I am by no means an expert in lighting. I know about and have used different types of florescents like Cool White, Warm White, plant and aquarium, Gro Lites, and full spectrum lights (whatever they are).

With my recent seed starting trays I noticed something. I had a couple of cell packs, about a dozen plants sprouting and they still had the first two leaves on and were about 2" tall. Above them, 3" or so, was a 15" warm white bulb. To the left was a T12 cool white bulb in a smaller fixture. That was going to be a special area with a seperate light timer. Well, these little buggers were bent 90 degrees toward that light that I had left on for a day or so. They favored that bulb over the warm white that was closer.Ok, so I switched them to a new area with the newer sprial 13w bulbs. A strip of six of them and they get more heat from those spirals and seem to be doing fine along with the other seed trays I have on that shelf. The temp seems to hold about 75with the lites on and 65 for the six hours it is off. As you can tell, I am experimenting a bit.

Anyway, back to the three K's.

I stopped at a local big box retailer and looked at their florescent lighting options From what I could find on the bulbs and packages I found that it is confusing for sure. And they don't all have the full info on the package but here is what I found:

K lumens (Don't look that word up in the dictionary unless you have a masters in library science)

Kolor Temp (A K figure listed on most bulbs....Cool white has a higher K than warm whites...plant and aquarium lites have the lower lumen figure but didn't give the K value but I assume it is also lower)

Kost (Varies but seems to rise with pretty packaging/fancy names rather than lumen or K value?)

All the lights that I looked at were GE and that was the main brand that this retailer sold.

F30T12 36" Kitchen and Bath 2200 lumens 3000K $6.96ea

F40T8 48" Kitchen and Bath 2800 lumens 3000K 9.64 2pk

F40T12 48" Daylight 3050 lumens 6500K 9.64 2pk

F40T12 48" Residential lite 3150 lumens 4100K 3.86 2pk

F40T12 48" Ecolux 3050 lumens 6500K 9.64 2pk

F20T12 24" Sunshine Full Spectrum 875 lumens 5000K 6.24ea

F20T12 24" Kitchen and Bath 1275 lumens 3000K 5.97ea

F20T12-KB 24" Kitchen and Bath Ultra ------- ------ 5.97ea


So, what does all this mean? I'm guessing from the above the daylight bulb is what seedlings would get the most from. I'll monitor my spiral bulb plants and have enough trays with the same seeds/potting mixture and do a comparison. And, I stopped by a charity thrift store today and found 6 24" bulbs for $1 ea that are cool whites and two gro lites so to heck with the above retailer. The bulbs looked good/unused but I will test them out. At least they were not black or scarred on the ends so they might be ok.