The only seeds that require darkness for germination are a few flower types.

Germinating under-lights is pretty much standard method for most all vegetables including tomatoes. While supplemental lighting is not required for germination some light sure is. And doing it under the supplemental lighting helps prevent leggy seedlings - ones that don't get moved to intense light immediately after germination.

Dave

LOL. Saves me a step next year then. I've always done it dark and watched it like a hawk - once they sprout, I get them under the lights so that they don't get leggy. If I catch them even a day late, they seem to get leggy the 1st day or 2 under the lights and then they settle in nicely.

Plants don't need or use light until the first leaves start to come out. Basically, almost as soon as they pop up. Light won't hurt anyone if the plants aren't up yet. It's pretty dark underground.

Yep, tomato seeds can germinate if there's light. It seems kind of like they like to sprout with the rising of the sun, as opposed to during the afternoon, during the night, or some such, however. I'm sure they can sprout at other times, but pretty much all of my seeds seem to sprout in the morning.

I've never tried germinating tomato seeds without light.

You can germinate tomato seeds with/without light, I've done it both ways.

(damp paper towel between two saucers, damp paper towel in zip-lock, direct-sow inside GH).

The question I've had for a long time now is, why would you want to germinate them without light? It seems like there's a fungi risk that way.

I'm not aware that fungi don't like light. Mushrooms grow fine in light, and fungi in general, while they don't photosynthesize, use light for internal biochemical signalling, and I believe light is essential for production of fruiting bodies.

Interesting.