This is an easy upcycling project that will increase your growing time and add a cute focal point to your garden area! All you need is old windows (these are all over the place! just ask around or search garage sales and/or FB marketplace), some scrap pieces of wood (optional), and screws. That's it! I did put the mat down in case the ground was warm and to protect the seedlings a little more, but this isn't necesary. My husband and I don't yet have a huge collection of supplies laying around in our garage, but I still didn't have to go to the store to complete this project. I count that as a success!
The 5th window will simply lay on top (though you are welcome to get fancy and add a hinge!).
If possible, a second set of hands comes in handy here, at least to get it started. This is where I used scrap wood. I fit the windows so that two were on the outside and two were on the inside. Then I used a scrap piece of wood to attach the two windows on the outside. See the third photo below for a visual.
Do this on all the sides on both the top and the bottom (if you feel it's needed, like I did). Make sure to position the screws so that the box will not shift when it is moved. I did three screws on each.
Ideally, I'd recommend getting a thermometer that you can leave out there and keep an eye on the temperature from inside. But all I had on hand was a little humidity thermometer, so use what you have! It was in the mid 50's outside, and the greenhouse read high 70's with the lid off and high 80's with the lid on! This was on a sunny day, so I'd imagine a cloudy day wouldn't be quite so extreme. I'll try to post an update when I can test it out!
The beauty of leaving the lid unattached is that you can adjust it depending on the weather. On this warmer, sunny day, I decided to turn it so it didn't get too hot, but was still protected. You could even take it off completely and the seedlings would still be mostly protected from any cool breeze.
I do want to make a quick clarification. You may have heard both of these terms. In general, I think of a greenhouse as a structure that has a more controlled climate with things such as heaters and fans. A cold frame, on the other hand, is simply a structure to protect from the elements so you can keep plants into the winter. But a greenhouse is technically a structure that protects plants from the elements, and I'd say this qualifies!
There you have it! Easy, right? If I can do it, anyone can, believe me (just ask my husband). One of the biggest benefits to this little greenhouse is being able to move my seedlings outside. In a small apartment with windows only on one side, I've been limited over the years with the seeds I decide to start. They usually end up getting leggy trying to reach for the light. This is a great solution for small apartment living! Be sure to let me know if you try this out! And add any tips that you find while making yours to the comments so we can all learn together.