Don't use it. If you want to know what happens to it after a few months. Go buy a roll, unroll it in the front yard and run over it with the lawn mower until it is all chopped up. Yes it is cheaper than greenhouse grade plastic, but that is the only plus side. After 3-4 months it starts to get brittle and breaks. It rips easy and has to be replaced. It doesn't have the UV protection that greenhouse grade plastic does. Also, the greenhouse plastic has a 4 year minimum life span. Also it resists ripping. The stuff is tuff! But this is only my experience. You do the math, replace your plastic every year or every 4 years?

jrslick - thanks for your reply. Based on the info you provided, I think it will work for my application - and here are the reasons:

1. The "greenhouse" is only 4x4, with a peak height
of around 6 ft. The frame is made with pvc pipe.
2. It will only be used for approximately 2 months
during early spring (mid March - mid May)to help
harden off tomato seedlings as they outgrow the
constraints of the propagation chamber.
3. After each use, it will be disassembled for storage
anyway, so new plastic will be installed every year.

What's your thoughts?

EG

It would probably work for that but over time, I would think that it would break down and start to get brittle. If you get a small piece I am sure it would work and it would be cheap. Although, if you are buying plastic every year, how much would you save by buying the greenhouse plastic and reusing it every year?

Another problem is with the PVC and plastic. Some people say they interact, I haven't seen this problem. I guess the PVC I have used is fairly old. I have spoke to others who also use PVC and Poly and they haven't had any problems and they say they get 5-6 years out of the poly. If there is an interaction it can be prevented by painting the PVC with latex paint.

I have 3 hightunnels with pvc and poly covering and I haven't seen any problems.

Jay

Jay - I can skin it each year with this stuff for about $13, and really don't know how I would store the special stuff anyway. It's gonna be a hybrid version of a greenhouse/hoop tunnel that is anchored to my raised bed. You can see a picture of it in the thread below.

EG

Here is a link that might be useful: Thread in sfg forum

EG,

I use clear six mil plastic on some windows during winter. This past spring, I got busy, planted a flower garden and forgot to take down a piece of it on a front window. This is a south-facing one that gets beat down by sun, wind, rain - all the things that should destroy anything. But a year later, it is almost perfect.

A 4'x25' roll costs $17. The person who talked my wife into buying it said he usually gets about four years from his, though he removes once the weather warms up.

Mike

Mike,

Wasn't your plastic protected by glass?

EG, as I'm sure you are aware, glass is considered almost completely opaque to UV radiation (partial transmission of UVa, but blocks all UVb). Therefore, his plastic did not degrade from UV light, as yours would. That is a completely different application than what you would be using it for. I think that it will be fine for the limited amount of time you are talking about, but be forewarned that Mike's experience may not be applicable to your application.

Best of luck, and keep us posted on your results. Personally, I am looking for an easier solution to my tomato seedling problem (indoor space, artificial light, air currents, etc.) If your project works, I think that I will be replicating it for Summer 2011!

eagles,

Mine is on the outside of the glass, in the weather. But it isn't the construction grade - I've seen it and it in not 100 percent clear. This is vinyl plastic and I have not seen it in rolls wider than 4'.

Mike

Mike,

In that case, it is quite impressive that it has stood up that well!!!

eaglesgarden - this will hopefully address the problems I had last year, once the tomato transplants got pretty big. They quickly became overcrowded in the homemade propagation chamber, and I didn't have anywhere else to put them.
My propagation chamber is kept in the shed out back, because let's face it - there's no way my wife will let me have it in the house, and there's really no room for it anyway. This miniature gh will hopefully perform well, especially under the circumstances. I bought a roll of the plastic from Lowes yesterday, and will skin it before the outdoor temps get below 22 degrees. (That's pretty much the borderline for broccoli)
Keep a close eye on my blog, because that's where i'll document everything.

EG

Here is a link that might be useful: EG's Blog

thanks!

i used the 6ml from lowes on my front porch to keep out the cold, had it there all winter and all summer(sucked for the heat, but it did keep all the wind out!), it didn't get all brittle, i have had some on my dinningroom window for the past 2 yrs, its just fine. i like using that stuff. i am going to go buy another roll of it for a mini green house or something like it LOL. south side of the house i want one!! **big smile** ~medo

Medo - thanks for your input. Did you ever get your GH up and running?

EG

EG; I am using clear vinyl like wordwiz does. It comes in 4x25 & 3x25 at the local fleet and farm. the name on mine is Wrap's vinyl-pane It is clear like glass with a few waves in it maybe too clear for plants.It is a lot like the vinyl in a tent or camper window, I have no idea how long it will last as storm windows. Oh ya I think it is 4 mil. I also really like it and am planing on using it for hoops or cold frames.

Curt:-)

Curt - that's good to know.I'll give this 6 mil stuff a try, and see how it performs in the early spring.

