The spectral distribution of daylight fluorescents and daylight LEDs are the same. So for the same amount of lumens, they are identical. You want those lumens to hit some number of square feet under the lamps where your plants are. Frosted bulbs will throw a lot of the light off to the sides, where it won't hit those square feet at all. In fact, LEDs without diffusers point the light mostly in one direction. Diffusers are the white enclosures around light bulbs. Fluorescents have built-in diffusers, and shoot light in all directions.

Bottom line is that LEDs are not only electrically more efficient, they send the light largely where you want it.

If you're just using the light for seedlings, the color of the light isn't going to make a big difference anyway.

Having said all that, I happen to like fluorescents, because when I seed my transplant pots in my converted garage in the winter, I want them warm. Fluorescents make enough heat to do that. If you don't need warmth, LEDs are more efficient.

Dan, thank you for the information. And thanks for correcting my assumption on the frosted/diffusers argument. Your point on fluorescents being warmer is well taken given my cool basement temperatures. The makes me lean towards fluorescents.

I actually have a large blanket that I drape over my fluorescents, with the seedlings underneath them. If the garage is cold, I drape it over all the way, and keep the temp under it at 70-80F-ish. If the garage is warmer, I pull the blanket up a bit. If the garage is warmer than 70-80F, I remove the blanket entirely. Get a thermometer and work accordingly. LEDs are great, but if I used them, I'd need a separate heater.

Great idea! thanks!