For my DIY greenhouse #2, I started from scratch. It's a raised bed design that was built on a vacant piece of ground that was home to more weeds than you can imagine. The idea was to build a greenhouse with a raised bed that was conducive to harvesting while in a standing position. The design also made use of a perfectly clear southern exposure and an area that was protected from harsh northwest winds.
This homemade greenhouse features power poles as the foundation for the building and the sides of the raised beds. Chain link fencing top rail is used as the main structural material above ground. The ends are made from 2 by 4 lumber, painted white to reflect light.
There are two raised beds inside, each roughly 3 feet wide by 36 feet long. The sunken walkway between the beds is roughly 3 feet wide and nearly three feet deep, so harvesting vegetables is as simple as reaching out to get them...there is no bending over.
If your DIY greenhouse is away from the home like this one, you'll have to run water and electric lines. Since I knew I was building a third greenhouse nearby, I sized the electric lines to serve both structures, and installed an outdoor panel with a breaker assigned to each greenhouse.
Here is a picture of the finished building inside, just after the squash seedlings were planted. The summer squash are on the right and the winter squash are on the left.
There are still minor finishing touches to add, but it's a fully functional greenhouse. In addition to squash, it's home to a wide variety of cucumbers.
The photo above shows cross bracing on the walls and angle bracing running from the roof to the sole plate. This structure is very strong and capable of withstanding 100 mph winds.
Shown below are two pictures of the interior of the greenhouse, facing the same direction as the photo above. The picture immediately below is of the winter squash bed. It is completely overrun with bushes and vines of six varieties of winter squash.
The photo shown below is that of our summer squash plants. There are six varieties of squash, some zucchini types, and others are patty pan types. All are wonderful, and you can see that they too are performing very well in the protected environment of the greenhouse.
In case you weren't aware, squash like it hot, and my DIY greenhouse accommodates their interest in heat quite well.
Below is a picture of just one day's worth of harvest from this DIY greenhouse. I harvest about this much every few days. If you build your own greenhouse, you'll harvest a lot more squash than you will if you leave them exposed to the elements outdoors. We estimate that our yields are doubled when plants are grown inside of a greenhouse. Our squash varieties include Butterstick, Starship, Sunburst, Woods Prolific and Magda.
My sweetheart Ellen is making squash casseroles every few days to place in the freezer. We'll be enjoying the wonderful taste of squash throughout the winter, while we harvest other winter crops from this greenhouse.
If you are going to tackle a DIY greenhouse project in an area with heavy wet snows, this is the design I would recommend. It has a steep roof that sheds snow well, and the basic design can be built on power poles or attached to the ground using higher walls.
One last note, having a sunken walkway was an easy way for me to make raised beds and still keep the beds at and below grade level where they would naturally retain energy from the earth. So, instead of moving dirt up and into a couple of huge raised beds, I simply dug the soil out from between the two beds. That reduced the soil movement effort by two-thirds, and that saved a lot of work.
Here are details about my DIY greenhouse #2 that will be helpful if you decide to start from scratch and use metal tubing to build one yourself.