I visited a neighbor today. While driving by I noticed the skeleton of a hoop house in his back yard. I left a note asking if it was for sale. A couple of days later he sent me a text. It was not for sale but he would be glad to show me what he did to build it.
He was a friendly and helpful guy and was delighted to have somebody to show his handy work to. He had used 1-1/2" diameter, Schedule 40 PVC pipe for structural elements which made it a non-starter in my book. The hoops were on 4' centers and he had three longitudinal stringers to keep them from splaying. The footprint was approximately 18' by 40' and according to his records it cost him just a little over $1 per square-foot to build eight years ago.
His primary purpose is to supply "greens" through the winter: Lettuce and green onions for salads, Asian greens for stir-fry and kale and chard for hot greens and to add to soup.
One interesting feature was that he had a second hoop-house inside the big house for the coldest part of winter. A single layer of plastic loses a lot of heat over night and can freeze the tops of lettuce to mush. Some of the other growers he knows run a double-layer of plastic and then "blow" air between the two layers with something like a the vent on a shop-vac to inflate them.
Sifting through the conversation, some of the biggest challenges include:- Temperature regulation, especially when it is sunny
- Storage for water, fertilizer, trays, soil
- Weeds
- Wood decay
His small farm was tidy and neat and I enjoyed listening to him talk about growing food.
Why is the PVC pipe a "non-starter"? ---ken
ReplyDeleteProbably because I am biased against using PVC for structural elements. PVC is good for absorbing vibration and has decent UV resistance but it can be brittle and its mechanical properties are not very impressive and it sags over time.
DeleteHave you ever seen a gunstock that was molded of PVC or a factory-made piece of furniture that was made of PVC? PVC is for shower curtains and water pipes and siding.
We built a small (8' wide x 12' base) hoop house, using 1" PVC slid into galv. plumbing pipe inserted into ground. Iirc, five ribs with three stringers. The covering was plastic construction fence (ugly orange you see at construction sites) for removing cats from using the tilled earth for use, as well as providing some sun cover from baking the tomato plants. One other benefit - the many holes in material prevented the cover from high wind damage and is naturally UV resistant to boot. We don't have any snowfall in south Texas so pretty unlikely the PVC would survive inches of snowfall. But for some applications such as ours - not bad.
DeleteI also use PVC as sheaths for knives and machetes, heating with a heat gun and pressing flat. Cut an end longitudinally about 6" and then out, and fold the tab in middle for a belt hanging loop that slides over belt.
My husband built a small greenhouse from old windows he got for free when a relative rebuilt their old porch. He used 2x3 or 2x4 to make the frame. It was cheap and worked well. Windows could slide open to allow ventilation through the screens that were on the window tracks.
ReplyDeleteDownside is no insulation, so plants could not be left outside on cool nights. There was no foundation or slab, so chipmunks and mice were in there, but never seemed to damage any plants. Plant trays were set on pvc or plastic tubing shelves. We used the top shelf, about 3 ft off the ground for plants, and the lower shelves for tools.
The roof was also made of windows, so my job was to rake the snow off it, gently, after each storm. As constructed, it would not support much of a snow load.
We’re still using it, some 10 yrs later.
Southern NH
Correction: the shelving is light aluminum, I believe. The shelf racks are wire. These came from an old plastic greenhouse we had.
DeleteSNH
Using a cover over plants inside a greenhouse I first saw used by Eliot Coleman in his book, "Four Season Harvest".
ReplyDeleteI have seen bubble wrap as insulation on the inside of a greenhouse. Don't know how it was stuck to the glass.
ReplyDeleteUsually a spray of water suffices for the bubble wrap. I did this when an unheated enclosed porch doubled as an extra bedroom during a college winter.
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