Re: greenhouse framing
Nan Sterman wrote:
>
> >I have forgotten exactly where I read the suggestion that a cheap
> >greenhouse could be erected from a car canopy.
> >If this was the list where that was suggested, could the person who wrote
> >about it please write me privately?
> >I'm interested in exactly how they were suggesting it be done.
Well, I don't know if I did it right or not but I built a greenhouse
from a canopy this last fall. It is a 10x20', 8' tall aluminum frame
that came with a thick white plastic roof and I already had it on hand.
I'll tell you what I did and what I would do if I could start over.
I set the frame and cover up with the short sides to the east and west
so I would have a long side to the sun and a long side in the shade. To
anchor it down I put landscape timbers in the ground as fence posts and
tied the legs to the timbers. I then put cattle panel around the entire
perimeter on the inside to keep the plastic from billowing inward and
knocking plants off the tables.
I then covered the whole thing with 20x100' sheet of 6 mil plastic
sheeting. I attached one end of the plastic to the south side
horizontal bars using large plastic clips purchased at a hardware store
to hold the plastic onto the metal poles. The fun part was getting the
rest of the plastic over the top of the frame. I clipped ropes to the
end and toss them over then pulled the plastic up and over the roof.
After leaving enough room to weight down the bottom, I cut the plastic
with scissors.
I then started on the NW corner and wrapped the plastic across the back,
stopping at the SW corner and cutting it, then starting again at the SW
corner down and around to the east side. I cut the plastic and
overlapped the SW corner so I could easily open it up for ventilation
later which proved to be a wise thing. My doorway was on the east end
and consisted of overlapped plastic held together with those clips.
I realized that the clips would eventually tear the plastic so I bought
pipe insulation and put it over the plastic all around the frame and
down the legs then put the clips over that. That worked very well since
the pipe insulation also held down the plastic for the entire length.
This worked well for about one night. <G> It wasn't warm enough even
with two heaters going full blast. The day before a severe ice storm I
put another 6 mil covering of plastic giving it a double coat. This
proved to be the best thing I could have done because that very night
out power went out at 9 pm and was out for 20 hours with 3" of ice
covering everything here, temps in the low 20's. My greenhouse never
got below 40*F!!!!
In fact, it was raining in there, not good. Now I had a condensation
problem which I solved by pinning full size sheet from the side rail to
the roof peak. It looks like a band of gypsy's moved in there but it
stopped the rain from sprinkling the plants and keeping the humidity to
high. The sheets evaporate the water and any excess went down the side
walls and not on the plants.
When it got to hot inside I added sheets to the whole south wall on the
outside, slipped them under the clips. I could roll them up easily on
cloudy days or leave down at night for extra insulation if needed. On
really bad nights I put blankets along the north wall and they made a
big difference. Next year I'll get some real shade cloth but the sheets
were colorful. <G>
Inside I put 8 foot folding tables covered with table cloths to hold the
plants and had plants underneath. Dormant pots went under the north
side tables, sun lovers on the south. I eventually ended up with so
many plants from cuttings that rooted and sprouting seeds that I quickly
ran out of room. I added two large metal shelving units on the north
end and plastic units went down the middle and up on the tables. A
heavy chain was strung from the roof peak across the entire length and
held all the hanging baskets.
I also have a box fan inside to circulate air and help cool it on warm
days. Now the entire south and east and half the west sides are rolled
up to keep it cool and I can still let down the sheets if necessary.
Most of the plants have been moved out to harden off under trees but
there is still a bunch of plants in there. I also have the triangle's
under the east and west ends opened as a vent.
Next year I will move the greenhouse to sit on a north/south
configuration putting the short side to the north and the door to the
south. The reason being is I could have used the late afternoon sun to
warm the greenhouse as much as possible before nightfall to hold in the
heat. As it was I had to normally leave it open until late afternoon or
it would overheat, then didn't have much time to get it all warmed up
before dark.
The long sides to the east and west will also give me more light for
more plants. Serious shade lovers like ferns can go in the center or I
can add a sheet to part of a section just for them.
I spent a total of two days building this thing, half of that was
running to the hardware store for plastic, clips, and pipe insulation.
I also built it all by myself which was accomplished with shere will
power and adrenalin. It would be much easier with two people,
especially putting on the plastic. I also recommend having more than
one ladder so you don't have to keep moving it a hundred times while
straightening up the tall sides.
Sorry this is so long winded. I can send photo's of my concoction
privately if you want. :-)
Hope this helps,
Linda (who will now be covering it with shade cloth and using it as a
shade house for the summer.)
San Antonio, TX
zone 8b
heat zone 10
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