Farmers and gardeners were using temporary greenhouses long before the advent of polyvinyl greenhouse plastic made it possible to erect a greenhouse in short periods of time. These small cold and hot frames were typically made by placing a glass window over a wooden box or lowering a clear glass bell over a plant to create a warm environment where seedlings could harden off in preparation for being planted in the ground. Today, you can erect temporary greenhouses in less than a day thanks to the flexibility of available materials.
Select a location for your greenhouse that receives full sunlight for at least 6 hours a day.
Pound one length of ¾-inch rebar 1 foot into the ground using a rubber mallet. Arrange six rebar lengths for each side of the greenhouse. Space the rebar evenly over the length of the greenhouse. Each of the six pieces of rebar should align with the pieces on the opposite side of the greenhouse.
Slip the conduit pipes over the rebar stakes on one side of the greenhouse. Flex each pipe into an arch and place the other end over the pipe on the opposite side.
Stretch a piece of 9-gauge wire across the high point of the tunnel of arches to create a ridge. Use a ladder to reach the top of the arch tunnel. Wrap each piece of pipe with the wire. This will increase the stability of the greenhouse.
Drape the PVC tunnel with polyvinyl plastic sheeting. Weigh down the edges of the sheeting with cinder blocks to hold the sheeting in place.
To remove the temporary greenhouse, set aside the blocks and pull the sheeting free from the frame. Then unwire the pipes and pull them off of the stakes. Lastly, pull the stakes free from the ground.