hi Tanya,

welcome to gowning under lights.
It can be lots of fun, some times sad (when damp off hits, etc.); always has things old and new to learn;
and gives you a real sense of accomplishment when everything works well. --besides, it lets you choose what you want to grow and not what the greenhouses have brought to the stores.

Here's my opinions on your questions, beginning with the latter:

1) "grow lights." As strange as it may seem, these special, expensive lights are used to "show" the plant, and not to grow it.
We see colors because that is the spectrum (Kelvin temperature) that is reflected to our eyes. When your flower/plant is placed beneath a grow light, it looks brighter, more vibrant, because the grow light is putting out more of that color, to be reflected, rather than absorbed, for growing.

The 2' fluorescents should be okay if you put in at least one cool white bulb. What's often used for starting and for growing is a combination soft & cool white or two cool whites.

2) spiral florescent: I too have those lights. I use them in my house to make it brighter (get rid of the lower Kelvin) yellow light.

The spiral florescent claims to be daylight, which has a Kelvin temp. around 5,000 to 6,000 degrees. A light that gives off "sunlight," provides more degrees Kelvin, thus the plant has more spectrum of light to choose from for growth.

I'd be concerned, that at 840 lumens this is far too little light for the seedling to grow successfully.
Even with my 4', 40 wt fluorescents, that puts out 4,100 lumens each, and are in a double lamp fixture, I still have to keep the plants within 4" of the lamps, and on 16hrs/day to be successful.

To get that intensity, you'll either have to move the plants within an inch or so of the spiral bulbs or increase the number of bulbs.

However, with each bulb you double the heat it puts out.

My shop-light fluorescents can be comfortably touched, no fear of burning the plants.

My spiral florescent, after a few minutes are too hot to touch. That would certainly burn the plants.

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Conclusion:

I'd go with the two 2' fluorescents, changing one bulb for a cool white, or change to cool + soft, or two cool light, shop lights. Of course you could go to the much more expensive "daylight/sunlight/full-spectrum" fluorescents. Just make certain the combined Kelvin temperature is in the 5,000 to 6,000 K range and the lumens are sufficient.
--I often find that the full-range lights are much dimmer than a cool-white.

--of course you don't want to give the plant too much light.
If the leaves begin to droop, angle down, as if they are trying to hide, then they are getting too much light. If they are reaching up, they are getting too little.--

Hope this helps,
Bob

So much misinformation, Bob, mixed with the useful stuff. It might be easier to ignore the whole lot rather than try to sift out the good from the bad. I'll go through it in detail if you want, Bob, but don't want to clutter up Tanya's thread with it.

Total light (in lumens) is almost irrelevant. What matters is light intensity in foot-candles (= lumens per square foot). 840 lumens is quite sufficient for lighting a small area such as a couple of half trays. Three of them would work well for, you guessed it, six or maybe eight half trays. I'm assuming that your torcclight has a fairly efficient reflector that puts most of the light onto the trays. You might have to adjust the distance from the seeds to get the correct spread of light, 6"-10" is probably about right. Notice how the 840 lumens is produced from a very small area, much less than an equivalent straight tube. Compact fluorescents are good for getting high light intensity which means you can grow taller plants without the bottom leaves dying off and without them stretching. The downside is that the compact fluorescents tend to be less efficient than the same power straight tube so they cost more to run.

The 24" tubes are maybe 17W? About 1300 lumens? Notice you are getting a bit more light for a bit less electricity, that's always nice. But the light is more spread out, over two feet of length obviously. You 'll need to put the tubes right down close to the soil, still with a good reflector to send the light downwards, to stop the light spreading too much. You would probably want to use two tubes together on a single line of half trays. Straight 2' fluorescent tubes can just about provide sufficient light intensity to start seedlings, but you'll need to keep them adjusted just an inch or two above the top of the leaves. You'll probably find the intensity isn't sufficient once the seedlings get past about 4" tall, hopefully you can start moving them into the sun by then.

If you want to start more than half a dozen trays, I suggest you should move up to four foot fluorescents, you'll get quite a bit more light for your money. Double the length gives a lot more than double the light.

One cool white plus one warm white is often recommended, but given that warm white fluorescent tubes are often more expensive you could just use two cool whites, they will work just as well.

OK, more compost for the pile.

Just happened to be thinking about this very subject while setting up my seed trays/florescent fixtures in my basement. I have several short fixtures 13", 20", and a four foot one that goes across the top of the shelf area. I don't know if this one (one WW & one CW bulb) will do much but I can't put it inside so it will probably only do a single row of trays on the top shelf. No problemo.

