chaz wrote:
I am considering making a small greenhouse, before I actually make the
plunge into something legit. I can buy a greenhouse locally for about
1100.00 which would be an 8x10 portable unit. Its like a storage building,
but with translucent fiberglass panels, no floor, and windows for
ventalation.
I am looking at making a 10'x10' x 3' tall stucture from PVC and clear
plastic. I know its not a greenhouse, maybe a souped up cold frame, but it
would be cheap. I thought I could string up some lights (4?) to keep the
temps out of the freezing range? I have some lemon trees I want to grow over
the winter and there are too many to bring in doors.

I would love you guys to shoot holes in this idea. I have ZERO
experience with a greenhouse.

chaz






Things to consider:

The clear plastic you buy in the hardware store is not generally UV
resistant, and will start cracking in one to two months of exposure.
Make sure you buy the UV stabilized stuff. 6 mil is common. Look for it
in greenhouse supply houses.

The PVC frame has to be strong enough to withstand wind and snow(?)
loads when the plastic is on it. You don't want a flat roof. You need
enough slope so rain will not form puddles in the plastic. Rain is
really heavy when it collects in a dip in the plastic, and can rip through.

3' high is rather cramped when you're trying to work inside (maintaining
your lemon trees as necessary, or just planting them). Making it 5' high
wouldn't take significantly more framing or plastic.

Ventilation is NECESSARY. Preferably automatic. On a sunny day, the
temperature can get over 130F, even with 30F outside. You want it
automatic so you can go to work and not have to worry about the sun
coming out in the afternoon. There are automated cold frame devices that
would probably work.

If you want to keep it from freezing, a lot of water containers will
help (assuming you're in a temperate region where lemon trees grow).
Water will release heat as it freezes, keeping the temperature at 32F
until it's all frozen. If the temperature gets below freezing for
several days at a time, this won't work well. I find a cheap space
heater (set on concrete blocks) will keep a fairly large space above
freezing in New England in the spring (not the winter). Lights running
all night might be an annoyance to your neighbors. The space heater is
not quite so visible.