Things You Should Know First
Before you jump right into the instructions for how to build a poly tunnel green house, there are a few things you should know first. Here they are, broken down by greenhouse parts and supply lists. For your supply list, specific numbers and footage depends on the size greenhouse you plan to build.
What You Will Need
- 4 ft of rebar per hoop (each leg of each hoop needs a 2ft piece of rebar)
- Gray PVC pipe (3/4-1 inch in diameter)
- Greenhouse plastic
- 2x4s equal to the length of your greenhouse, times 5, plus enough to fit either end at ground level
- Staple gun
- Drill (if you prefer to pre-drill holes in the PVC)
¾ inch gray UV PVC pipe works best and withstands sun exposure longer than regular white PVC. However, ¾ to 1 inch white PVC works just as well in terms of structural integrity.
Each end of each hoop of PVC has to slip over a piece of rebar, so be sure PVC and rebar fit each other.
Ribs should not be more than three feet apart to maintain structural integrity and keep plastic from tearing, especially in snowy or heavy rain conditions.
Support strips screwed to the inside of the installed hoops at 10, 12, and 2 o’clock positions keep the hoops in place and provide a more sturdy foundation for the plastic skin. Standard 2x4s are the best option.
Each end piece of the poly tunnel is assembled separate from the main structure, and then fitted onto its rebar feet.
Framing the doors in each end piece provides wood to staple the plastic sheeting to, but is not absolutely necessary.
You will need two people to install end pieces.
Any heavy duty clear or translucent plastic will work, however, plastic specifically designed for greenhouses is best in terms of wear.
Plastic should be a continuous piece from one sidewall to the other. Seams should be parallel to hoops.
Keep plastic taut, but not too tight. Too loose, and rainwater or even a light snow can pull down the greenhouse. Too tight, and rainwater or snow will tear through the strained plastic.