Plastic sheet for greenhouse

Question

I'm trying to build a DIY greenhouse and have a question about the plastic sheeting.

I see that no one is using clear plastic - it's almost always translucent. Is that on purpose or just that the very clear plastic sheet is not available on large scale.

I was planning to purchase this 3.5 mil clear plastic sheet for my DIY greenhouse (to be built on 1st floor patio (5ft x 5ft x 5ft)) in Cupertino, California (Hardiness Zones 10a, 10b and 9b)

Does this plastic sheeting looks good or should I find something really clear plastic sheet like in this photo?

Any ideas & feedback much appreciated.

Cheers!

Answer 1

With greenhouse plastic there are some issues to keep in mind. First, if you are considering a longer term installation then UV light will quickly shatter regular plastic. UV resistant plastics are available. Even then your max lifetime is about 4 years. The second issue is abrasion. With expansion and contraction of the plastic sheet the plastic cover is almost always loose and responds to wind and even light gusts. This rubs the plastic against the frame. Again, for a longer term project a thickness of 6 mil is much preferred; 3.5 mil is very flimsy. Translucent may well be good enough for the plants; if perfect clarity is highest on your priority list, then go for the clearest you can find but be prepared to replace it frequently.

Answer 2

I used clear plastic, but it became translucent in one or two years.

On many climate, clear plastic (and clear glass) is too much in summer. Translucent is often a good compromise for winter and summer seasons.

Translucent has the advantage that it diffuse the light, so there is less problem on putting more dense crops (space in greenhouse is more restricted/expensive). I also think that we care much more about 'greenhouse effect' and not about amount of light (screening the outbound light and heat).

Answer 3

Mayank I've used all kinds of plastics including the cheap stuff. I finally purchased the correct plastic for the skin of a greenhouse. This is warrantied for 4 years. The cheap stuff disintegrates within a year. It will fall apart in chunks or if you've got snow, your green house will implode.

The 'good' stuff has at least a 4 year warranty against UV damage. This is the minimum you want to purchase and use. The plastic you are considering isn't made for green house skins or any exterior application where the plastic is harmed by sun. The good skins are a bit opaque, not clear.

Installation of this plastic is another issue for longevity of the 'skin'. 4 years is very nice but still a short time. Installation is critical. You have to use 'padding' beneath the plastic above the structural members and then you fasten that plastic using proper screws with 'skirts', round gasket like things so the plastic doesn't tear. Make sure you know which side of the plastic you purchase that is meant for a greenhouse is supposed to be UP facing the exterior of the greenhouse.

Don't use the cheap stuff or you shall have to learn what we all had to learn the hard way. Just saying! Skinning a green house is a LOT of work. What kind of greenhouse do you have or are making? What zone do you live? Are you using the garden soil in place or are you doing pots? Will you have artificial lighting? Make sure you have big fans in place to run 24/7 during the season.