Could be any number of factors. Do you have any pictures? Those would help us out. I personally find that a flush will abort when conditions are too hot, either the ambient temp is much higher than the tree's accustomed to or the pot itself overheats.

In any case, be more concerned with the overall health of the tree. For example my last flush blackened up and died off but the rest of the foliage is dark green and not dropping any of its leaves. I took it as an indicator that the tree just wasn't ready to take on more growth. Not a big deal at all.

I agree with baconquest. The plants likely got too dry. Checking the soil in the pot with a wooden skewer should get you an accurate read.

This was a spring of aborted flush for me here northern California. We had a dry Jan/Feb and then a heat wave hit. That combination along with (draining) mole tunnels and an irrigation failure had multiple trees abort their flush when they did not get water for weeks.

Citrus need plenty of water during their growth spurt / flush.

good luck!

Thank you for those responses. I am pretty good about monitoring the soil moisture now. I have a meter but also use the good ol' fashioned finger in soil method, as well. Perhaps it was just that the trees could only sustain but so many new leaves and it was simply aborting some new leaves to focus more energy on the leaves it chose to continue growing. The "hot pot" theory also seems reasonable. With such a small volume, they probably do get pretty warm during the day. I will try to attach a pic. I knew someone would ask :)

Edited to add pic: This is the lime that was very stressed and shed all leaves before flushing several weeks ago, especially on the branches that get more sun. This branch (and a few others) didn't do as well.

This post was edited by Grove_Digger on Tue, Jul 30, 13 at 18:50

That picture will be helpful. That flush aborted before it even got a chance to get going! :-(

I have only seen this on my plants when too dry and hot. But, there are a number of things that could have happened. I suppose it is possible it got too wet. In any case i am suggesting that the roots did not like the growing conditions.

Another thing that you might check is the soil and water pH. Also, you mentioned that the pots are in some rather hot sun; did the roots get too hot?

Your others are doing ok, but i still have to ask: Are you watering with water that is off of a water softener? (no no - salty).

I trust that some of the other forum members will chime in and assist.

One of the major issues with container citrus is when the pot (roots) get too warm or cold in relation to the temperature of the plant. Too warm roots (black plastic pot in full sun sitting on concrete) and a cooler plant leads to root rot. Too warm plant with too cool roots (full sun window indoors) leads to new flushes dying. Remember with citrus, first the roots grow (and citrus roots do not like to grow into cool soil); then the leaves and branches grow.

Thanks for the questions. No water softener.
The pots would get less sun than the plants. We are on the 3rd floor so when I said patio, I should have said balcony. We have wood railings that screens the bottom portion of the trees and the pots. Sun does "peek through the railings and could warm the pots, too. Or there is just a discrepancy in the temp of the pots and the trees....had not thought of that prior.
My most recent tree is the blood orange. I mix its soil with wood shaving that came for Four Winds nursery. It drains the best and seems to be the healthiest. I have consider changing the soil with the sweet lemon and the lime to see if better draining soil would do the trick.
Here is a pick of a few of the trees. Little Washington Navel on the left, blood orange in middle and Meyer Lemon on the right. Far right is the sad lime, as you can tell. Fortunately, there is a bit more foliage higher up.
This is just so you can see the pots and the balcony railing. They are all up on roller, so get some air from below and are not in direct contact with the concrete (note: i was moving things around and the blood orange is directly on the ground in the pic) Top of the railing is just at the top of the pick. Again, south facing but covered. So I added grow lights, as you can see, a few weeks ago to supplement. They seem to like that, though the Meyer Lemon has yet to flush.
And maybe my fear of root rot caused me to be to cautious with watering this year, though they seem to hold some moisture over the course of a week.