Ok, I decided to go with a greenhouse this year

I'm gonna give it a try and see how it goes. I only hope we get enough sun. I have an RV cord I can run out there and provide supplemental light for a couple hours a day when needed.
 
The frame is from a canopy tent I got from COSTCO a couple years ago. The sun and wind made quick demolition of the plastic tent material, but the metal poles alone are worth the price of admission. It's 20 feet long, but I only used one section to put the ends together. So it now measures 10'x7'. The center ridge is about 9.5' tall, and about 6.5' at the sides. I still need to square and level it best I can, but I'm pretty beat up today just getting this far. I plan to shop around for a roll of plastic, maybe 4mil or 6mil, whatever I can afford when I find it. Would be nice to find a 10' wide roll just so I won't have to patch it together in pieces. I learned from the COSTCO tent experience that reinforcement is absolutely necessary when the winds come. I'm thinking chicken wire will give the plastic the protection it needs from the wind. My concern is mostly that I might have to replace the plastic midway through the season due to sun and wind.
 
This is my first attempt to build a greenhouse. Opinions and ideas please. What else should I do?
 

 

I'm from the central coast in California. Midway between Los Angeles and San Francisco. Lot of fog here.
I've already started the frame part. I'm trying to convince the ol'lady we need to buy a roll of plastic and a few tid-bits to make it happen. I am working with a "0" budget so it won't be an overnight project.
I'm using this frame because I already have it, but it's way bigger than I wanted the greenhouse to be. I mainly just want to see how it's going to work out at this point. If I see favorable results and potential for improvement, then I'll go balls out for a green house for next season.
I currently have two - 2 1/2 month old plants, two - 2 1/2 week old plants, all from seeds, and I just dropped 6 more seeds into starter cubes. These are all destined for the greenhouse once I get it built. Still gotta see how many females I end up with.
I also have a bathroom full of females that are on day 66 from the start of 12/12 using CFL's. So I hope to be cutting and drying in a few weeks.

 

Maybe this post will answer your question about temps.
http://forum.grasscity.com/greenhouses/1284047-greenhouse-what-i-need.html
 
I ended up growing inside over the winter due to temp and humidity control issues. I have a dehumidifier running, but it quit about 2 weeks ago. I found one on craigslist that was almost new for $45, so humidity control is up and running again. 
Not sure what to do about high humidity in the greenhouse when it comes time to flower. Vegging should be ok because I live in a normally damp area.

 

I thought I was buying clear plastic. At least that's what I read on the shelf, but maybe I grabbed the wrong one? This stuff looks more white-ish. Am I ok to use this, or will it block the sunlight? 
It's 6mil sheet, I can almost see through it kinda.
 

 

I can see through the plastic in your picture. Is mine ok to use or will it block the sun out?
 
I totally agree with anchoring it. I used the wire stakes that came with the frame, but I also plan to fix a couple guy ropes as well.
I'm gonna have to add some type of support between the poles, too. There's just too many acres of plastic with no support. That wind is a mofo, man!

 

I saw that greenhouse on ebay. It's more the size I would prefer to have, but I thought the seller seemed kinda flaky. Some of the feedback stated he's advertising items he don't have. The listing said more than 10 available, but when I clicked on buy it now it says this item ain't available. WTF? 
 
So anyways, what do you think of that greenhouse? Structurally sound? Good material? Will the zippers still work next time?

 

New question about my "unfinished" greenhouse. What size openings should I make for ventilation?
It stands just a hair under 10 feet tall at the center, 6 feet tall at the sides, and takes up a 10 feet x 7 feet "foot print".
It sits on uneven ground, so the bottom is not sealed air tight, but that don't necessarily mean it will exchange enough air. I would really like to not have to use power, but will run a fan and supplemental lights if I really need to.
This is my prototype, figuring things out as I go. I don't know yet just how many plants I will end up with on this first run. I'm thinking at least 4 for sure - possibly 6.
 
The good news is, we had a couple of those hardcore windy days and the house didn't fly apart. Took it like a champ! But of course, the plastic ain't rotted from the sun and elements yet, either.
I stuck my four baby plants out there and been leaving them overnight and they seem to be doing ok.

 

Trying to come up with ventilation ideas, I did this.
 
It's a coffee can, cut the bottom out and put some screen in the opening. I trimmed a piece of another coffee can to fit inside and hold the screen in place like a snap ring.
 

 
I used one screw to secure it on top, and another screw to secure it to the side.
If for some reason I ever need to, I can snap the lid back on to stop the air flow.
 

 
I can make as many of these as I need to. I only have 3 made up at the moment but I have more cans and screen. I was planning to install maybe 3 lowers on one side, and 1 or 2 up high on the other side.
 
So what do you think? Should this work or did I just screw up my plastic green house?
 
(edit) This year is my trial run. I'd like to figure out what works and get all the bugs worked out. So that next year I'll have a good handle on just what I need to do.

 

That looks like some I've seen around. Good sturdy frame. If you get wind anything like we do here, you'll need some bracing on the sides to support the plastic.