Greenhouse polycarbonate colours and light transmission

[El Presidente Hillbillios]

Hey Peoples,

Im working out a plant to build another greenhouse and am looking at polycorbonate for the roof and partialy walls.

My questions is, this polycorbonate is available in diffirent tinted colours, white, bronze, smoke and green. Would this effect plant growth? is full spectrum, ie clear the best?

[Bert&Ernie]

Seems like white or just clear would be the best.... they are the only polycorbonate ones ive seen.

[dajindo]

I guess this polycarbonate acts like a filter. The color of the filter tells you what color goes through. Other wavelengths are absorbed. For example red filter passes only red light.

And you want most of the useful light.

Since plants can't use green light for anything, green would be the worst.

I guess the clear one passes the most of the spectrum so it probably is the best.

Hope that helps.

[Anodyne]

You'd probably want to get the specs from the manufacturer as they're all gonna be different. Some colours will block more heat than light or vice versa (see pic), clear lets thru most everything, and they all block UV. Depending what you're growing & how the greenhouse is sited & ventilated, clear may be too bright/hot for some delicate plants? If it's a big space & it's only some of the plants you can just have one shadeclothed shelf for seedlings or something, but if most of the residents are sensitive you may prefer some more diffuse light.

[incognito]

I remember an old tafe teacher saying the purple? Coloured sheeting is the best? (And most expensive) as it filters the light to pretty much the spectrums that plants need?

Make any sense plant nerds?

[Sallubrious]

I wonder how you'd go if you made a few comparisons with a digital camera. Take a photo of the sun through a sheet and the histogram should give you something more solid to go on than speculation. Some colour sheets might let a lot of light through but if it's filtering too much red or blue it could be an issue. Others may filter a large percentage of overall light and heat and still let the red and blue wavelengths get through.

Just rambling......

[Yeti101]

Been wondering the same thing - need to re-roof the greenhouse after if got trashed in the storms (and transform it into an outdoor semi-entertaining area at the same time)

[Sallubrious]

It's pretty easy to knock up a spectrometer/spectrograph from an old CD or a piece of diffraction grating. I've got a few diffraction grates kicking around somewhere. It won't show luminous flux but it will give you a good insight into the spectrum the sheets let through.

[Anodyne]

yeah the product specs often just group the wavelengths into infrared/visible/UV, without a breakdown within these ranges, so you may not get detailed info about the visible wavelengths, red vs. blue etc - always worth asking manufacturers directly though, they might not publish all the more detailed specs on their website.

That CD spectrometer is cool!

[dajindo]

I remember an old tafe teacher saying the purple? Coloured sheeting is the best? (And most expensive) as it filters the light to pretty much the spectrums that plants need?

Make any sense plant nerds?

makes sense.

if the full spectrum is: red, blue, green.

take away the green, which is useless to plants.

now we got red + blue, which is purple.

[incognito]

I think the colour of the sheeting is violet or indigo