Call it what you will, an extra three months of growing season in Northern Nevada would be cool
Let me tell you right up front, if you’re smarter than the average editor, if you’re not afraid to experiment a bit, if you’re able to follow a project through to its finish, and if you’ve got a pair of relatively windless weekends, you can build a hoophouse. And if you build said hoophouse, you can add, at minimum, three months to your veggie-growing season. If you live in Reno, that may give you an eight-month growing season. And that’s just for the cold-sensitive stuff like tomatoes and peppers. I’m willing to bet my leafies are going to go all year. We’ll see. I’m not afraid.
Also, let me place near the top the fact that the instructions for building a low-cost high tunnel (hoophouse) can be found on Utah State University Cooperative Extension’s website. Just go to the web site. I based my design upon this one, so all my mistakes and variations are also based on it.
If it sounds like I’ve been talking gobbledeegook up to this point, it’s like this: A hoophouse is basically a semi-permanent greenhouse made out of 6 mil clear plastic, 1-inch PVC tubing, and 2-by-4s.
Error No. 1: I paid for lumber. Use used 2-by-4s. You might try Reno Freecycle, http://groups.freecycle.org/RenoFreecycle .
My first deviation from the Utah State design was that my hoophouse is 12 feet by 12 feet. I built it over my existing raised bed garden, and my fear was that the smaller size—the Utah State design is up to 140 feet long—would have a low surface area to volume ratio, which would allow the garden to freeze when the temperature was freezing. Not so, at least not so far. I planted a tomato in the first week of April, and when the temperature on the wall of my hoophouse dropped down to 29.7 Fahrenheit, my little practice tomato didn’t even wilt. (Take that, snow on Peavine!) My belief is that the insulation provided by the six feet of warm air was enough to keep the soil from freezing. Either that, or it was magic.
Anyway, there were eight pieces of 2-by-4 that were 6 feet in length. Six of them were for the door and frame on the front, two were for the back frame. For the 12-foot bottoms of my front and rear frame, I cobbled together 2 6-footers. No reason at all for new lumber.
Error No. 2: T-posts are part of the design.
Here’s construction in a nutshell. Take your 2-foot lengths of half-inch rebar. Starting in a corner, pound one 18 inches into the ground, move three feet over, pound another in—every three feet. Then do the same for the opposing side. Works out great for a 12-by-12 hoophouse. Then join two 12-feet lengths of 1-inch PVC, which you’ll find in the plumbing section of local Carter Brothers Ace Hardware (or to be honest, chains Home Depot or Lowe’s) and slip each end over a piece of rebar. Do this for each pair of rebars. Tie a long enough center “rib” across the top, and you’ll have the basic shape. You can always cut or add tubing to get the right height and width.
Then the front and back need frames. The front needs a door. I made the mistake of trying to make a 4-foot wide door, which is stupid for a 12-foot wide frame. I have a fence three feet outside my garden, so the door wouldn’t open all the way. I ended up cutting the door in half vertically and hinging both sides. It’s heavier, but at least I can open it all the way to carry in bags of manure. My dumbest error was trying to incorporate my existing steel bean trellises into the rear of the tunnel rather than building another frame out of 2-by-fours. The fact that there was nothing to staple the plastic to became a problem, and I ended up having to take the back half apart and rebuilding it.
I couldn’t figure out why the front and back were so wobbly. Well, T-posts are supposed to be pounded into the ground, with the front and rear frames attached to them. You may be able to find where that’s mentioned in the instructions, but I couldn’t. At least it did mention buying them.
Error No. 3: Six mil plastic doesn’t stretch, but it does tear.
I tried to be cute with my 20-feet-wide sheet of plastic, cutting a strip that I thought would save me a few cents by cutting it exact, but it’s smarter to just measure it long and to cut a few feet off when it’s stapled in place.
One thing I did that was an extra expense but worked out handily was, since my hoophouse was built over a raised-bed garden, to put eyehooks in the bed itself for tying down the rope that holds the plastic sheeting over the PVC hoops.
Stuff I learned
The total cost for this thing was less than $200, and $80 of that was for the plastic, which had five times as much as I need for any single year. I believe this plastic should last three years, so I have about 15 years worth of plastic.
Part of the reason I grow vegetables is because I like to watch them grow. The hoop house isn’t beautiful by any means, so I think it’s important that it’s easy to tear down on, say, June 1 and rebuild on Oct. 1. For that reason, I didn’t glue together the PVC tubes. Portability requires the front and rear frames be solidly constructed, and plastic sheeting securely fastened to them. I’m going to leave the T-posts in the ground, and cut the plastic so that the frames are solid, but moveable, units. I’ll rewrap and restaple the main roof to the frames in October. Another thing to remember is, it gets hot in there; Earth Day reached 81 degrees. It was 105 in my hoophouse. Steve Litsinger of Churchill Butte Organics warned me at the Earth Day celebration that now’s the time that plants can be overheated, so removable vents must be made in the frame, and shade cloth should be handy.