Assuming the tree has been conditioned for full sun exposure (such as after spending the winter indoors as a houseplant) I would go with full sun followed by part sun as opposed to part sun all day.

Why?

More sun = more energy for the plant. Citrus- assuming they have been conditioned for it, can handle full, all day sun.

Thanks justaguy for your input. I figured any amount of full sun was for the best, but as a citrus newbie I thought I'd throw my question out there to you experts.

To clarify my original post, my ponderosa lemon tree that gets only partial sun, but gets it all day long, has more total sun exposure than the key lime that gets a few hours of full sun with a lesser amount of partial sun the rest of the day. I guess it's a question of quality (full) sun vs. quantity (all day but partial) sun. Both trees seem to be thriving in their respective spots, so I guess I shouldn't be concerned. They get plenty of heat and humidity, but my backyard does tend toward the shady side.

Thanks!

ah, I didn't realize those were the 2 choices. I thought both trees got sun for the same amount of time, but that in one place part of the time was full sun.

I have no idea which would be better in this case. Still, they can grow as houseplants so I wouldn't worry too much about it.

BTW, I am most certainly *not* a citrus expert ;)

Something to make you ponder...

I have a lime tree that gets dabbled sun all day under a tree, and it seems to have greener leaves and hold its fruit alot better than it did when it was in full sun all day. It use to be yellower, flowers smaller,which dried up and fell off fast, and I would loose fruit.

But my grapefruit, oro blanco in particular, thrives only in full sun ALL day! LOTS of HUGE flowers and huge fruit.

My ponderosas, the ones in the dabbled sun are keeping their HUGE flowers and greener in appearance, as compared to the ones that are in full sun all day. Those losse their flowers qickly, but the fruit get huge! By the way, those leaves of the full sun one are not as green as the ones in the part sun..

My lemon meyers, they only grow fast and very robust in FULL sun..

Guess it depends on the variety of citrus...Weird ha?

Here is something that will even probably answer your question even better..
I have had 3 sunny days in the past 3 weeks..Yes, count them, only three!
It has been raining, drizzling, and been stuck in the 60's a majority of this month, and yet my citrus are NOW as green as can be, and healthy..It is 58 today...July 19 and drizzling..
They are loaded with buds and fruit. NO sun!
Just a few weeks ago, I was complaining they were yellowish, and even a lighter green than when I bought them when the sun was out everyday and they were all in FULL sun... Now I have no complaints...lol

One of my ponderosa trees was blocked by sun from a rasberry bush that grew about 5 feet tall, loaded with big flowers and very green. A couple of days after sticking it in full sun, the flowers dried up and it turned a lighter green..NOW it is a darker green and loaded with big flowers again with all the clouds and rain..

Now, my grapefruit, that one has a mind of its own. It is most green in full sun and in all this crappy cloudy rainy weather, and in winter under lights..lol

I thought I was the only one strange at times, so are my plants!!
Here is the kicker, I havn't fed them for about 3 weeks now, and they are as green and as flowery as can be..lol!!

Mike..:-)