DIY Mini Window Greenhouse

DIY Mini Window Greenhouse

Recently, I took a tour of our new side yard garden update where I transformed it from 4 rectangular shaped garden beds into a keyhole garden ready for all the fruits that I can think of! While showing my tour via IG stories, I also shared my completed greenhouse, which I had created from upcycled glass windows. And everyone seemed to love that part the most! 

So, I thought that with such strong interest in my mini-greenhouse, a quick blog post on how I created it might be useful. Even though this particular project was years in the making, the entire greenhouse could have likely been completed in one fully dedicated afternoon. 


Below are a list of materials I wound up using to complete this project:

  • Six thrifted glass windows: 4 larger windows and 2 smaller ones
  • Eight L-Brackets - 6 small and 2 medium sized
  • Six hinges - 2 for the door and 4 for the roof
  • Scrap Plywood
  • Small Screws (Less than 2" [5 cm] long])
  • Vinyl "Fabric" 
  • Flat Bricks (optional)

It's really important that when building your own greenhouse that you find windows that are all relatively close in size for the 3 walls + door side as well as for the roof. The walls don't have to be the same size as the roof windows, but the roof windows should be the same size as each other if that makes sense?

For my greenhouse, my window measurements are as follows:

  • Door - 31" W x 36" H (78,7 cm W x 91,4 cm H)
  • Three Walls - 28" W x 37" H (71,1 cm W x 94 cm H)
  • Two Roof Panels - 24" W x 19" H (61 cm W x 48,3 cm H)

As you can see, my door was slightly wider and shorter than my three walls, but not by much. I was able to give the illusion that all four windows were the same. I did this mainly because I had picked up my thrifted windows at different times and from different places without any thought as to how this project would eventually come together. I got very lucky that all of my windows were around the same size!


The Process

To put the base of the greenhouse together, I simply lined up two of the longer sides of the windows together at a right angle and attached three metal L-Brackets I happened to have on hand. They were really tiny, so I opted for using three per corner to give extra stability to each wall! 

Close up of a black mini-l bracket holding together two sides of the greenhouse walls

When attaching my greenhouse windows to one another, I tried to make sure that all of the solid edges were facing one way and all of the hollow edges were facing another. 

A close up image of the groove on the top portion of the door to the greenhouse

This is what the hollow edge of the windows looked like - Just a groove carved out of a non-glass bearing edge. 

With three of the windows attached together, I went ahead and cut some scrap plywood so that it measured around 28" (71,1 cm) wide, which was the width of the back window. I attached my two scrap pieces to the "bottom" of the greenhouse. 

An above head shot of a few plants inside the greenhouse sitting on top of a brick base and two white bits of scrap plywood

Two things: I only used two scrap pieces of plywood because honestly... that is all I had! If I had had a larger piece of plywood, I would have opted for attaching a solid piece to the entire bottom edge of the greenhouse. Speaking of the "bottom" of the greenhouse, I used the side of the greenhouse that had three solid edges to firmly secure my scrap wood into each window, reserving the hollow edge for the roof.

With the base attached, the entire greenhouse was beginning to feel a lot more sturdy! At this point, if you are able to, I would suggest moving your greenhouse into its final location while it is still easy enough to move. Once the roof and door go on, it get's a bit heavy / difficult to maneuver. 

For my greenhouse, since it didn't have a full base, I decided to lay out a thin brick base where I wanted it to reside. This helped to not only provide more stability for the greenhouse, but it also will keep the bottom edge from being in direct contact with damp earth. This should extend the life of both the plywood base and the wooden windows themselves, hopefully preventing them from rotting too soon. 

Greenhouse with its door open, revealing the plants that will be vacationing inside over the winter.

Can you make out the thin layer of bricks sitting underneath the greenhouse? This is helping to maintain a sturdy and level base as well as keeping the bottom of the greenhouse from sitting in wet mulch. 

Once my greenhouse was in place, I added my door. To do this, I simply attached two hinges to the window on the left side of my greenhouse and then attached them to the door window. I made sure that the door could easily open and close and then gave myself a high five!

Close up of a silver hinge attached to the outer door of the greenhouse

Next, I attached the to roof windows together with my remaining L-Brackets along the longer edge. Done and done!

The roof took me a bit of thinking time to figure out just how I could attach it. An L-Bracket wouldn't work because a roof generally doesn't attach at a right angle. I also didn't think I could screw directly through the roof into two side walls without potentially breaking something. In the end, I decided to use hinges to attach the roof to the walls.

Close up of gold hinges on the inside of the greenhouse attaching the roof to the walls a an obtuse angle.

The hinges worked out brilliantly! Because they are hinges, they were able to be attached at the perfect angle, securing the roof to the outer walls with minimal effort. And the hollow edges of the windows added additional support to the roof. I will note that I did have to slightly bend the L-Brackets along the center edge of the roof a bit in order to get the entire roof to be wide enough to fit the width of the greenhouse. Again, I got super lucky in that all my windows sort of fit into one another perfectly without much hassle. 

Because my roof pieces were much smaller than my greenhouse (along the width of the walls), I had to decided where it would sit on the actual walls. Would I set it towards the back? Or the front? Or the middle? After playing around with placement, I landed on setting the roof towards the back of the greenhouse. I figured I could close up the front portion with leftover vinyl fabric we had purchased for a failed project. 

The full greenhouse viewed from the side. A willow diamond shaped fence is seen in the background and a small, tilted pot of plants in the foreground

Finally, my greenhouse was looking like a real greenhouse! All that was missing were the finishing touches. For me, that not only included sealing up the the triangular opening created by the roof but also sealing up my three window walls as all three had lost their glass at this point. It had simply fallen out - whoops!

To seal everything up, I took my heavy duty stapler and my vinyl fabric scraps and began stapling it to the inner walls of the greenhouse. I chose a really cold day to work on this and as I started getting more of the vinyl walls into place, I immediately felt a temperature shift inside the greenhouse where I had been sitting. It got cozier, which made me hopeful for my future plants! 

The inside of the greenhouse filled with plants and the walls lined with vinyl sheetingThe inside of the greenhouse filled with plants and the walls lined with vinyl sheeting

I literally finished my greenhouse right as the weather was starting to shift. It is still currently Fall in Georgia, but soon it will be Winter and a few of the less hardy plants I have will begin making their way into my house as well as this new greenhouse which is so exciting! I hope that they enjoy their Winter vacation, safely tucked away in the side yard garden!

A close up view of the inside of the greenhouse filled with plants and the walls lined with vinyl sheeting taken from outside the greenhouseA close up view of the inside of the greenhouse filled with plants and the walls lined with vinyl sheeting taken from outside the greenhouse

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