The only difference,

Actually there are several other possible differences. :) THe color differences would indicate a nutrient difference for one.

But the primary one is seed genetics. Not all seeds of the same variety have exactly the same DNA and embryo size is one of them. It is one reason why many selectively plant only the largest seeds out of a packet.

But surprisingly, like the runt in any litter, most plants will quickly catch up with with the big guy once transplanted to the garden assuming optimal growing conditions.

Years of research in greenhouse gardening just don't support the claims made by most so-called "plant light" manufacturers with the exception that they can make a difference in blooming times - something we aren't usually interested in rushing with garden plants.

Dave

I actually have 5 of each (5 in the cool/warm light, 5 in the cool only light.) Maybe the nutrient deficiency can be attributed to the light assuming they are using the light for photosynthesis. Anyway, I went out and found some more of the aquarium/plant bulbs so hopefully they will catch up soon!

The one on the left was under one(1) light and the one on the right was under two(2)lights?

The one on the left, along with 4 others that look just like it, were under 2 - 4' long cool fluorescent tubes. The one on the right, along with 4 others that look just like it were under 2 - 4' long fluorescent tubes, but one was a cool light tube and the other was a warm light (aquarium/plant type light bulb.) So I believe the reason the one on the left is so scrawny is because it was only under the cool lights. I now have it under the same lights as the one on the right and hoping it catches up quickly. :)