We purchased 4mil polyethylene that was supposed to be 'clear' but it is opaque white. We can not see through it at all. Is this normal? Will this work for one year?

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    I purchased some plastic sheeting that is specifically made for greenhouses. It said it was clear and I received it clear. If you didn't get what you ordered return it. You can see a picture after installing it here organiclawndiy.com/2013/10/winter-square-foot-garden-2013.html After 1st day the heat under the plastic caused condensation to form and it didn't look clear from then on. As far as I know there aren't any plants designed for growing in greenhouses. Greenhouses are designed to control the environment. Find plants that do well in the environment you created. Too many ?'s May 13, 2014 at 5:33
  • You'll be lucky to get 6 months. Semi-clear polyethylene photodegrades quite fast from ultraviolet radiation. May 13, 2014 at 21:10
  • 6 months...I want vegetables now! Grin. I'll watch how these plants do...be able to tell if they aren't getting enuf light. 6mil looks clearer...that is what is on my tiny greenhouse. i called and there is no mistake this is what you get for clear 4 mil. Two boxes we bought of this stuff, two different companies...both opaque. The uv resistant stuff is twice as expensive and I am going to replace it next month with the more expensive. Weird, clear is clear and opaque is not clear.
    – stormy
    May 14, 2014 at 20:18
  • All sheeting has some amount of light loss and distortion but you should be able to identify object behind clear sheeting. Here's some 4mil sheeting from Home Depot. homedepot.com/p/… a product picture of it covering a stack of wood. Not perfectly clear but I would consider that "clear". If light gets through it's not "opaque". I think some people have white and black sheeting and they call the white sheeting clear and the black opaque whether the white is actually clear or semi-opaque. May 14, 2014 at 23:41
  • Had an early heavy snow last fall, October? Completely imploded the hoop house! Opaque plastic sheeting is cheap it worked sorta kinda for a coupla years but we've found the 'better' stuff...Sun Shield. Expensive but we had to rebuild the greenhouse with wood posts, beams...etc. Next is heat. This place is such a weird place to grow anything...90 degrees in the day and below 30 at night (F)...Fiasco, we kinda beat 6 months but your advice is sound. One gets what they pay for.
    – stormy
    Jun 30, 2016 at 5:02

1 Answer 1


It depends on your environment and how much light is blocked. Basically opaque plastic might even let 70-90% of light true even though you can't see through it. This depends highly on the plastic. If you're in lowlight environment then that would be bad but if you're in environment where you have enough or too much light then this should not cause problems. It all comes down to what kind of plants are you growing and how much sunlight you receive.

EDIT: Usually manufacturer has the data about light passthrough. Photographers light meter will help assess the amount but spectrum is different thing and you just have to hope the plastic cuts everything evenly. Also photographers light meter is adjusted so that it takes into account the light that humans see so it's not good measure on how much plants actually get as these are different spectrums.

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    How can you tell how much light and spectrum are coming through? Does a photographer's light meter register both?
    – stormy
    May 22, 2014 at 22:32

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