Last fall when I brought my plants in the greenhouse for the winter, a couple of my trees were coming into bloom. These are trees planted from store bought orange seeds. I was excited to say the least. Of all the blossems, only one orange remained on each tree. They're only about the size of a nickel and they're already turning yellow. Why are they so small? I'm wondering when I should pick them. Does this mean they are getting ripe, or will they continue growing?

The color change from green to ripe occurs pretty much at full size, so your fruit seem to be too small yet for this to be happening. With first fruit, you may get a small version in the first year or so on seedlings, which also may produce atypical fruit as a one off, then go back to growing taller and not fruit again for a while. If your small fruit is turning yellow way too early, it is probably going to be shed, so you will find it on the ground.

Thanks for the reply. I guess I'll pick them before they fall. I'm courious to find out how sweet (or maybe how bitter) they are, I'm woundering if the pot size would have anything to do with the fruit size? They should have been re-potted to a larger containor last year, but I never got around to doing it. So they're a large potbound plant in a small pot for now.