While doing this my mind wandered to a bath light fixture I replaced recently. Had six globe bulbs in it. I wondered if the mini spiral bulbs I have would work. I now use them in ceiling lites upstairs. They are marked CF13EK minispiral. One in my hall has been on most of the day and nite and I just reached up and held the bulb. It was warm but not too hot to hold. It would not hurt a plant unless it touched the leaf for an extended time.

I think I will mount the 6 bulb fixture (about 3' long) above my top shelf and let the spiral bulbs (3" long) hang down. Then I can use the 20" fixture elsewhere till I can use my porch again. Next time I am at Menards I will look at a package and get more info on what they put out or maybe someone has that info?

I agree that the spiral compact fluorescents are not too hot to handle. I'll happily swap them out by hand, even the 30W ones in my small propagator. Of course, that would still likely be warm enough to damage plant leaves in contact for hours at a time, but then the light intensity right at the bulb is too high anyway. Compact fluorescents should be mounted several inches away.

Your's are probably a 13W compact fluorescent. You can use them for plant lights. The only issue really is that using half a dozen of them gives you barely more light than a single four-foot tube, uses a lot more electricity, lasts half as long, loses brightness after a thousand hours or so, and costs a whole bunch more to replace. Consider moving to a better setup if you plan to run the lights for more than a few weeks. Also, consider whether a 23W bulb would make more sense. There is little point choosing a compact fluorescent for high light intensity in a small space (which is the only sensible reason to use them) and then using a low power bulb which doesn't provide high light intensity :)

Okay, lots of information to process, but I am going to make sure I understand and explain my set-up. I grow mostly in containers and one 5.5' long by 2.5' wide by 3' high old style bathtub. I am only starting in one of the 72 pellet Jiffy 7 mini greenhouse trays. I am starting three pepper plants, 4 greenbean, leafy lettuce varieties, and the rest herbs (I've decided to landscape with herbs). I will be getting some patio variety deter. tamato seeds (window box romas and Red Robin cherry) soon. Yes, I know it is late, but I have a very long growing season, and tomatos love sun.

Back to the set-up. I have a small cheap white plastic shelf. I haven't attached the lights yet because I need to find some of that mylar that I have read about in other threads. I just don't know where to find it. I've seen sun shades made from it at Wal-mart, so I may just buy a few of those since I have such a small area. I have industrial double size velcro and that is how I'm attaching the mylar to the plastic and the lights to the mylar. The lights will be fixed position but I can raise and lower the seed starting tray by putting something under it to start and taking it out as The starts get taller. I almost forgot. This is all set in front of a East/Southeast facing window that gets a lot of light but only directly in the mornings.

The other plants that I am trying to keep happy are varying heights. Tomatoe, purple bell, crook neck squash, jalepeno, and lots of herbs that I just wanted a jump start on for cooking purposes (I am so impatient). So the question is, will two lights per 24" shelf, with mylar behind it, sitting in an East/Southeast facing window, be enough? I don't know if they are cool white or warm white, but I can experiment with that to figure it out. The bulbs are RB17T8GL but the lamps themselves have a 20Watt capapility as stamped on the back of the fixture.

One other question, the lamps have diffusers around the bulb. Do I need to take that off? Thanks again.
Tanya

Hi,

Do compact fluorescent floods "run hot" to the same extent as the mini-spirals?

Anne

And on another note - make sure the fixture is set for the type of bulb you want. I just got off the phone with Philips and they indicated that the 1 inch fluorescent tubes are not compatible with the fixtures that take the 1 1/2 tubes. The ballasts are not compatible and will greatly decrease the life of the bulb.

jill

Anne, the floods will feel a little cooler because they are pretty much the same thing but with an outer glass envelope. You can only touch the envelope, not the tube itself.

Jill, Philips are partially right but are mostly covering themselves, maybe even trying to encourage you to buy more hardware. T8 tubes will operate safely in T12 fittings with a compatible pin arrangement (and the same tube length). The tube life will not be measurably decreased, but the T8 tube will almost certainly run about 20% brighter than spec (details depend on the exact ballast design). You won't be able to insert tubes with an incompatible pin arrangement, don't try to force it because they most likely will not work at all, may damage themselves or the ballast if they do work, and could be a fire hazard. Also be careful that a T8 tube is secure if you use it in a T12 fitting since the end caps or clips may not be designed for such a thin tube.