A cheap shop light will do just fine. The fixture doesn't matter at all.

If you want, you can upgrade to a wide spectrum, natural daylight or grow light bulb in the cheap fixture.

However, for seedlings, that isn't really necessary, since they grow so quickly. The spectrum of light does influence plant growth, both in type and quality, but on a scale of many months. With something that's grown and gone into the sunlight in a few weeks to a month or two, it won't make much difference whether you use grow light bulbs or just plain old cheap cool white florescents.

The most important thing for seedlings is just keeping them as close to the bulb as possible without cooking them, and keeping the bulbs on for at least about 14 to 16 hours a day.

Thanks denninmi. You said the fixture doesn't matter, but then you go on to say that "...plain old cheap cool white florescents" will work. That was my main question. I don't have time/knowlege/patience to get into the correct wavelengths of the light needed.

But once the seedling have sprouted, is it REALLY necessary to keep them lighted (with the $15 white florescent) for that long (14-16 hours). That long?

Yep. That long. ;)

Dave

Yup, like Dave Digdirt said, that long, with a few caveats/exceptions -- some plants, like spinach and Chinese cabbage, will bolt to seed prematurely under long days, which isn't what you want, so they should only get about 11 hours a day.

And, actually, a lot of things, like corn, melons, tomatos, peppers, eggplant, grow fastest with 24 hours days - no dark period at all. If this were constant, it would throw their biological cycles out of whack, but for three or four weeks when young seedlings, it doesn't harm them and makes them grow faster.

Dennis
SE Michigan

More like 16-18 hours a day, I'd say. Remember that sunlight is much stronger than fluorescent lights, which are closer in intensity to light shade, so you have to compensate with more time.

I didn't know some plants bolted with long days as Dennis says  I'd like to find out more. But last year I started spinach early and kept everything on long days, planted it out in April, and it didn't bolt until the weather really heated up.

It's important to "harden off" your seedlings once they're ready. This means gradually acclimating them to wind, sun, and temperatures outdoors. Start by putting them out for a few hours in light shade or filtered sun on warm early spring days, and gradually increase the exposure.

Row covers are a great, easy way to provide the shade and warmth needed for hardening-off. Cold-hardy plants like spinach, lettuce, and beets can go out "as soon as the ground can be worked." Cover the whole bed (weight down the sides with rocks and/or ½" rebar) and come back in a couple of weeks.

Warm-weather ones like tomatoes, cukes, and squash shouldn't go out until the soil is at least 60° or so and nights are above 50°. For those, I found that acclimating them to strong sunlight is the most important part of hardening off. This year I built little open-sided tents for the seedlings from garden stakes and old sheet fabric. After a week or so, I changed the fabric to row covers and after another week removed that. It worked out well and was easier than moving the seedlings in and out every day.

Less is more when it comes to early starts. Plants should usually be about 6 to 8 weeks old when planted out. If they are older they adjust more slowly outdoors and may grow spindly under lights. There are exceptions though, like celery and leeks, which like an earlier start. Your seed packet (and usually the online catalogue) will tell you optimal seedling-start and planting-out dates for your area. County agricultural agents, or gardeners' Web sites like Cornell's, are a great source for this kind of thing. All good vegetable gardening books also have this information.