Build a greenhouse in zone 4?

DH and I are trying to figure this out, and neither one of us knows anything about greenhouses, much less in this zone. We are going to build, (hopefully if we can get this figured out), a 12 x 16 frame from 2x4's leftover from when we built the house. We were looking at some greenhouse plastic glasslike material at Menards last year for the rest, but I can't remember what it was called. We need to get back there. It was not glass, but a plastic material that was close to glass.

Our problems/points of disagreement come from the heating, lighting and ventilation aspects of this project.

DH agrees that it does need to be heated a couple months a year, and I think we'll go with propane. Our house is electric heat, and we don't want to heat it that way. Too expensive. Does anyone else heat with propane, and if you do, what kind of setup do you have?

Lights....I want lights so I can work out there a bit longer in the evening than he would like me to. I don't see a problem with stringing an extention cord and using a shop light. Plus, wouldn't that light provide a bit more heat when needed? Or, should we get our electrician up here to hardwire the electricity in, since there will be water involved in growing the plants?

Ventilation....neither of us have any idea how to go about this, and what we actually need to do to provide it. Any ideas/info would be much appreciated.

Plus, we don't have a lot of shade, so we are worried about plants cooking while we are at work during the day. We will put it on the north side of the house, but still not much shade. Do they have to be shaded? If we could figure out the ventilation problem, would that also solve this problem? We are away from home from 8 AM to 6 PM weekdays, and not within a distance to run home and shade it if it gets real hot out.

Oh, the foundation. Do we just put it on the ground, or would it be better to put it on a platform, built much like a pallet, with slats for drainage and such?

Any help or info would be much appreciated and printed out. We aren't going to get this going this spring, but maybe have plans in place to get it started this fall, so it's ready for next spring.

Joan, if you are going to heat it in the winter be prepared for some hefty propane bills. We have a 30 X 48 in zone 5a and it cost about $600 for ten weeks from March until May (we also use a double barrel wood stove).

There are a lot of good supply houses for plastic - check FarmTek online
http://www.farmtekcatalog.com/search.asp?SearchItem=greenhouse+plastic

We bought the one with roll up sides and love it.

Yikes! I don't know if I want to tell DH that or not. I didn't realize it would take that much propane. Hmmm...maybe I do need to think of a different way to heat it.

I'll check out FarmTek, thanks!

Not sure what panels you saw, but 8mm 3 wall polycarbonate panels
will cost you about 1600 just for the panels and 2500 - 3500 for 16mm and 25mm
panels, these would give you a high insulation factor.

there is also the single wavy corrugated type that are cheeper , 10 to 30 bucks a panel
and they are 26" x 12 feet long.

then were down to just using poly film 6mm.

up north i wouldnt do a GH with just a single layer , i would double it so you would
have the outer layer and then a layer on the inside with a blower inflating the gap
between them.

once you get your covering figured out with how much you want to spend then
you can do some things on the inside for free heat ..

Black 30 to 50 gallon drums filled with water along the north wall i think it is.
these will heat up durning the sunny days and release the heat at night.
Take note .. SUNNY DAYS ... here where i am we had 2 months with overcast
days and that dont help much.

you could heat with a waste oil burner ( used motor oil or veggie oil from deep fryers ) prolly can get that from the local car/truck oil change place for free or resturants.
you want to keep the waste oil as pure as you can, no gas , antifreez mixed in with
it. ( it wont burn clean, get alot of ash build up).

you could run hot water base boards under your benches where the heat would
move up inbetween your plants.

And/Or run pipes under the flooring. sand .. water lines ,, sand , pavers/crushed stones

Wood stove was also mentioned above which you could use to heat water.
make a boiler attacment for it.

you wont get that much heat from your lights, best to just leave them out of the
heating figures.

if you have a big compost pile, will generate some heat as well.
the insides of a big wood chip pile can get up to 160F, another
source for some buired water lines for hot water.

thats all i can think of off hand now ..

but build that GH, you will have fun in it.
and once you get it up, then you can see how it does in the cooler
months and go from there. keep records of how cold it get and when.

Great info, thanks! I'm going to do some research on all of them so I have all the facts and figures before I give them to DH to ponder.

I really like the idea of double walls with a gap inbetween.

We figured it was going to cost us around $2000, but now it looks like it may be a bit more.

