Johnny's Quick Hoops™ Gothic High Tunnel & DIY Seedling Heat Mat
After a season of spending countless hours in 2016 driving to and from our tiny greenhouse located on family-owned property in Dartmouth, MA, we decided it was time to invest in a new heated space. With limited funds available after buying all of the necessary seeds, supplies, & amendments for our 2017 season, we were open to exploring any cost effective method to starting our transplants. I was introduced to the Quick Hoops™ Gothic High Tunnel system designed by Eliot Coleman with help from Johnny's Selected Seeds at the Young Farmer's Conference held at Stone Barns in NY. I was immediately drawn to the simple design that used supplies available at any local hardware store, eliminating the high cost of shipping usually associated with such projects. As we researched the possibility of using this system to create a new greenhouse, we found it to be a great fit for a temporary greenhouse that could be used in our fields for season extension after all of our transplanting is complete. We decided to build two modules for a greenhouse that is 14'x32'
It is helpful to gather all tools and supplies before you start, here's a list of what tools we used:
-Electric cordless drills (having 2 was very helpful)
-5/16'' drill bit
-1/8'' drill bit
-Ratchet set ( 1/2'' )
-Clamps (at least 6 are helpful)
-Phillips head driver bit
-5/16'' hex head driver bit
First, we placed our orders with many different purveyors in order to save money on supplies. We used the calculator to figure out exactly what supplies we needed and brought them out to the farm. There was still a good 12 inches of snow on the ground when we started but luckily the weather warmed up for most of the time we were building.
We spent the first day measuring, cutting, and pre-drilling all the pieces to make assembly quicker. We would suggest that you read the whole instruction set before beginning because some of the instructions are a little out of order and you could save time by crimping and measuring/cutting everything at the beginning. We started by setting up the bending jigs from Johnny's and bent all of our side hoops and peak sections. For the side hoops, we found it best to slide the 1 3/8'' top rail through the side hoop bender a foot or so at a time and bend it bit by bit for a smoother, straighter bend. We lag bolted it to a stack of very large, heavy pallets and had one person bending and one person receiving the pipe to keep it from corkscrewing. Make sure whatever you bolt the bender to is heavy enough to not move.
Timelapse of bending the peak sections and side bows:
By the day's end, we had bent the side hoops and peaks, measured and cut the rail for the bottom rails and ridge pole, and crimped the ends of the 3/4'' EMT for the cross bars.
I apparently did not get any photos of us setting up the jig to assemble the bows, but it is pretty self explanatory if you follow the instruction manual. We found it helpful to make sure the measurement from the top of the peak to the brace bands was equal on both sides to make sure the collar tie was straight. Pre-drilling through the brace bands was very necessary so keep that in mind.
After the bows were assembled, we lined up the bottom rails and measured the distance between corners to square the base. We then got them standing by inserting them into the T clamps along the bottom rails. It is helpful here to read a few steps ahead and to slide on the brace bands in preparation for the corner braces, knee rails, and end wall angle braces. You can save some work by ordering a few extra T clamps for the knee rails instead of brace bands so you can avoid crimping and drilling the ends.
For the ridge pole, we followed the directions and lined it up with the bows to figure out where to pre-drill. We would suggest drilling all the way through with the 5/16'' bit and then reaming out the top hole with a slightly larger drill bit to accommodate for the square shape under the head of the bolt. We were worried that if the head of the bolt stuck up above the peak that it could catch on the plastic when we were covering it.
After the ridge pole was up, we put on the corner angle braces and started on the second module.