Why build a hoop house? As gardeners, we are always looking for ways to get a jump-start on spring planting, hoping we won’t have a late freeze. Mother Nature sometimes has her own ideas, and we are not always lucky. Finally we think it is safe and we plant out our precious seedlings. Unfortunately we are just as apt to catch the dreaded, unexpected weather forecast… and in sheer panic mode, we haul out all the extra sheets, blankets and anything else we can use to cover our plants.
With so many of us now growing a bigger garden to feed our families, we have passed the point of having enough blankets and sheets to protect all the plants in our larger gardens. Plus, some of us living in very short growing season areas are trying anything and everything to extend the season just a bit longer so our tomatoes ripen and the peppers and melons grow large enough to eat.
A late frost in spring (or an early fall frost) affects market gardeners too… local gardeners who depend on their income from farmer’s markets. They especially want to protect their crops and start their growing season early for all the customers who wait anxiously for the first real tomato since last year. There is a segment of gardeners popping up who want to do what Eliot Coleman* has been doing in Maine for 20 years (he wrote a book about it)… Four Season Harvest. To extend growing and harvesting to four seasons in northern climates like he does, you would need to read Eliot Coleman’s book for details, but I believe he uses a moveable hoop house dragged over his garden beds when it starts to get cold.
It would be lovely if we all had the money to build a 100 foot x 30 foot high-tunnel greenhouse/season-extender, with fancy roll-up sides for summer ventilation. Better yet, a heated greenhouse! However, few of us can afford to do that in today’s economy. So why not build an inexpensive hoop house?
In mid-March this year (2008) I had the opportunity to participate in building a low-cost 100’ x 13’ hoop house with some volunteers at Appalachian Sustainable Development in Abingdon, VA. This hoop house is primarily designed to extend the growing season here (zones 5-6) by a month or so on each end. However, it is easily adapted to withstand colder temperatures, which I will address later in this article.
Anthony Flaccavento is the Executive Director of ASD, and a market grower. A bunch of us assembled on a March Sunday afternoon at his farm… with dark threatening clouds and brisk cold winds assaulting us out in the open field. Nevertheless, about a dozen of us erected this hoop house in less than 2 hours. Since this was a low budget project, it could only be kept within the budget with volunteer help.
Tony had prepared a section of the field with beds earlier, since the interior width of this hoop house (13’) wouldn’t allow his large tractor anywhere inside except down the middle. He had prepared 3 rows ready for planting, covered with black plastic to help warm the soil. The first thing we did was measure 100’ and run a string line down each long side so we had a straight line. Then the men, using a sledge, hammered in the 3’ fiberglass pipes (ground pipes) along the line at 10’ intervals, driving the pipes roughly halfway into the dirt. These pipes would hold our hoops so they were canted slightly inward, along the imaginary line the hoops would follow. The fiberglass pipes had originally been manufactured for ax or sledgehammer handles, then became surplus. Tony bought them for 50¢ each and we used a total of 20.
Ground Pole fits into PVC pipe
Ground Pole in bell-end of PVC pipe
PVC over ground pole in place
Once the pipes were driven on place, we began placing the hoops. They were 20’ long, 1-1/4” PVC pipes with one bell end. We slipped one end over a pipe and the PVC swung wildly in the air like those foam bats kids use in swimming pools. It was quite comical to see a dozen or so adults, most of us past our prime, trying to control 20 feet of PVC swaying crazily above our heads in strong winds. Finally though, we were able to capture the loose ends and slip the bell end over the opposing pipe.
Next was placing the frost cloth aka row cover. The fabric was unrolled down the 100’ length, with an extra 10’ or so at each end (to close off the ends). Then several people stationed themselves along each long side and started dragging the fabric across the top of the hoops and down the far side. Trust me, this is not a 2-person job. In calm weather, I’d suggest at least 4 sets of hands for the job. While most of us kept a firm grip on the fabric, a few men went down the first long side and anchored about a foot or more of fabric under a mound of dirt running the entire length.
20' PVC pipes in the wind
Hoops all anchored
Fabric (Row Cover) being stretched & tightened
After that, we all pulled the fabric tight while the dirt was mounded down the second long side. The far end “wall” was pulled tight and fastened in the same manner. The near end was merely pulled into a flap for access that Tony taped together. All that remained was to go inside (thankfully out of the cold wind!) and align the hoops somewhat parallel. These hoops could have been fastened together via a long series of PVC down the center but Tony hadn’t done that in his previous hoop house and it had worked just fine for him. He also said that when it became hot in summer, he would remove the fabric (but not the hoops) and store it until fall, when he would reapply it over the hoops to gain some extra fall growing time.
PVC (20’ x 1-1/4”) $12.29 each from a plumbing supply. Needed 10. Total $122.90. Fiberglass ground posts (handles) 3’ long, 50¢ each, needed 20, Total $10.00. Row cover 20’ x 120’, 1 oz*., 120’, Berry Hill $114.00 includes shipping although there is an advertised $150 minimum order. You might look for off-season specials. Total Cost: $282.90
*Note: the weight is per square yard of row cover fabric.
Berry Hill’s 1 oz. row cover (like we used) transmits 70% of the available light and protects down to 24ºF. To protect from cold a bit more, they offer Medium Row Cover, 1.2 oz. with 60% light transmission, good down to 22ºF. Or you could go for Heavy Row Cover, 1.5 oz, 50% light transmission, good to 20ºF.
I don’t really need a 100’ hoop house, but a 30’-50’ one would be very useful to extend my growing season. Using this type of construction, it can be affordable! Perhaps my neighbors and I can split the minimum fabric cost and share the labor.
I have a 'growing my own food' obsession that comes from my overlapping interests in cooking, nutrition and gardening. I am also a "teacher", a writer, a builder… and a craftsperson and... and… and many other things, LOL. In fact, I guess I am a generalist, and a Seeker.
I live in the southern Appalachian Mountains on a hillside with a creek in front, and drive a 15 year old truck I lovingly call “My Farmer’s Ferrari.”