2 One of the trickiest parts–another left strictly to Steve–was securing the rebar arches to the fence. This we achieved by fixing a metal brace to the fence, bending it over the bar, then wrapping a hose clamp over both and tightening for all we were worth. Inventive, inexpensive, and way outside the box.

Post & PVC 2 The vertical supports I insisted on were merely fence posts shoved under several intersections, to which they were secured with plumber's tape, a.k.a. metal strap. Again, very simple, very cheap.

The result is so stable it barely shudders in the highest wind, and the roof hardly gives at all under the heaviest snow load.

_________________________________________

George_Bridgetower_Y-1
George Bridgetower

George Augustus Polgreen Bridgetower (1780-1860) violinist and composer, was the son of a white woman named Ann Marie who was probably Polish and whose unmarried name may have been Sovinki, and a black man named John Frederick Bridgetower, possibly an ex-slave from the West Indies, possibly an African prince, possibly both, who was servant to a Hungarian prince. (This story is full of gaps, but it's still fascinating.) Bridgetower made his violin debut at the age of 9 or 10 and went on to perform at famous venues such as Covent Garden and before royalty throughout Europe, winning the accolades of the public and musicians alike.

Eventually, he performed the premier of Beethoven’s Violin Sonata No. 9 in A major with Beethoven at the piano. The music was so new that complete scores weren’t available, and Bridgetower had to sight read part of the sonata over Beethoven’s shoulder. Beethoven was so impressed that he planned to dedicate the sonata to Bridgetower, until they had a falling out (possibly over a woman, or over Bridgetower’s remarks about a woman) at which point Beethoven dedicated it to Kreutzer, Europe’s premier violinist, instead. Kreutzer considered it so difficult as to be unplayable, and never performed it.

Go figure.

There are articles about Bridgetower in Wikipedia, the British Library’s Online Gallery of Black Europeans, AfriClassical.com, as well as a lesson packet courtesy of the City of London Festival. Finally, there’s a lovely poem by Rita Dove, “The Bridgetower,” in The New Yorker of Nov. 24, 2008, which is what started all this.

6 Responses to Greenhouse construction

  1. I’ve never had pvc hold up for something as large as a walk-in structure. Even with bracing it bends too much in the wind or with any kind of snow load. The sunlight and heat make it brittle, and it shatters. I’d recommend using metal conduit tubing. If you get a pipe bender, or build a jig you can bend it almost as easily as the pvc, and it will hold up a lot longer.

  2. Thanks for the photos of the greenhouse. I was wondering about its construction.
    And I like your idea about adding a little post-script for black history month.

  3. Excellent account of your greenhouse construction. Really like the idea of combining the use of PVC and rebar. Great photos too. Very impressive work.

  4. Adam Waterford

    Was the greenhouse warm enough for the winter? It seems to lack proper insulation; nonetheless, the use of plastic and PVC pipes is pure genius! It’ll definitely save you a lot of money – especially for those who don’t have a clue on what to do with those leftover PVC pipes from tons of DIY projects LOL.

  5. I agree with Alan. Metal conduit tubing isn’t that expensive, either. I personally want to make sure that the roof of my green house doesn’t take the whole thing with it, when it gets blown away by a strong wind. Imagine all crops going to waste if that happens.

  6. Belated responses, but here goes:
    Alan, I agree about unsupported pvc, but I didn't want to deal with bending metal tubing, so this is pvc over rebar. Much easier to deal with than metal tubing, but far stronger than plain pvc.
    Thanks, Susan.
    And you too, Ann. But I shouldn't get the credit for the rebar/pvc combo: that's
    Eliot Coleman's idea.
    Warm enough for winter, Adam? Er, no. Coleman has pictures of himself relaxing with a cup of coffee in his in cold weather, but that's not something I'd want to do in mine in January. I keep meaning to upgrade it, but so far haven't been able to. Someday…
    So far, Brendan, the plastic eventually goes, but the framework is solid.
    –Kate

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