Great info, Sparky. Eventually DH is going to be building me a greenhouse in a couple of years and he was thinking of using a wood boiler. I've heard of using the black drums to so that might be another help.
Thanks!
:) Donna

Hi Joan

Was reading about your wanting information on building a greenhouse and then heating it. My son in law built my greenhouse which is all redwood and all double polycarbonate for the panels. It is 12 x 12 with peak roof since we live in Northern Michigan and have lots of snow. That in itself, materials alone for just the greenhouse and that included the stain as well was $3000.00.

MY DH installed a propane wall heater which I turned on in March the first year I had it, and ran it till the end of April. The cost of heating was over $300.00. And I kept it on pilot only. I pretty much figured out that was the the last time I would do that as I could buy alot of plants for $300.00 as opposed to seeds.

I have an exhaust fan in mine and I keep the thermo at 75 degrees which keeps the Greenhouse from over heating. It does get hot in there if you don't have an exhaust fan with a thermostat. I suggest you put that in.

I now do not start my seedlings till the middle of April and at night time I cover them up with plastic so they don't get chilled or frosted. This method works for me.

I do have water in my greenhouse and the hose was run underground, the same for the electric. We ran cable underground.

12 x 16 is a pretty big greenhouse....you may want to consider something a tad smaller.....I have enclosed a picture of mine.

Good Luck!

Deann

Thanks Deann! What do you heat your greenhouse with now?

I start my seeds under lights in the basement, so I would only need a heat source from May 1 to June 1, and then probably only when we get an unexpected cold snap.

I want to build it big enough from the start, so I don't regret it later. I want it 12 foot wide so I can put my potted brugs and other plants in there, on the floor, in the summer when storms threaten. Then I want 3 foot wide shelves on each side, so that leaves 6 foot in the middle for the potted plants to sit, and me to walk.

Joan.....Actually by the time May 1st arrives, the Greenhouse stays warm enough so the plants do not suffer. As I said....I cover my seedlings at night with plastic if I know the temps are going to be below freezing. However, I do not have Brugs so that is a whole other situation. Most of my seedlings have dome covers which protect them at night should it get real cold....but for the most part covering with the plastic has worked for me.

Good Luck

Deann

Great, thanks Deann!

Joan, I did a little resreach. Go to www.poly-tex.com
Click on Kool House under commerical growing.
These are sold with single plastic, but you can add a second layer.
Go to Farm Tek, they have fans & intake shutters. There is a chart there to figure how much fan you need for the size of your house. Put in some kind of heat source, these southern zone,(anything over 4), don't realize it can freeze any day of the year! Put fans & heat on theromstates. Sleep & work in piece, as things will take care of themselves.
I got to ramblin! LOL!
Prices at Poly-Tex are very good. Also a house like this will last many years. The left over lumber will not like all the moisture.
Good luck with your new venture!
Bernie

This message was edited May 11, 2005 7:51 PM

Thanks Bernie!

I got a Farm Tek calalog and we've been looking it over. It's hard to figure all this out. All the help and suggestions really help a lot. For us, this is going to be a big investment, so we want to do it right, or as close to right as we can.

I'll go check out that Kool House and print some information for DH to look over tonight too.

I hadn't thought about the wood not liking the moisture in the greenhouse. It seems like lots of greenhouses have a wood frame though.

I also hadn't thought about putting the heat and fans on thermostats. I've been worrying about how to make sure the plants don't cook if it gets hot out and we are at work. I love that idea and will be one that I push for. Thanks!!

Bernie, the link above doesn't work, but this one does. www.poly-tex.com

Joan.. Some places have automatic openers for your upper greenhouse windows that are heat controlled. Non-electric. Pretty neat I think

Oh, sure, I spelled it wrong. Sorry. I usually test the link, but I was in a hurry this morning.
Bernie

No problem Bernie, I found it okay. I've printed a bunch of stuff out for DH to look at. I'm getting excited about this!

Jazz, that's a good idea too. I'll research that a bit. Thanks!

Joan......I have a vent at the top that operates on solar power, and opens with the sun and with the exhaust fan going with a thermostat, it keeps the temps in my greenhouse where I want them...

Deann

What if it's sunny and cold? Does it still open?

Our fans will run on temp inside. One day it was still in the twenties outside, but the sun warmed the inside to the 80's, so fans start running.
Bernie

That makes sense, thanks. The fans stop again when it cools down I'm assuming. What temperature do you have it set at?

We try to not let it get over 80º. Setting depends if the sun hits the themostat or whatever. Just keep changing it until you get what you want. We run between 55 & 60 at night. Plants do real good at that temp.
Bernie

Great. Thanks Bernie