Anyone can build a portable greenhouse with basic tools and readily available products. A portable greenhouse is a great way to extend your growing season by getting an early start at planting your vegetable crops. And when the weather cools off, you can still grow crops in your greenhouse. With a basic heat source in the winter, your greenhouse can be in full use, providing fresh herbs, many types of vegetables and flowers.
Find a spot as flat and level as possible or with a very slight incline to prevent water accumulating in your greenhouse. Make sure that the spot is in full sunlight with no trees nearby. Tree branches can rub or even break and fall on your greenhouse.
Assemble the King Canopy frame according to the manufacturer's specification. Secure frame-tube connections by wrapping the joints with duct tape.
Square the frame of the canopy so that it stands straight. Use your tape measure to check that the distances from corner to corner measured diagonally are the same. This will ensure your frame is square.
Place a T post vertically flush with one of the corner legs of the canopy frame. Make sure that you place the T post on the inside of the canopy. Drive the T post at least one foot deep into the ground using a small sledge hammer, keeping the T post straight and flush with the canopy leg. Secure the frame to the T post by wrapping them together tightly with duct tape. Repeat this process to secure all the vertical legs of the canopy using the other T-posts.
Attach the lashing straps, spreading them evenly across the length of the canopy roof's center beam. Overlap the lashing straps on the horizontal top wall supports of the frame and tighten them, keeping the ratchet piece on the strap (the metal fastener on the lashing strap used for tightening) facing the inside of the greenhouse.
Cut a piece of the hollow pool noodle that is slightly longer than the ratchet attachment on the lashing straps. Place the pool noodle over the ratchet and secure it with strapping tape. This will prevent sharp edges from rubbing and possibly tearing the plastic roof cover. Repeat for all straps. Tighten all straps firmly and evenly without applying too much force that could twist the frame. Check that the frame looks square and even.
Cut two pieces of your 6-mil plastic so that each piece measures 20 feet by 30 feet. Overlap the 30-foot lengths by 2 inches and secure them with the strapping tape along the full 30-foot length. Overlap the first tape joint by one-half inch on the full 30-foot length. Flip your plastic cover over and repeat the taping process on the other side. This will secure and reinforce the plastic canopy cover.
Pull your plastic roof over the top of the canopy using a ladder. Stretch the plastic cover evenly, so that it has an even overlap at the point where it is in contact with the ground along the length of the frame. Check that the cover will also cover both ends and overlap on the ground evenly.
Secure the overlapping parts of the greenhouse cover in contact with the ground by placing rocks, bricks or patio stepping stones. Use the metal spring clamps to secure the plastic cover to the frame wherever needed.
Move your portable greenhouse to a new location simply by removing the T-posts. When you set the greenhouse in the new location, replace the T-posts at that site by following the instructions again in Step 4.