I have been leaving most of my seedlings outside even in the coldest nights (about 33F) and under a shade cloth. Many of them are still flushing due to the fact that they are fertilized with slow release fertilizer and our weather has been in the 70s most of the past month with just a few days with highs in the 50s and 60s. We have had 2 light frost, (but I still have live peppers).

I have been very surprised at how well they have done. No leaf drop (except for FD which has dropped all leaves), no morning wilt from the sun like I had last winter when root temps were below 60, even tender new growth is doing well. I do take the key limes into my unheated shop when night temps are predicted to go below 40, but have put them back out under the shade cloth when temps were only into the 40s with no sign of stress. They are all still in black plastic pots-- most in 1 gal pots but my 2 best key limes are in tall 4x4x14 pots.

What variety of plants do you have? How old are your seedlings? Are they under a shade cloth tent?

Your technique goes right along with what would be expected for citrus. How the seedling grow all depends on how dense the shade is. As I'm sure you already know, if the shade is to dark then the seedlings would be tall and spindly. However, it sounds like you have everything under control and are producing some nice quality seedlings. Thanks for the post.

Sunrise, I have lemons, tangerines, valencia oranges, clementine (not true), blood orange, FD, rooted trifoliate cuttings and one minneola tangelo (also not true) as well as the key limes. I have long piece of shade cloth draped from a privacy fence on the north to a table I use for potting on the south. There is another privacy fence to the east that blocks direct sun until it gets high enough that the shade cloth covers the low sun from the east. They are a little more exposed to direct sun form the west when it is low.

Millet, I think this supports you idea that it is the heat caused by the direct sun on the leaves that over heats the leaf causing abcission. With the shade cloth, at the worst, there are tiny spots of direct light that move fairly rapidly across the leaf. I have not measured soil temps, but I suspect the black pots are getting warmed some during the day helping to support growth, but not too hot.

It sounds like you have quite the mini orchard. What do plan to do with all the seedlings. Are you going to sell them or expand your orchard?

I will plant a few of them, but most will be given to friends and neighbors. I will definitly keep a couple key limes in containers, but I have given several of my key limes away already. If the quarentine is ever lifted, I will give them to my brothers and sisters in AL. Any forum members in FL are welcome to a key lime seedling for shipping cost as long as I have extras. I will need to make room for my satsuma seedlings before next winter.