Grow lights, heaters etc, on a budget

The information I gleaned that diamond pattern Mylar was the best stuff came from giant onion growers using T5 lights.

 

No idea.

And that doesn't help in getting to the bottom of what's the best stuff to line grow boxes with as I was going to suggest that those of us with light meters, like myself, stuck some temporary linings around their grow boxes and posted the different lux readings.

 

I'm sorry my observations didn't help you

 

Personally I'd put both panels in the same cupboard that being the case. Unless you wanted to keep half the 'floor space' as a sort of dusk/dawn zone, but I'm not sure if that would serve any practical purpose.

 

FC, having successfully germinated the odd 100 or so seedlings in these e're light boxes,
what?where do they all go next?
ie - until it's warm enough to let them out into the big O ?

Jenny

 

Does your light meter register lux readings from any other LED source? Seems rather weird to me as cameras with light meters register LED lights and my light meter registers the light from my LED head torch.

 

It picks up daylight well enough. Its a cheap one though, so it wouldn't surprise me in the least if it was blocking out parts of the spectrum. Also, even with an accurate meter, the reading would be low from LED grow lights because the light level is comparatively low. The reason they are still effective is because unlike most light sources, LED ones are very narrow bandwidth, specifically the red and blue used in photosynthesis.

If you measure the light from more conventional lamps, you will get a much higher reading because you are getting light over most of the spectrum, including the greens, yellows, blue, violet etc that plants make no use of. See the (annoyingly animated) chart here:

http://www.botany.uwc.ac.za/ecotree/photosynthesis/spectrum.htm

Notice there are two distinct peaks in photosynthesis rates as you move through the spectrum. One very significant peak in the red, and one similar but much narrower in the blue. The LED panels exploit this by only having red and blue LEDs at those specific wavelengths. LEDs can achieve this precision because of the way they work. Most light sources exploit the fact that heat = light, so if you make something heat up to a certain temperature, you'll get light. You'll also get masses of useless infrared (to varying degrees depending on the type of light), as well as other parts of the spectrum that are of little or no use to plants. LEDs work on a different principle. They work on the principle that when current flows through two dissimilar materials (semiconductors), the electron orbit on the atoms is disturbed and photons are emitted at a very, very specific frequency depending on the nature of deliberately introduced impurities. So there is no wasted infrared, ultraviolet, green, or any other unused part of the spectrum. It means that although the light level is comparatively low, it is made up 100% of useful light for photosynthesis.

 

You could always tell the missus that they need a day and night zone so you need two cupboards.

 

I said that to my missus and the reply was "anymore cupboards/boxes in the house and you'll be living in one! "

 

It might be interesting for those of us with light meters to checkout the lux readings at various distances from the various lights we have and those such as myself with diamond pattern Mylar could compare results against kitchen foil, etc.

 

Me too, makes no logical sense to me, but I've seen it quoted on 'tinternet lots, so assume it to be correct. However, having some peer reviewed / published science would persuade me more. I'd also like to know why Kitchen Foil is not a good reflector. It might be as C1 says because it is focused, rather than diffuse, but [maybe I'm alone in this] if it was just that I am inclined to think that that would have been stated as the reason in one, of the many, articles that I have read on the subject.

I'll get my daughter to ask her GCSE Physical teacher

Sorry, I have not fully grasped what the question is here - probably wasn't paying attention to an earlier post, sorry. FC : Do you have two LED panels? if so I would put them side-by-side so that any spilled light was shared by adjacent seedlings, and so that when only using one (not very many plants at that point in time) and then when rearranging them "for more space" or whatever, if they expanded sideways you could then decide to turn the second one on.

But I may be answering entirely the wrong question.

Personally I germinate my seedlings in the dark, or in "room light only", and once germinated they go under lights. Later on, in the Spring, I use the lights in the conservatory to extend daylight by 4 or 5 hours a day - light hung over the plants so that they still get daylight, but then also get supplemental light.

I wonder if putting a, say, blue filter under the lights (whether LED or Broad spectrum) would enable a reading with a light meter that was comparative? (and then repeat with a red filter)

 

I came up with another theory. Would light meters pick up infrared? Foil is transparent to infrared, whereas paper is reflective to it.