Lights - 'grow' lights, 'full spectrum' lights, 'daylight' lights

lizfm(9)March 10, 2008


Since we live in a townhouse and have no useable windows (we have 2 full-light Southern windows [in Arizona no less] and 2 northern sliding doors onto covered patios), we have gone the light stand route. Plus the cats have staked their claim on the South windows and the violets would not survive being sprawled on by an 18 pound Maine Coon ;o)

We did not have space for a 4 foot stand so went to Home Depot and found a nice tall one that's 3 feet wide. This will let us have 3 shelves with lights. The minor downside is that you can't find shop lights in 3 foot lengths but hubby being a farm boy knows how to hard wire stuff so that was no problem (for me at least, he grumbled a bit).

We have three 3-foot light fixtures. Each takes two T12 lights. My question is, do "grow" lights come in 3 foot T12s? And what exact catchphrase am I looking for, when looking for bulbs? I am a bit hesitant to just look for "plant" lightbulbs as one that I took a closer look at, was just a colored bulb that made plants "look better"...I definitely want more than looking better.

Can somebody give me the 'dummies guide' to flourescent light bulb terms?? Thanks!

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paul_(z5 MI)

Hi Liz,

I can't remember the sources (read/heard this from several) -- though I believe the "Growing under lights" forum was one of them -- that the last 6" of tube on either end actually is rather useless for growing most plants (something about the intensity perhaps?). So having 4 ft shop lights over your 3' shelves would actually give you the use of the best part of the bulbs. Btw, in my experience you will want bulbs that are at least 40W.

Grow lights are generally expensive and not what they're cracked up to be. Now I have heard that lights made for growing corals are excellant though expensive.

For AVs and orchids I've found a mix of cool and warm fluorescent bulbs to work just fine. Presently, I still use them on my plant stand [which happens to be 4 ft]. However in my terrs I use cfls. AVs flowered fine under them too.

    Bookmark   March 11, 2008 at 6:32AM
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I also grow on a 3' wide rack. I use a two-tube 2' T12 fluorescent fixture mounted to the underside of a shelf. Both tubes are 20 watt T12 OTT-LITE indoor plant grow lights. All of this was bought at Home Depot (*some assembly required). I don't recall any 3' T12 tubes.

I prefer having a 2' light with 6' on either side. I use the sides as a secondary, less intense light for AVs that don't seem to like being directly under the tubes.

I agree with Paul that cool and warm tubes work fine, but the ott-lite tubes were only a few dollars more.

Here is a link that might be useful: OTT-LITE Technology

    Bookmark   March 11, 2008 at 9:29PM
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Sorry, that was supposed to be 6 inches on each side, not 6'.

    Bookmark   March 12, 2008 at 7:17PM
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korina(9b, Sunset 17)

Yep, I have a 3' wire shelving unit from Target with 24" fixtures (two 18w cool white tubes each). I also use the ends with their less intense light; some plants seem to prefer it. The trick is working out the proper distance from the bulb to the tops of the plants. Start at 10-12" for standards and go from there.

Good luck and happy experimenting!


PS For a thorough discussion on the subject, go to the AVSA site and buy a copy of Pauline Bartholomew's Growing to Show. It's an *invaluable* resource for growing AVs.

    Bookmark   March 16, 2008 at 1:25PM
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Hi Liz,
Since I have been growing for over 25 years I have found that the 4' fixture is best for my plants and also the most economical. When I was working and could afford them I used Varilux bulbs which I found gave the plants a great growth rate, however, they are expensive and cost retail over 12 dollars each. Since retiring I switched to 40 watt cool whites which I purchase by the box at Home Depot or Lowes. They work well and give me no problems. I have on occassion in the past used Gro-Lux and Gro-Lux WS. Both bulbs give good growth to the plants and make the plants look really beautiful and healthy under the light. But when you remove the plant from the light into natural light there is great disappointment. They loose their color and look rather ordinary. The Gro-Lux WS bulbs were always cheaper than the Gro-Lux. Many people prefer to use one cool whit and one warm white to grow. Since I cannot find warm whites I now use cool whites exclusively.
Hope this helps.
Fred in NJ

    Bookmark   March 16, 2008 at 4:25PM
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I too haven't been able to find bulbs labelled 'warm white'. However, there is a 'daylight' bulb that had a different hue than the cool whites, and I assumed it was a 'warm white' since it has a warmer tone. I got them at either Lowe's or HD, don't remember which. I use one of each, and they seem to do fine.


    Bookmark   March 16, 2008 at 7:26PM
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Warm white may also be labeled as "soft white". It has a lower color temperature ~3000K and looks redder than cool white ~4000K. Real sunlight is from 5500K to a 6500K peak at noon on a clear day. This is mostly based on the color human eyes see or perceive, which is not directly related to the spectra plants need for optimal growth.

Here is a link that might be useful: Color Temperature

    Bookmark   March 17, 2008 at 8:17PM
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