For our garden, we chose to have a 4.5-foot-by 41-inch 34” tall season extension added to the north garden bed. We chose this garden bed because crops in the south garden bed were still producing vegetables. While the north garden bed is 4-feet-by-8-feet, we chose to make the season extension approximately 4.5-feet-by 41-inches because the Brussels sprouts were occupying the rest of the garden bed.

Materials Needed for Building the Wooden Frame


Materials Needed for Building the PVC Frame and Dome

DOME TOTAL: $13.23

Hardware Needed for Building the Season Extension



Tools Needed for Construction

  • Tape Measure
  • Drill
  • Drill bits and drivers for screws
  • Saw to cut wood (circular, miter or handsaw)
  • Hack saw to cut PVC
  • Rubber mallet
  • Scissors


Watch the video to see how steps 1-11 are completed.

Watch the video to see how steps 13-15 are completed.

Watch the video to see how steps 16 and 17 are completed.

  1. Remove the fence panels from the garden bed. Measure the interior of your garden bed where you will place the season extension.
  2. Using those measurements, you will determine the size of the season extension. We chose to have a 4.5-foot-by 41-inch 34” tall season extension. Lay out the wood and PVC.
  3. Starting with the wood, cut one 51” piece from one of the 2x4x8 cedar boards; this piece will be the front frame of the season extension. Then cut two 41” pieces from the other 2x4x8 cedar boards; these two boards will serve as the sides of the season extension. For the rear piece of wood, we used a 4x4x8 because it will be bearing more weight than the front piece. Cut the 4x4x8 board into one 51” piece. Using 3” screws and a drill connect the four cedar boards together to make the frame.
  4. Take the 1” PVC. Cut four 8” pieces from the 3 linear feet 1” PVC; these will be the sleeves to hold the arched pieces of the season extension together. Place one 3/4” plug in each 8” piece of PVC.
  5. With the 3/4” plug facing down, place the four 8” pieces in each corner of the wooden frame. Now you want to attach each of them to the wooden frame. Using the 1” galvanized pipe straps attach one to bottom and one top of each four 8” piece with 1 1/4” exterior screws.
  6. Take the 1/2” PVC. Cut two 98” pieces from the 33 linear feet; these will be the curved pieces that form the arch to hold up the agribon. Then cut two 36” pieces; these will be the sides of the PVC frame. Cut one 51” piece for the rear of the PVC frame. Cut three 22” pieces; two of these pieces will make the front of the PVC frame. The remaining 22” piece will be placed inside the frame.
  7. Place the 51” piece on top of the 4x4x8. Using a 1/2” elbow at both ends of the 51” PVC piece attach the two 36” pieces. Attach a 1/2” elbow to each 36” piece, and then attach one 22” piece to each of those elbows. There will be a gap between the two 22” pieces. Later, a handle will be added between this gap, which will allow you to easily open and close the season extension.
  8. Be sure all of the PVC pieces are securely attached to each other. Starting with the rear PVC piece add a snap clamp next to each elbow. Add snap clamps on either side of the elbows on the remaining PVC pieces. On the front PVC pieces, add a snap clamp to the ends that will be next to the handle.
  9. To secure the PVC to the wooden frame, you will use 16 1/2” galvanized pipe straps. You will need to bend one side of each pipe strap so it secures the PVC to the wooden frame on top of the frame and on the inside of the frame. Beginning with the rear PVC piece, place a 1/2” galvanized pipe strap next to a snap clamp. Using 1 1/4” exterior screws, screw the pipe strap to the wooden frame. Attach another pipe strap next to the other snap clamp on the rear piece. Attach the remaining PVC pieces to the wooden frame by adding pipe straps next to the already attached snap clamps. You will need to use a minimum of 18 snap clamps, but the more you use the better. We used 26 snap clamps; 6 on the rear PVC piece, 5 on the left side, 4 on the right side, 2 on each front piece, one on the interior front piece, and 2 on each arch.
  10. The remaining 22” PVC piece will be placed on the interior of the season extension below where the handle will be placed. Attach the PVC piece using two 1/2” galvanized pipe straps and 1 1/4” exterior screw.
  11. Place the zinc coated handle between the two 22” pieces and attach the handle using screws provided.
  12. Take one of the 98” pieces of PVC. Place it in one of the corner sleeves. Bend the PVC and place the other end in the corner sleeve that is diagonally across. Take the other 98” piece of PVC and place it in the remaining sleeves.
  13. With the wooden frame completed, place it in the garden bed. When you add the season extension to your garden, you want the top of wooden frame to be flush with the top of your garden bed. In order to do this, you may have to dig out some soil beneath the season extension. Rather than dig four inches of soil out to make the season extension flush with the our garden bed, we dug out two inches of soil and attached a 54” 2x4x8 to the top of our garden bed using 3” screws. This raised the height of the garden bed to match the season extension.
  14. Place three galvanized hinges on top of the 2x4x8 that was added to the garden bed. Position the hinges so two are at the edges of the board and one is in the middle. Ideally, try to space the hinges so they are equidistant from each other. Attach the hinges using screws that are provided to the 2x4x8 board and to the rear of season extension.
  15. Lift up the garden bed to test the hinges and to see where the season extension will line up with the existing fence post of the garden bed. Since our garden fences used hooks and eyes that allowed us to easily attach and remove our fence panels, we attached an eye to our season extension. This allows us to using the existing hook on the fence post to keep our season extension open. If your garden fence/posts do not have hooks and eyes, you can use a board to prop up the season extension while you work.
  16. Close the season extension. Remove the snap clamps from the PVC pieces. Place the agribon cloth (we used an approximately 7-foot-long by 8-footlong piece of cloth) over the arched PVC pieces. Starting at the front of the season extension, gather the agribon so it extends 4” past the PVC frame. Fold the extra 4” of agribon two to three times and then attach it to the PVC using the snap clamps. Use caution when adjusting the agribon and adding the snap clamps because the cloth can tear easily. Repeat this process on the remaining three sides of the season extension, cutting the excess agribon cloth as needed. Make sure the agribon is pulled taut to keep the season extension sealed.
  17. Once all of the snap clamps are attached to the PVC frame, add additional snap clamps to to the arched PVC pieces. 
  18. Later in the season, we will add plastic over the agribon to protect our crops. We don’t want to add the plastic now because it would cause the temperature inside the season extension to be too warm.