Supplemental winter lights
Steve Marak via pbs (Sat, 26 Feb 2022 10:44:11 PST)
Hi Ken,
That is a rabbit hole, as the lumen unit is biased for how our eyes
respond to light rather than how plants do or the power distribution of
the light. (Your careful wording suggests you're aware of that!)
I Googled the BML SPYDR, since that isn't one I've used. It's clearly a
high-end unit with a lot of careful design and attention to detail
behind it. I particularly like that they under-drive the LEDs; LEDs can
last for many years if not run too hot but a lot of cheaper fixtures do
that to cut cost.
Where I use artificial light, it's the primary source, so I can't help
much with it as supplemental lighting. As Leo mentioned, unless you use
long-life fluorescent tubes, which cost more, their light output will
decline quite a bit, often within a year and nearly always within 2.
Long-life tubes hold much more of their rated output much longer, but I
still prefer LEDs. Distribution is also important when considering a
single higher output fixture vs 2 or more lower output. None of which
addresses your question about amount of light in lumens, of course.
Best to measure, if you can. If you have access to a PAR meter, measure
the PAR flux you have now, which is clearly working, and then attempt to
match that when/if you have to replace the fixture. If no PAR meter,
well ... the purists will be outraged, but I'd just use a cheap meter
that measured lux/lumens to get a base reading on what you have now. Not
the data you really want but I don't think it's completely useless either.
Plants are amazingly good at harvesting photons across the visible
spectrum, even green ones (related geek content below), and my personal
experience is that as long as the color temperature of the light is high
enough (because that ensures there's some up in the blue region),
there's considerable latitude in what works, even if it's not precisely
optimal - which is what I'd expect. High enough for me is 5000 K, though
I prefer 5500-6300 K. As Leo also pointed out, color temperature as we
use it for artificial light sources doesn't mean the spectrum is what a
real physics black body at that temperature would produce - that's
another rabbit hole - but I haven't found spectrum to be an issue either
except in a few fringe cases.
Sorry about the length, and that I don't have better advice.
Geek content - I stumbled on this fascinating article a year or so back:
https://quantamagazine.org/why-are-plants-green-to…
Steve
On 2/25/2022 1:43 PM, Kenneth Preteroti wrote:
Steve I appreciate your comments and the comments sent to the group
and to me privately. I accept that the cost to benefit ratio of high
end LED’s is not reasonable. I will continue to use my old BML lights
(I believe they are equivalent to a 600 watt metal halide not 1000
watts as I previously stated) to supplement the sunlight in the winter
months. When the BML lights fail I will look to purchase economical
lights.
One question which is the rabbit hole you may not wish to go down.
Using lumens as a measuring unit (because that’s what is printed on
the shop light box and fluorescent bulbs) a 2 bulb 4’ T5HO 108 watt
fixture puts out 10000+ lumens while the 2 bulb 4’ 40 watt shop light
puts out 4000+ lumens. What are your thoughts on the amount of
supplemental light?
Ken P
New Jersey, USA
Zone 7a
The past was erased, the erasure was forgotten, the lie became truth.
George Orwell, 1984 <https://www.goodreads.com/book/show/5470.1984>
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