How to Turn a Carport Into a Greenhouse

Sand the entire surface of the carport to remove loose splinters from wood surfaces or rust from metal. Ensure there are no loose nails, screws or other items that can damage the greenhouse covering.

Stretch the plastic greenhouse film over the top of the carport and cover two of its sides that don't have walls. Ensure the plastic film is covering the structure tightly. Place batten tape over the support beams of the carport and the plastic film and nail the plastic in place securely. Stretch a second layer of the film over the other two sides if your structure has no walls at all, or attach a sheet to cover the final side with batten tape and nails. Leave one corner unsecured so you can access the inside.

Draw a plan for your carport greenhouse and determine where you want to install plant beds to accommodate walking paths. Measure the dimensions of the spots where you would like to place beds. You can use one large bed or many small beds in your greenhouse.

Cut the untreated plywood to the size measured for your plan to serve as the base for the gardening box. Cut the untreated lumber pieces to accommodate the length and depth for your gardening bed. For example, if you want a 2-feet-by-4-feet bed, cut a piece of plywood that size, two 2-foot-long boards and two 4-foot-long boards.

Position the boards in place around your plywood base and screw them together using 3-inch wood screws, using two screws per corner. This will leave you with a 6-inch-tall rectangle or square frame.

Lift the frame and slide the plywood out from under it. Screw the plywood to the top of the frame using 1-inch wood screws. Drill 0.125-inch holes in the frame near the plywood to allow standing water to drain. Flip the gardening box over so the plywood is on the bottom.

Place cardboard or weed-blocking fabric on the ground where you plan to place the gardening bed. If you are putting the bed on cement or gravel, you can skip this step. Place the gardening bed on top of the spot.

Fill the gardening box to the top with soil. If you wish, you can create a grid system over the gardening box to allow you to differentiate between the various plants in your box. To do this, drill 1-inch screws about half way into the frame, positioning each a foot apart. Tie nylon strands to the screws to create a 1-foot by 1-foot grid over you box.

Plant plants in the bed. You may need to install supports, trellises or labels for the plants.

Repeat Steps 3 through 8 with any additional gardening beds you want to install in your greenhouse.