The more immediate question to be considered relates to your use of the term 'seedlings'. If the term is used appropriately and the plants native to your area, trying to keep them viable over the winter indoors would be a decidedly bad idea. If the plants are species commonly grown indoors, you could probably get them by with that light, but a hooded 24" fixture with 2 bulbs that produce light toward the blue end of the spectrum (cool white) would be a better choice. The bulbs should be almost touching the plants. I regularly have plants that grow right up into the fixture between the bulbs & the hood.

Change bulbs frequently - output drops off very sharply in the first year of use. It's not unusual for bulbs to lose 50% of their output over a few month's use.

Al

Al, I have made a fixture that will hang over my indoor trees and has spots for three light bulbs. I can screw in the regualr threaded light bulbs (plan on using the new CFL kind)...what wattage or type of bulb should I buy that will be closest to the blue end of the spectrum?

I'm just starting them out indoors for the winter, once it's spring they're going outside, and any future winters will be spent in the garage or ground for their desired dormancy period. I'll try to find a cheaper 2 bulb fixture to mount where the current light is at.
thanks!

Ed - I'd use 3 - 23 watt (= to 100 watt incandescents) CFLs and try to rig something to act ass a reflector hood.

Joe - I really think you're heading toward disappointment if you try to over-winter the temperate seedlings indoors, but I guess that's all part of the learning process. Consider for a moment that Mother Nature makes no special provisions for her seedlings. They live in the same soil and tolerate the same temperatures as their larger counterparts. The garage idea is considerably closer to the plan she (Mother Nature) had in mind .....

Al

I have a reflector hood all rigged up that I made out of heat duct - silver stuff - Will get the 23's - thanks.