DIY Greenhouses for Raised Garden Beds | The Interior Frugalista: DIY Greenhouses for Raised Garden Beds

May 26, 2014

DIY Greenhouses for Raised Garden Beds

I live in a Plant Hardiness Zone 3 which doesn't give us a long growing season.   To make matters worse our yard faces north and we live in a mature neighborhood with lots of trees which = shade.  Getting a high yielding crop of tomatoes, cucumbers, and zucchini has been a challenge, especially trying to grow them organically.

I decided a small greenhouse might do the trick but soon learned they are not cheap!  Unable to justify the expense I've been looking for a simple and less expensive alternative.  At long last the answer I was looking for appeared on Pinterest recently in the form of small DIY Greenhouses for Raised Garden Beds.

Small Raised Garden Greenhouses

Our inspiration came from Stephanie at Swing N Cocoa who came up with a brilliant design. 

Last weekend we took advantage of it being a long weekend and got to work building one for each of our three raised garden beds.  We modified ours somewhat from the original design but more on that further down in this post.

Materials List (for each greenhouse based on 4' x 6' beds)
  • 3 each 2 x 2 x 8 lumber
  • 5 each 10' PVC pipe 
  • 8 pipe clamps
  • wire mesh
  • 2 hinges
  • 1 handle
  • 4 each 3-sided metal corner brackets
  • galvanized screws
  • light chain
  • 6 mil roll of poly
Mini Greenhouses for raised garden beds 2 x 2 frame

Cut the 2 x 2's at 45° angles the same length as your raised gardens.  Drill a pilot hole into each joint to avoid splitting when screwing them together.

Mini greenhouses for raised beds 2 x 2 frame

Apply carpenters glue and drill a screw into each pilot hole to secure the joints.

Mini Greenhouses for raised beds frames

Attach 3-sided corner brackets for extra support (sorry we forgot to take close up pictures).  This is important considering the greenhouses will frequently be lifted up an down.

Mini Greenhouses for Raised Beds pipe clamps

Secure pipe clamps along the inside of the frame on each side to support the PVC pipe. Ensure the distance between each pipe is measured equally. We purchased 1/2" PVC pipe in 10' pieces and cut them down to 8'.  Insert the PVC pipe into the clamps and tighten the screws to hold them securely in place.

Mini Greenhouse for Raised Beds PVC Frane

Find your center.

Mini greenhouses for small beds PVC supports

Now this is where the 2' pieces of PVC pipe that you cut off come into play.

Mini Greenhouses for raised beds securing frame with electrical tape

Secure the 2' pieces of PVC pipe along the center of the top using white electrical tape.  This will stop the pipe from moving around and add support for the poly.  Another more costly option for joining the pipe is using PVC Tee Fittings and Couplings.  

Mini Greenhouses for raised beds top supports

In the original design you would secure wire mesh over top the PVC.  We purchased the wire mesh but got so frustrated, let alone sustained a few flesh wounds, and decided to come up with Plan B.
UPDATE June 12th:  We've had a lot of rain and noticed it tends to pool on the top so we've learned that the wire mesh has it's purpose and is worth sustaining some flesh wounds.  You only need to install it along the curved portion.

Mini greenhouses for small beds side supports

To add more stability to the sides we attached more strips of 2' PVC pipe just where the sides start to curve. Take a measurement from the base so they all line up perfectly.

Mini greenhouses for raised beds with poly

Here is where having some upholstery knowledge comes in handy!
Cut the poly large enough that it covers the fronts as well.  Starting on the sides attach the poly to the bottom of the 2 x 2's with staples - starting in the center.  Move to the opposite side and pull the poly tight enough that it removes any dimples in the plastic but not so tight that it distorts the shape of the PVC.

Now you can deal with the fronts a couple of ways.  Option A: Start in the center and fold the plastic to form pleats and staple them in place along the bottom of the frame.  We tried this technique but didn't like the look.

Option B: Pull the plastic taut and starting in the center staple it onto the frame. Using a nurses fold (like making a bed) fold the fabric taut to the sides and staple it down onto the frame. This is the option we preferred.  With an x-acto knife remove the excess plastic along the bottom of the frame.
Update June 12th:  Debris accumulates in the fold so to avoid this from happening a) place the fold on the Inside of the greenhouse - OR - b) add clear tape along the fold.

Mini greenhouses for raised beds with hinged top

Set the greenhouse on top of the raised bed and secure it on the back with two hinges. We placed our hinges 1' towards the center on each side. To keep the greenhouse from flying backwards when you open it or from a strong wind catching it, attach some light chain on each side. This works like a charm!

Mini greenhouses for raised beds with handle and hinges

Attach a handle in the center for easy lifting.

Mini greenhouses with raised beds tilted tops for ventilation

And there you have it! I temporarily stuck some 2 x 2's into the soil and have them resting on the frames for ventilation on hot days. I plan on coming up with a better system when time permits. I'm toying around with the idea of mounting them onto the front of the raised beds with washers so they swing up when you need them or down when you don't. The top of the 2 x 2' would be cut in an L so the frame is held firmly in place. That's all I've come up with so far but I'm open to suggestions and would love to get your feedback!

Mini greenhouses for raised beds

You can see the nurses fold better in the photo above.  The frames probably won't withstand the weight of snow during the winter so we'll have to come up with a plan for storing them. But if they yield a good veggie crop then that's an inconvenience I'm willing to make!

Mini greenhouses for raised beds

The frame laying on the grass in the forefront was removed from our deck (another project in the works this summer) but more about that another time.

Now the fun part...visiting my local garden center and getting my hands dirty!

UPDATE June 12th:  In the few short weeks we've had these greenhouses our tomato plants have grown substantially and have numerous flowers on them and that's without the use of fertilizer.


UPDATE:  June 22nd:  
I have to say so far these have been a hit!  I planted these tomatoes the first week of June (three weeks ago) from 4" pots and already the plants have almost doubled in size and there are loads of flowers and tomatoes. I fertilized them for the first time a few days go so all this growth is without fertilizer!

I THANK THE FOLLOWING BLOGS FOR FEATURING THIS PROJECT:
                 

The Homestead Survival


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