Now that you’ve learned how to build your own raised beds, here’s how to turn your raised bed into a greenhouse! Creating a semi-permanent greenhouse can increase your garden yield and stretch your growing season a few more precious weeks. The best part of these is, once summer heats up and your plants are well established, you can remove the plastic sheeting. When the weather turns colder, simply roll it back over your frame and ‘Voila!’, your greenhouse is back in business! The frame of your house may also be used to help support some of your vining buddies like tomatoes, cucumbers and squash.
How to Turn Your Raised Bed into a Greenhouse:
Think About Your Shape and Size
Greenhouses come in several different shapes and sizes. Depending on your motivation and power tool skills, they can be bought in a kit or built from scratch. At my house, we opted for the ‘convert the raised beds into a lean-to style greenhouse’ option using 1 inch x 2 inch lath board and 6 mil clear plastic sheeting. Both are readily found at any hardware store. While this project may seem daunting, it’s really quite easy once you get the hang of it. When you see your results, like my magical rhubarb that was 5 ft. tall by the first of May, you’ll be happy you gave it a go!
Which Direction Does the Sun Shine From?
Another consideration for placing your greenhouse is where the sun shines. A really great tool is found here. This site lets you type in your address to see exactly where the suns rays hit your property any time of day, any day of the year! It really helps in choosing the best location for your boxes, and what you’re going to grow in them.
- Existing 4ft. x 2ft. raised garden bed
- 6 mil plastic sheeting cut to size:
- 1 piece @ 5 ft. x 10 ft.
- 2 pieces @ 4 ft. x 3 ft.
- 10 pieces of 8 ft. long 1″ x 2″ lath board cut as follows (there may be some left over, 10 pieces gives plenty of room for error)
- 6 @ 4 ft.
- 2 @ 3 ft. 6 inches
- 2 @ 3 ft.
- 3 @ 2 ft.
- 6 @ 2 ft. and 2 @ 3 ft. for securing plastic to the sides of your greenhouse – these don’t have to be exact but can be made up of scraps if you have them!
- 26 @ 1 5/8″ deck screws or 22 galvanized nails of corresponding length; screws are recommended
- Screw gun with proper screw tip or hammer if using nails
- Tape measure and saw if the boards aren’t pre-cut
- Shears or razor knife for cutting plastic
Step #1: Place your corner stakes. This structure is going to end up looking like a lean-to with one side of the roof being 6 inches lower than the other; this allows it to shed rain so that the roof won’t collapse. To set this up, you will make two stakes out of the 1 x2 lath board that are 3.5 ft. tall and two that are 3 ft. tall. Take one of the 3.5 ft. tall stakes and set it in one corner of your box so that the bottom 6 inches are below the top edge of the box. You will then take your screw gun and 2 of the 1 5/8 inch screws to secure your first post snugly into the corner. Repeat with the second 3.5 ft. stake on the opposite corner of the 4 ft side of the box. Following the same procedure on the opposite side, set your two 3 ft. stakes. If you already have dirt in your boxes, you can use a hammer to pound the stakes in to the correct height and secure with your screws.
Step #2: Build the roof. On the ground, lay out two 4 ft. pieces of 1 x 2 about two feet apart. Take one of your 2 ft. pieces and set it at a right angle to one of the 4 ft. boards, overlapping the 4 ft. end over the 2 ft., and attach with one screw. Attach the other 4 ft. board to the opposite end of the 2 ft. piece in the same way. Repeat with the second 2 ft. board 12 inches from the first and the third board at the opposite end. You will end up with a frame that looks like a short ladder.
Step #3: Secure the roof. With a helper, or prop, position the roof so that your corner stakes fit just inside the outside corners. You may have to bend the pieces just a little, but it won’t hurt anything, I promise! You can then attach the roof with one screw on each corner.
Step #4: Sealing the short sides of your greenhouse. Take one piece of 6 mil plastic that is 4′ x 3′ and hold it so that it overlaps all four sides by about 6 inches. Wrap the top over the angle of the roof and, while holding it in place, use a piece of 2 ft. lath to clamp the plastic in place. Use two screws to fix the two boards together, this will hold your plastic sheeting in place without tearing it. Repeat with appropriate sized lath board on the two uprights, making sure to keep the plastic tight. For the bottom edge, you can screw your clamp to the top lip of your box. Repeat on the other side.
*Note: The clamps can be any scraps of 1 x 2 you have lying around, or you can cut them to an exact length. What matters is that the plastic is secured so that it won’t rip.
Step #5: Making the cover for the roof and long sides. To make the roof cover, spread out your remaining piece of 5ft. x 10 ft. 6 mil plastic. You will take two of your remaining 4 ft. long lath boards centered on the 5 ft. wide edge of the plastic. Placing one on the top and one on the bottom, you will then screw them together using three screws. Repeat on the other 5 ft. edge. Now you should have a 5 ft. x 10 ft. tarp with wood on either end. You will be able to roll the plastic into a cylinder.
To cover your box, simply unroll the plastic up one side, over the top and down the other. The wooden ends will act as weights to hold the plastic in place. The sides should overlap the edges of your box by 6 inches, which helps keep them sealed. If you feel inclined, or there’s a massive storm heading your way, pull the long edges tight and, using a 2 inch screw, attach them to your box bed. This will ‘batten down the hatches’ until danger is past!
Step #6: Pat yourself on the back for being a gardening pro. Now you’ve done it! You’ve converted your raised bed into a greenhouse!! If you want, you can leave it all summer, rolling up the top when it gets too hot and putting it back when you need extra protection from the elements. And, because you used screws, it’s a cinch to unzip the sides or even take the whole thing down for storage until next season!