Garden & Greenhouse


DIY Greenhouse – Converting a Wood Shed into a Greenhouse

Posted June 30th, 2017 by Clair Schwan in ,

My small greenhouse had humble beginnings. It’s an old shed just the way it was when I bought my home. It had a sagging roof, rotting foundation, dirt floor and only one window; it wasn’t a nice place to spend time, but it became my first homemade greenhouse.

I used the outbuilding as a chicken house for several years, and also stored yard equipment there after I built a separate place for my fowl out behind the barn. At best, it was a cobbled together shop constructed of recycled wood and used for various purposes including raising rabbits. It was a well-used, dimly lit space about the size of a single car garage.

Before converting it into a greenhouse, I considered making it a shop, but it was just too small, and it was too nice to waste on chickens. I thought about razing it and starting from scratch, but decided the framework could be converted into a small greenhouse. So, I salvaged what I could and made a nice DIY greenhouse out of it.

The key to making the decision was its orientation. The length of the building faced south, so it would suck in all of the low southern sun during the winter, and that’s just what I wanted…a place to keep cold hardy vegetables during the winter months.

It turned out to be just the right size and location for a “kitchen greenhouse” where fresh thyme, tomatoes, onions and greens are close at hand. This small greenhouse is also where our eggplant, pole beans, snap peas, snow peas, Swiss chard, spinach, lettuce, cucumbers and a full assortment of herbs reside.

It has become well-functioning, small and most importantly inexpensive greenhouse. It measures roughly 15 feet by 30 feet and has a 10 foot high roof peak. Our small greenhouse is 450 square feet, and we wouldn’t want it any smaller than that. When many people think of a small greenhouse, most often they’re thinking about something like a hobby greenhouse, perhaps the size of a bathroom or a full-size van. That’s too small for vegetables because by the time you let your plants get to their full size, the space you have left over for walking, relaxing, harvesting and simply enjoying your greenhouse is quite limited.

Even if you’re thinking about just a modest size greenhouse, let me suggest that you decide how large you want your growing area, then double that square footage. That’s probably a good way to determine a comfortable size for your greenhouse. It might not seem like a small greenhouse to you, but if you don’t allow a generous amount of space for you, your tools, your supplies and some swingin’ room to get things done, you’ll soon find that the greenhouse you built is just too small indeed.

This greenhouse provides sufficient protection to allow our snap peas to reach 4 feet high and tomato that are about 8 feet tall. It’s amazing how much better plants grow when they are protected by a greenhouse. If you have an unused shed, you might consider building your own small greenhouse.

A smaller structure would lead to feeling boxed in. A good rule is if you don’t have room to be comfortable, you’ll likely spend less time tending your garden, and that tends to defeat the purpose of having a greenhouse in the first place. Build your greenhouse larger than you think you’ll need, and you’ll never regret having the extra room. Besides, larger structures cost less per square foot of space.

If you build your own greenhouse out of wood, be aware that you need to sand and paint the wood, and this can be an expense and quite a job. Also, wood can rot in a damp environment, so be aware before you build.

The north wall and a small strip of the north roof have sheathing left in place, but the remainder of the building is covered by woven ripstop poly that does a nice job of letting in light and resisting the harsh weather we have out here on the prairie. If you decide to build a small greenhouse like this, it would be ideal if you had one like this, where there is electricity and water already installed.

To determine the right size for even a small growing space, rope off an area on your driveway or in your backyard and pretend to use the space. Get two people in there using the space and simulate beds and tools and a place to sit, and don’t forget a table or bench or sink. Then, after working for a while in the simulated work environment, you’ll likely have a much better idea as to what size your greenhouse should be.

Clair Schwan is an avid vegetable gardener who considers his gardens to be important assets. To him, vegetables in the garden are a bit like money in the bank. It’s all part of his self-reliant lifestyle. See his adventures in gardening and more at

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