And Then There Were Two (Greenhouses)

By Cam Mather

Part of my goal in running a CSA that will supply a dozen families with produce over the summer is to extend my growing season. In terms of extending the season at the beginning I got off to a slow start, because I didn’t get my greenhouse built in time. But I plan on coming on strong this fall after I got my first (glass patio door) greenhouse built.

Then I started thinking about the raised beds in the barn foundation. They have always been a great place for heat loving vegetables (peppers, eggplants and tomatoes). In the past I’ve had two problems with these gardens.

My first problem was moisture. Since they are raised beds, sitting on the concrete floor of the old barn, they tended to dry out fairly quickly Also, the soil always ended up with a hill in the middle and water tended to run to the sides whenever I watered.

The second problem was our pesky early frosts here. We’ll often get a frost in September that will kill a lot of stuff. Then we may go another month before our next frost hits. This drives me nuts. I just knew that if I could protect the plants from the first frost, they’d keep producing for the rest of the frost-free month, but I had no convenient way to protect them.

So last fall when I borrowed Heidi and Gary’s backhoe, I started moving soil from outside of the barn foundation into the raised bed area. As always it was a crap load of work, because the bucket wouldn’t fit through the door. So I had to shovel it by hand into the area between the two raised beds. I decided if I was going to cover this area I might as well optimize how much garden space I was protecting. This also meant that I’d have more soil in the one garden and a more level surface to allow water to be absorbed and not run off so much.

So after I finished the glass greenhouse (shown here)  I started work on this second “greenhouse.” Really, it’s just a raised bed that I can conveniently cover during cold nights. As always cost is my biggest parameter. I bought some cedar posts locally, which were about $4 each, then some spruce 2x4s for the cross pieces on top. An 8 foot spruce 2×4 is $2.50. How is it possible to cut that tree, strip the branches and bark off, ship it to a mill, cut it down to size, and then ship it to Home Hardware in Napanee, and still be able to sell it for $2.50? The mind boggles.

Then I got really lucky when speaking to my friend Ian Graham who has greenhouses. One of Ian’s greenhouses had been damaged and he ended up with a section of plastic that he offered to me (when I asked, of course). When our friends Ellen and Jerry came for a visit to deliver our new blueberry bushes they were able to bring the plastic too. Thanks Ian! It’s awesome! And thanks Ellen & Jerry too!

So here it is, my second greenhouse. Yes, it’s fairly low, but I did this intentionally. I didn’t want to pay for a commercial steel greenhouse and I didn’t want to engineer one that was tall and have to deal with wind forces. This one is low and surrounded by the barn foundation wall. Yes there will be wind but I think with the low profile and natural wind break of the walls it shouldn’t be too big a problem.

Once the danger of cool nights is past I may take the plastic off for the rest of the summer and potentially some of the 10-foot stringers. I’m not saying that it’s likely I’ll forget they’re there and whack my head, but it is a possibility. And if it was to have happened already, I’m happy to report there was no concussion… that I know of… well at least not that I noticed after I came to.

Filling in the space the between the two separate raised beds was a stroke of genius. I can’t believe how much better this garden is holding moisture. There’s just more soil in it, and with a uniform flat top it’s doing a great job of being one less thing for me to worry about. There were times last year when I’d get over-worked in the main garden and forget to water these beds which would put the plants under real water stress.

Right now I roll the plastic up in the morning and roll it back down after the sun goes down. I love stepping inside under the plastic in the morning before I roll it up. It is noticeably warmer than outside. And the air is really moist. There is a lot of condensation, which drips off the plastic and falls back down on the soil. I’m not sure if I’d be losing that moisture at night if I didn’t have the plastic over it, but regardless, it’s nice to see the water staying where it’s needed.

And yes, I should shut up and spend money and buy a real greenhouse!

I’m getting there. What these two projects are allowing me to do is evaluate just what I can achieve with an unheated greenhouse in our northern climate. If I can increase yields and extend the season enough, then yes, I’ll bite the bullet on the big one.

With projects like this sometimes I like to move slowly and understand exactly what it is I’m trying to achieve. It seems very common to me for people who want to start growing food (and have the money) to just put up a greenhouse. I’m just not sure they take full advantage of it. I’m hoping that once I understand its benefits I’ll be better able to decide how much to invest in a larger greenhouse.

For now I bought some cedar posts, some 2x4s, some screws and got the plastic for free. I’m well under $100 for this greenhouse.

Oh yes, and if I were smart I’d factor in the expense of a proper hard hat that I’d force myself to wear whenever working in the greenhouse as it’s configured now, otherwise I may not have the brain cells left to figure out how to build a greenhouse of standup height!

4 Responses to “And Then There Were Two (Greenhouses)”

  • Cathy:

    FYI:You have real greenhouses, that work. Just because you didn’t waste thousands of dollars on a commercial unit or even a hobbist type, you have real efficient spaces you won’t have to make payment on for 10 years. How ever long they last will be pure profit after collecting your first $100.00 from clients. Quit knocking yourself. You have money in the bank instead of debt.

  • Awesome job! Reminds me of all the work WE put in when building our greenhouse up here in Sudbury (over top of 7 existing raised beds). Paid $35 for a humongous sheet of plastic being discarded by a local commercial greenhouse and used only a portion of it on our, hmm, 20-24 foot? “building.” We used a free portable garage skeleton and a purchased one that wasn’t quite the same size and cobbled them together. So our building has two peaks with a catchment place in the middle that sheds water nicely into a rain barrel. Removing snow is a bear, though. There is a window in each peak, back and front, that we heavily depend on to let hot air out. Without those open, we’ve toasted plants even in April so we’ve learned to watch the thermometer closely–even hourly. The skeleton feet are sunk deep into the ground so the whole building holds up well under the winds we get (don’t know how fast they are) but you can see it tilt ever-so-slightly to the right.

    Hubby wants to build another greenhouse but improve on his methods. For instance, it is oriented in the wrong direction for air flow through it in hot weather. Even with the windows open we need more ventilation–so we’ve cut out 8 doors for the summer (they’ll be put back when it gets cold again) and this year, since we now have cats, hubby put chicken wire “screen doors” in their place. Even with all the doors and windows, last year we hosed down the greenhouse a few times and even put a fan in there. I do everything I can to keep the temperature below 40C and sometimes that’s tough! We’ve already had a couple days like that–and it’s only the beginning of June! Shadecloth is on my agenda for July–haven’t yet found a local source for that…

  • Cam that looks great! I would go to your local library and get books from the 70’s on appropriate low tech if I were you. You really don’t need to spend thousands or even hundreds on a greenhouse, there are plans for them everywhere. My friend who runs a CSA here in N. AZ built theirs out of old windows and metal studs, with shelving for starts and bathtubs for beds. It’s not particularly pretty but it works stunningly well and has held up to our 70+ mph winds for seven years now. We’ve tried to do a plastic greenhouse over our raised beds but they always get ruined by the wind, so I’m looking at acquiring more sliding glass doors and building one like yours and my friend’s. That way I could garden year round.

  • Gerrit Botha:

    Congratulations! Looking forward to hearing how it works out.

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About Cam
Cam Mather and his wife Michelle live independently off the electricity grid using the sun and wind to power their home and their CSA. Cam is working towards the goal of making his home “zero-carbon” and with his extensive garden he aims to grow as much of his own food as possible. He is available to speak at conferences and other events and has motivated many people to integrate renewable energy into their lives, reduce their footprint on the planet and get started on the path to personal food, fuel and financial independence.
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