EG

EG

I covered two melon trellises (arches made from 16' cattle panels) this spring with the 6 mil plastic the big box stores stock in the painting/drop cloth section. I found out what other posters pointed out, the stuff isn't UV stable. However, the covering lasted long enough in the spring to get us through to warm weather, which, by the way, didn't come along until July this year. In the fall, we put a new covering over the trellises and extended the season another four weeks or so. I plan to reuse the stuff we folded up this fall when spring comes. I haven't decided if I'll buy another roll, but the bottom line is it helped us get melons in our very windy, borderline 5A (maybe closer to 4B) climate at an elevation of +6,000'. Almost forgot ... the couple extra tomato plants I put under the trellises grew like crazy :) Good luck!

mrs. b,

There's a large difference between the construction grade plastic and the vinyl plastic. I have the latter (it's actually four mil, not six) and it looks and feels far different than the six mil construction plastic I saw at a Painter's Supply shop.

Mike

mrs. b - thanks for your input. I might construct a greenhouse made from cattle panels for my wife, later. I'd love to see pics!

EG

Hi everyone. Last fall, I constructed a homemade greenhouse for my coconut palms and other tropicals in the backyard. I made it out of 1" Schedule 40 PVC, with door frames out of red cedar, and I covered it with two layers of the contractor's grade 6mil plastic. It worked great and kept the inside of my greenhouse plenty warm over the winter. The coldest it got down to inside the greenhouse was 40F on a morning that the outside temp dropped to 26F. All I had for a heater was a small electric heater bought at a garage sale for $7. I connected it to an outlet in the garage with an outdoor electric cord. I built it to be 8ft. x 15ft. x 9ft. and it has worked great and stood up to several severe thunderstorms. I ran two lines of PVC down the length of the inside connected to the door frames and covered the whole floor with about 2 inches of pea gravel to help hold it down in the wind and to retain warmth. All the base PVC was anchored to the ground with metal C clips and nailed with large 4 inch galvanized nails to the ground before the pea gravel was added. I also used black landscape fabric underneath the frame. The contractor's plastic does have to be replaced each year though, since as stated it only lasts about one season.

You're welcome EG. I'm afraid there isn't much to see. Mostly our half-finished painting projects.

The first picture was taken July 4 (2009). The chimney is to our neighbor's garage - not the cold frame :) I took the second picture this morning. There are 12-18" of leaves piled in there, so the clearance might look less than it really is. The trellises are ~6 1/2' tall at the highest point. Plenty of headroom for me, of course, but a little low for others. The bases are ~4' wide. I knotted strips of material over the welds to keep them from tearing up the plastic in the wind.

I know they aren't beautiful. I had a lot of fun with them, though. And, actually, there were kind of pretty with the vines covering the wire and melons hanging down. Having the fruit up in the air had an unexpected benefit. Those were the only ones we got for ourselves. Our corgi nabbed every melon within short-dog reach. Yup, he got all the low-hanging fruit :)

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Ok, thanks! I'll put some thought into how to keep the rough edges from tearing the plastic - it shouldn't be too difficult to deal with.

EG

EG: I built a greenhouse out of cattle panels. I used the smallest foam pipe insulation I could find. Since it is slit down the middle, I just put it over the panel and wrapped some black tape every few feet. Worked great.

Construction 6 mil works fine for an overwintering--at least in my zone--and the major drawback I have encountered is that it does block more light than the dedicated greenhouse film. It is stiff enough to hold it's shape after installation and IMO it's a good start to see if you would benefit from a permanent structure, or if you only need it for a couple of months as you say.

engineeredgarden

Here's what I used for a small greenhouse...
http://www.network54.com/Forum/616213/thread/1215730396/last-1215730396/Grow+lights%2C+greenhouse+and+garden+-+2008

Scroll half way down the page. I went to Walmat to the arts and crafts section. They carry three different thinkness of plastic in rolls. This plastic is mostly used for kitchen table tops. I used the thickest they had. The guage is not marked but I would guess 20mil. If I remember right the rolls are 54 inches wide and was around $3/running yd. it worked great for what I was doing. That plastic has been on going on since early 2008 and is holding up well so far but
it not out in the sun year round.

You said,
2. It will only be used for approximately 2 months
during early spring (mid March - mid May)to help
harden off tomato seedlings as they outgrow the
constraints of the propagation chamber.

Same here with ours. For what you are doing, 6 mil would work fine since your GH is small and you disassemble it each year. You would have to use a new plastic every year. ZIP ties would be good fasteners with the PVC pipe.

What I did was build sections and cover each one. I have a plywood floor on wheels, four sides and a roof that just sits on top..I take it apart and store when not using it. I used 3 100w light bulbs on a thermostat set at 60 and threw an old quilt on the top at night to save the heat. You can also use a hair dryer for heat. The quilt made a big difference. My idea was for the GH to hold a large number of plants with easy access without taking up a lot of space.

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Here is a link that might be useful: Fran's Garden

That is an EXCELLENT set-up :)

Thanks for sharing!

I have been using a 4mm Twinwall panel removable green house for a few years.

The GH is constructed with packing tape and Velcro so that it can be taken apart and re-installed quickly.

This is to eliminate multiple transplanting and hardening needs for seedlings. My plant get a very good head start every year.

It had gone thru many windstorms with no problem.

http://www.youtube.com/user/dcarch7#p/u/9/MzDqDBw_F54

dcarch