lachase,

You will probably do just fine by buying the least expensive fluorescent tube. The old standard "cool white" bulbs, although poor for vision, were excellent for plants. Their coating was a halophosphate blend, while the better, newer lamps are tri-phosphor blends which have spectral peaks close to the 3 color receptor cones in your eye. Luckily for us, both the halophosphor and tri-phosphor types have a wide bluish peak right where the chlorophyll wants it. The red is a bit lacking in the halophosphors, but the tri-phosphors do have narrow peak NEAR the red chlorophyll receptors absorption peak. Unfortunately, most of the fluorescent lamps sold as plant lights simply use the same red phosphor as the tri-phosphors, which peak at 611nm. One exception is the GROLUX Standard (not the Wide Spectrum)which uses magnesium fluorogermanate to peak at 658nm - a much better red.

For the most part though, you get better value, and as good a light, by buying the less expensive bulb. Most all of the CFLs on the market are tri-phosphor, but some of the fluorescents are halophosphor/tri-phosphor blends. A tube that says 741 or 735 or 730, for example, have a halophosphor coating against the glass, then a tri-phosphor coating over that. That is the best of both worlds. The lamps that say 841 or 835 or 830 are all tri-phosphor and are a bit better for your vision than for your plants.

One totally unnecessary thing people do is mix the "cool" lamp colors with "warm" lamp colors. There is NO difference between using a "daylight/warm white" combination and just using 2 "cool white" bulbs. Once, I used a published spectral breakdown of light energy output, separated about every 30 nanometers, or so, for a large variety a bulb types. I added the watts/nm (how much red, how much blue) for various combinations and found mixing lamp types was no different than just using a median color temperature bulb.

I find the questions being asked here to be repeats of conversations that took place here years ago. About 3 to 5 years ago practically EVERY POSSIBLE aspect of lighting was seriously discussed in detail, covering many hundreds of topics and thousands of individual posts. So many of the current posts were totally and exquisitely covered. Too bad I do not have the time or energy to devote any more. We once did cover EVERTHING you could possibly ask.

Also, "full spectrum" is a very well-known marketing term with no real definition except to sell lamps for ANY purpose they can get away with. If you look at published spectra(SPDs), fluorescent lamps are very spikey - all peaks and valleys. On the other hand, incandescent lamps and candles are very much "full spectrum" by reasonable definition. Just shows how you are being sold a false bill of goods.

Sorry about the rambling, but there is so much to know, and it was all covered in great detail in the past - everything anyone ever asks here lately was better explained back then.

Beware of the salesmen here. We now have several in this forum who are seriously misleading people.

Zink