Hi Patty! I'm only a novice gardener, but so far I've been having pretty good luck with my
seeds.
As far as light, I would think that you would only maybe need some supplemental lighting in the evening for a few hours after the sun has gone down.
Your main concern would be the heat-what are the temps during various parts of the day/night? I know that for vegies, the lowest nighttime temps are anywhere from 45-60.
flowers I would guess would be about the same, maybe a little bit lower.
That's for already sprouted
plants. To germinate, I put my vegies on a heating pad, but not my
flowers, although they're above a radiator, so the coldest they ever get is about 60 degrees.
As far as individual
seed requirements, it really varies depending on the
seed. Most vegies do NOT need light to germinate. Lettuce, on the other hand, does, as do many
flowers. Again, in a
greenhouse, this shouldn't be a problem for you.
So, I think you should closely monitor the temps in your
greenhouse-see where you're at and where you need to be and then find a reasonable solution, probably no more than a heater for a few hours every day.
Good luck and let us know how you make out!