seedling growing lights

[TZ-OH6]

Dennis,

I really don't know. You would have to look at the technical specifications and spectral output. And compare that to wavelength absorption by plant phytopigments, but if it looks white to people it has green light the plants can’t use. Lumen output sums all visible wavelengths so the extra efficiency would have to overcome the wasted green wavelengths. Those lights are dual purpose, they have to provide healthy light for aquarium life (mainly corals) and also make the aquarium look good. But I do think the 54watt T5s are the best way to go for long term indoor growing of high light, short stature plants in a relatively confined area (I don't put tomato seedlings into this catagory though). Red-Blue LEDs would be the other option (more efficient, higher cost).


Once you get away from cool white-warm white fluorescents into discussions of high end lighting it gets complicated because of price. Do you want to spend money on more efficient tubes and ballasts or on electricity? Which will cost you more? Is it more than enough light for the plants you are growing anyway? What about the toxins and materials in the lights...is it better for the environment to just use a little extra fossil fuel via electricity? Then we can get started on reflector efficiency. At some point I just stop worrying about it. The point being where I can’t justify paying $100-$300 on more efficient lighting (in use for 6 weeks a year) for seedlings that I could get to grow with free window light if I wanted to work at it.

For me, shoplights with 6,000+K T-12 or T8 are cost effective for starting tomato seedlings. They are at the minimum for growing compact flowering orchids (It doesn‘t matter if my tomato seedlings are not quite as robust as nursery grown but it is a problem-failure if my orchids, which only flower once a year, don’t bloom, so they get the expensive lights.)

At the other end you are talking about permanently growing large plants indoors (vegetables, large orchids, marijuana) you need need high intensity light simply to make up for the distance dropoff in light intensity from the light source, and you are pretty much stuck with using hot noisy 400 watt MH or Sodium hybrid HIDs.
　
Red and blue LEDs are the most energy efficient in getting electricity converted to photosynthesis but initial cost evens out the lifetime electricity savings (or did when I looked into them a couple of years ago). And you are stuck having to use them for shorter plants (12" or so)because of the output, not to mention the ugly purple color if you want to look at your plants.


Metal Halide HIDs have probably the best spectral overlap with plant pigments for a “white light“ source, much higher intensity per unit area than fluorescents, and good efficiency, but heat production and sound are problems.


I have or had T12 and T8 shoplights, a T5 54 watt -8 tube unit, T5 curly 115 Watt bulbs, 250 watt MH HID, and 400 watt MH HID. Each have their pros and cons. I also have a spare room covered in white “panda” plastic to take advantage of the window light.

[Marko]

Originally Posted by TZ-OH6

Red and blue LEDs are the most energy efficient in getting electricity converted to photosynthesis but initial cost evens out the lifetime electricity savings

YES! LED is future, as I mentioned in other thread, plants really grow under LED lights, not just become leggy.
Last year I first bought one led panel and when i saw positive effect on onion seedlings I bought another one. These were grown under LED's, mid april, two weeks from planting time:

[amideutch]

Marko, who was your source for the LED's and what did they cost? Ami

[Marko]

First one I bought on www.ebay.de and second on www.ebay.co.uk since I couldn't find it more on german ebay. Price was ~35 € + S&H each.

[dice]

This page analyzes T-5 vs some other options:

http://www.advancedenergy.org/progre...5versusT8.html

(Note that the math is off on lumens per year per bulb cost in
Table 2. It lists a T-8 bulb at around a quarter of the cost of a
T-5 bulb, with a lumens output around 10% higher on the T-8,
yet shows a lower per lamp cost per year for the T-5. Lumens
per watt cost, at the top of the table, looks about right,
without getting out a calculator to check.)

It was interesting that T-5 optimum operating temperature
is much higher than for a T-8 or T-12. The T-5 HO bulbs seem
to be designed to replace metal halides in high bay lighting
(warehouses and similar).

(FAQ: the "T-digits" designation refers to eighths of an inch
in bulb diameter. T-12 is 12/8 inch diameter, or inch-and-a-half
diameter bulbs; T-8 is 8/8 inch, or a 1-inch diameter bulb;
T-5 is 5/8 inch, or a little more than 1/2-inch diameter bulb.)

[Duh_Vinci]

Marko,

The panels you referring to are something as such: LED Light Panel ?

Regards,
D

[Marko]

Duh Vinci,
Yes, exactly. Though mine are blue.

[dcarch]

Originally Posted by TZ-OH6

Dennis,

-------Metal Halide HIDs have probably the best spectral overlap with plant pigments for a “white light“ source, much higher intensity per unit area than fluorescents, and good efficiency, but heat production and sound are problems.-----------

Not necessarily true with electronic ballast.
Check this out:

http://tomatoville.com/showthread.ph...t=metal+halide

dcarch

[Marko]

Got new toy today, light meter and checked my lights at different distances:

LED 5cm/2in 5000 lux
LED 20 cm/8in 4500 lux
FLUO 5cm/2in 3000 lux
FLUO 10cm/4in 2000 lux
Outside (snowing, 10am) 5500 lux
Windowsill 3000 lux