Friday, September 7, 2012

Build a Hoop House for Garden Greens all year Long!

Found a nice little article from the "Backwoods Home Magazine" (their website) that gives the materials needed, a diagram and some good tips regarding how to keep fresh leafy greens all year long in what this designer calls a "hoop house" which is basically a retractable greenhouse and he's from the Pacific Northwest.

 Vern Harris offers help through his email and he's willing to help with supplies and any questions you may have.

 Cover 137

Materials Needed: (pg 54 of Sept/Oct 2012 Ed. of Backwoods Home Magazine)
(3) 2x6 inch X 8-foot untreated fir
(5) 1/2 inch Schedule 40 PVC pipes, 10 ft long (cut to 9 feet)
(2) 3/4 inch Schedule 40 PVC pipes, 10 ft long
(1) 3/4 inch Schedule 40 PVC pipe, 4 ft long
(2) 3/4 inch Schedule 40 PVC 90 degree angle pieces
(10) 1x1/2 inch Schedule 40 PVC tees.
(10) 1/2 inch aluminum tubing cut in half-inch lengths
(30) Lath screws, size #8x1/2 inch (These hold the plastic cover to the PVC hoops)
(10) Wood screws #12x2 inch (to hold the rails to the wooden frame of the beds)
(1) 3/16 inch x 30 foot length of polyester clothesline
(2) 3/16 inch eye screws for attaching clothesline
(1) piece 9 x 10 foot Dura-Film Thermax plastic for the cover and one piece 4 x 10 feet for both ends.

(Taken from page 55 of Sept/Oct 2012 Ed. of Backwoods Home Magazine, Article "Build a simple DIY hoop house and you'll have fresh greens all year" by Vern Harris, author.)

"These hoop houses consist of 3/4 inch PVC pipe for the bottom rails and 1/2 inch PVC pipes for the hoops. The ends of the hoops fit into 1 inch PVC tees which glide on the rails. These hoops are covered with a professional-grade greenhouse plastic that is heavier than most hardware-store sheeting. The type of plastic I use features condensation control and is guaranteed for five years. At the bottom of each hoop is a 1 inch tee which holds the hoop on to the rail. The tees glide over the rails to open and close the greenhouses.

 The only (minor) complication was figuring out how to attach the rails to the existing raised beds and how to get the tees to glide smoothly over them. I needed some kind of support to hold the rails slightly above the wood frames of the beds, and the support had to be designed so it wouldn't interfere with the movement of the tees. The diagram shows the solution to that problem.

 I simply pre-drilled screw holes all the way through each rail, set the rails on the 1/2 inch tall pieces of aluminum tubing (to stand them away from the wooden frames of the beds), and screwed down through the rails and the aluminum into the wood. Voila! Rails attached to beds. Note that the rails extend about 18 inches beyond the beds on one end. This allows me to pull the cover completely away from the growing plants beneath. This extension should ideally be on the north side so no part of the opened hoop house ever casts shade over the bed.

Next, as you see in the diagram, I cut away the bottom of each tee and slid the tees onto the rails, five tees on each side of the bed. The 1 inch tees are a little sloppy so they can slide smoothly over the 3/4 inch pipe of the rails. With their bottoms cut away, they don't run into the aluminum supports.

Then I took five 10 foot lengths of 1/2 inch PVC pipe for the hoops, cut them down to 9 feet and pre-drilled holes to hold the plastic cover. I insterted each piece of 1/2 inch pipe into a tee on one side of the bed, then carefully bent it into an arch shape with the holes facing to the outside, then inserted the pipe into a tee on the opposite side of the bed. 

Next, I added the cover. The plastic i use is called Dura-Film Thermax. It is very good for this purpose due to its extra thickness, long life, and ability to help control condensation-which can be a real problem in greenhouses. First I cut the plastic to 9x10 feet. Then I attached it to the five hoops (using 1/2 inch lath screws, which have washer heads to help prevernt tears and leaks) so that the 9 foot dimension left a 6 inch overhand on each end and the 10 foot dimension lay over the arch to give 6 inches of extra length on each side. This extra length comes down over the raised bed frame.

I then cut two pieces of plastic, 4x5 feet, one for each end. I attached one to the hoop on the extended end of the bed using the same fasteners. The other end is not permanently attached. When the hoop house is closed you can pick i t up and clamp it to the  hoop.

Finally, I attached a length of 3/16 inch clothesline to the bottom of the front hoop on each side using 3/16 inch eye screws. These serve as pulls to slide the cover over or away from the raised bed. And that's it!

In a harsher climate than mine you could attach a second cover inside or outside for greater protection from the weather, but I've found that the single cover is enough to keep the inside of my hoop houses above freezing even on the coldest north-west days. And man, those fresh garden greens sure do taste good in January and February."

Pictures and diagrams are listed in the Backwoods Home Magazine, if you want a better idea of the hoop house design.

No comments:

Post a Comment