Above is all the materials you will need to make the frame, Total cost for these materials was about $17 cdn not including plastic. Materials include:
- (4) 1/2"x10' pvc electrical conduit
- (3) 1"x2"x8' lumber
- (4) 2 1/2" bolts and nuts
- (4) washers
To build the tunnel start by placing one end of the conduit in the ground 12-18" deep and then bend the other end down placing it 12-18" deep as well. My bed is narrow so I ended up with a tall tunnel but it will also fit a bed 36"-48" wide. Continue placing the conduit, evenly spaced up to 8' long. With all the conduit in, cut one 1x2 to the length of the tunnel and fasten it in place.
Fasten the 1x2 in place by drilling a hole through the conduit into the 1x2. Then place your bolt through the hole and tighten everything in place with the washer & nut.
The top 1x2 will lock all the conduit into each other and will stop snow/rain from pooling on top. Now the only weakness is the tunnel will sway from wind and snow pressure. I solved this problem by cutting the other two 1x2's into stakes that were 12" higher then the tunnel.
These two stakes were then driven into the ground on either end to correspond with the top 1x2 brace. Once firmly in the ground I pre-drilled into the top 1x2 and added two screws to fasten everything together. Now you will have a frame that will survive high winds and heavy accumulations of snow.
With the frame all done I placed the plastic on the frame leaving about 6" extra on each side. I weighted down the plastic with heavy rocks and also buried the back edge with soil to further weight it down. The front edge I want to have easy access to so currently I have just tucked the plastic down. Before the weather turns bad I will be picking up either Greenhouse clips or binder clips to hold the front plastic in place.
Now for what will be in the tunnel:
Chard. The empty spot behind will be for overwintering potted perennials. Come
spring the perennials will come out and I can use the space to harden off seedlings.
A lone tatsoi, get growing tatsoi!
And the main reason for the tunnel, my late planted leeks. As long as
they overwinter they should be ready for harvest some time next spring.