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I can’t believe I haven’t written about our greenhouse. We’ve been using
it for at least a year and a half now, and I’ve been oddly silent about
it. I guess it’s probably because it’s not 100 percent complete. We
have one small area that still needs a permanent covering, the windows
need new glazing, and it is in desperate need of new paint. But it’s
still functional and gets a lot of use. And it only cost us about $300.
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That might sound like a lot of money until you consider that this
greenhouse is 8 by 12 feet and uses glass glazing. Buying a glass
greenhouse that size will generally run you around $5,000.
Why Choose a Glass Greenhouse?
Why a glass greenhouse? Why not just make a hoop house to save money?
Hoop houses are great, don’t get me wrong, but they just don’t stand
the test of time. While they are cheaper to make upfront, there are some
concerns you have to take into consideration. The material usually used
for hoop houses is plastic sheeting, which doesn’t last more than a few
years, even if it is UV-resistant greenhouse plastic film. I’d prefer
not to have to add more plastic to the landfill or spend the money
replacing it. Also, you have to give special consideration to the hoop
structure. PVC pipe will degrade the plastic through chemical reaction
faster than it normally would degrade (and most isn’t UV resistant), so
you either have to wrap the pipe or use another material, like
galvanized pipe, which increases the cost. Plus, we have a very windy
site for most of the year, and plastic sheeting just wouldn’t hold up.
Polycarbonate greenhouses also degrade from UV but last substantially
longer than poly film. Polycarbonate is a plastic, and even though it
may hold up for 10 to 20 years when properly treated with UV
stabilizers, it will discolor and become more opaque after time. It also
becomes brittle. Double-walled polycarbonate adds the benefit of being
more insulating than both glass and film. It can be quite pricey,
though. Not as expensive as buying glass specifically for a greenhouse,
but if you can do glass, which is superior to both film and
polycarbonate, for less than either, why wouldn’t you?
Sourcing Free Windows and Materials
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It’s all about the windows. It is amazing how many people are trying
to offload free windows. Craigslist is where we scored the majority of
ours. We also scored a free door, which was half-window, from my best
friend, who had just bought a house and wanted to replace her front
door. We stockpiled old windows until we had what we felt was enough to
begin building. Before starting, we laid out the panes on the ground so
we could get the right configuration to fit the walls of the greenhouse.
Do this carefully. We had a few casualties but fortunately had enough
windows to make up the difference. We also made sure that we had some
windows with frames so we could open them as needed when it got hot in
the summer.
Next, we had to figure out where to site the greenhouse. We had a
space on the north edge of our property that wasn’t shaded, and it
wouldn’t shade out anything. We made the long 12-foot wall south facing
to maximize sun exposure. We also decided that, since the north wall is
facing a fence, we could just use plywood for it. We framed up the
structure with new lumber, which is where a good portion of the money we
spent went. The most costly part of this job, however, was the roofing
material. We used some of the extra pavers we had on hand to level the
structure, since our ground slopes. It was also imperative that we add
extra bracing, as the weight of the windows can be quite substantial.
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The biggest score from our window search were these two 6-foot-long
windows that someone had purchased and never bothered using. They easily
spanned the whole lower half of our south-facing wall. It was a tight
fit, but we got them in. From our next-door neighbor, we also got
narrower windows that flank the door (seen in the first photo).
Once we got most of the windows in on the south-facing wall, we
started framing the door and getting the roof joists up. Sexy, ain’t it?
We decided to do a simple sloped roof rather than a gable so that the
south side would get even more sun exposure, especially in the winter,
when the sun angle is lower and when we need the greenhouse the most.
One note: A door that comes with a jamb will make framing much easier.
Once the door was in, we were able to finish up adding windows and
roofing. For that, we used clear corrugated plastic sheeting. It’s not a
particularly pretty greenhouse and it does need a coat of paint, but
it’s definitely functional.
Greenhouse Interiors and Greenhouse Floors
Of course, you also have to think about the interior. Where are you
going to put plants? And what about the floor? We scored some pea gravel
off of Freecycle, enough to put down a nice 3-inch layer. We put down
weed cloth first, though, so we won’t be fighting the never-ending
onslaught of bindweed and Bermuda grass inside. Tom build a fantastic
8-foot-long potting bench out of scrap wood, and we bought some heavy
duty utility baker’s racks for the plants. We’ll probably switch the
locations of these, putting the potting bench on the east-facing wall
and the racks on the south-facing wall, so we can add another rack.
We’re also using an old compost bin (our chickens do all of our
composting now) as soil storage.
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Have you built your own cheap greenhouse out of scavenged materials? Do you have photos or tips to share? Post them below!
This post originally appeared on HOMEGROWN.org.
Rachel’s friends in college used to
call her a Renaissance woman. She was always doing something crafty,
creative, or utilitarian. She still is. Instead of arts and crafts, her
focus these days has been farming as much of her urban quarter-acre as
humanly possible. Along with her husband, she runs Dog Island Farm,
in the San Francisco Bay Area. They raise chickens, goats, rabbits,
dogs, cats, and a kid. They’re always keeping busy. If Rachel isn’t out
in the yard, she’s in the kitchen making something from scratch.
Homemade always tastes better!
