Be good to have this over on the Growing Under Lights forum too as everytime one of us posts the recommendation for 16 on and 8 off, there some there who consistently argue that 24/7 lights on from day 1 is the only way to go. ;)

Dave

I'm currently doing 12 hrs on and 12 hrs off with excellent results. I have observed plants that were under 24/7 light to have significant problems with root expansion and overall growth.

DarJones

I have been using regular shop lights (fluorescent)to start seedlings for some years with good success; I observe certin rules gleaned from the wisdom and experiences of contributors to this and other forums both formal and non tech.
1. Use a good potting soil
2. Apply heat to the bottom for germination
3. Maintain proper moisture.
4. Using ordinary fluorescent lights, I expose seedlings to 14 hrs/per day with lamps as close to plant tops as possible. I also build reflectors from cardboard and foil on all sides of the seedling set-up.
5. Transplant when you have two sets of leaves AND the plants look heaalthy I transplant to a three inch pot. Type of pot is up to you. Many have had success with different containes. At this point it doesn't matter much.I use Neptunes Harvest here.
6. An area of recent research to look at is the temperature which best enhances seedling growth, future fruit set, plant health etc. Commercial growers are looking carefully at this and we home gardeners might invest some Feb. down time googling some of the work done up until now. My unheated cellar is between 60-65 in April when I start my matos and other veggies and seems to be just right according to the very tentative studies done up until now. Would love to find out if anyone finds further inf0.

Sconticut

"Another article, (Mancellini, 1968) talking about germination, mentioned that cool white flourescent lamps delayed germination and incadescents inhibited germination.

I use cool white lights for my seedlings.

A college professor of mine, Mira Zussman, once said that the best question you can ask is, "so what?" So, I'll ask it here. So what? What difference is a few days or hours going to make? I know for a fact that the delay is insignificant. My tomatoes just germinated this morning in...drum roll please...five and a half days! Honestly, the added warmth of the lights in the confined space I have them mounted more than offset any retardation of germination that may have occurred.

As far as the 16-hour photoperiod is concerned, I don't know enough to reject or accept the theory. But I'm not taking their word for it. I don't do 16-hour photoperiods simply because they're not required.

Scott in Napa

sconticut, the best book I have found for what you describe as the "Cold Treatment" for growing seedling plus photo light periods among other topics is explained in detail in the book "Greenhouse Tomatoes, Lettuce & Cucumbers" by S.H. Wittwer & S. Honma. Don't know if it is still in print. Hope this helps.

The "sow what" is that better cared for, less stressed plants ultimately do and yield better.

Much like a child getting a better start. It's not that they wont grow or not produce, it is just that they have a much better chance to do better.

One word, "Phototropism"

Not sure if this changes anyones mind but I just germinated mine in complete darkness and had first germination after 2 1/2 days and virtually all after 4 1/2.