SuperThrive's expensive and there's no clear consensus on whether or not it even does anything. I'd rather try something else. Trunks still green under the bark but it looks like it might be loosing some of the newer branches.

Acorn Springs didn't impress me, so I encourage you to contact them over and over till they respond. They are great when you want to purchase! I ordered an olive tree, and instantly many leaves got brown tips. Some were yellow and fell off. I tried to reach them by phone and email. No response at all! I didn't even suggest a return. I just wanted to know what to do. On Garden Web someone suggested to repot, fertilize immediately, and so I did that. Took the poor thing to a nursery here in town and she told me what olives like. Whew!! Finally no more new brown tips, many leaves staying green, but no new leaves yet. Good luck!!

Thanks for the responses guys. I mentioned I didn't think it was the water or fertilizing, but it certainly could be. Again, I'm a rookie and that was just my guess. Feel free to correct me - you all know much more than me so you're not going to hurt my feelings ;) My soil moisture test is pretty basic - I stick my finger in the soil about an inch down and if it feels completely dry I water it. I dump enough to submerge the rootball before it all soaks in. With this method I end up watering it every 2-3 days. Not very scientific I know but it seemed to be sufficient. The pot has some gravel in the bottom so drainage is pretty good. When I moved it outside we did get a couple pretty rainy nights so it probably did get a bunch of water those 2-3 days. Perhaps that is also a factor. I had assumed 2 or 3 overwaterings wouldn't be that bad given that it has pretty good drainage. I'm going to google the 'dowel method' now. Thanks for the tip. As for fertilizer I have to admit I only added it once at the end of the winter and it was some generic Miracle Grow plant fertilizer, nothing special for citrus trees. Go easy on me guys. I figured a generic fertilizer applied sparingly would either help or at worst no hurt too much. I'm going to order some citrus fertilizer soon. If the leaves are just falling off to make way for new ones I should see some newer, tiny leaves coming in right? It must seem like I have no idea what I'm doing... which is probably true it large part. I read some stuff when I got the tree and followed some simple rules. For a year the tree did so well I was convinced key lime trees were so robust you didn't have to do much at all. Clearly I was wrong.

Again, check the soil way down at the bottom, Mile High. You made up your own mixture, and believe it or not, it may still be retaining too much water at the bottom of your pot. Cactus mix and perlite will still retain too much water. Especially when you bring your tree inside for the winter. Which is why Mike shared with you using the 511 mix. O don't even use cactus mix and perlite in S. California, where it is almost as dry as Colorado, and I can keep my trees outside all year. My customized 511 mix is 3 parts bagged mix (usually MiracleGro Vegetable Soil), 1 part perlite and 1 part small bark chips (usually reptile mix or coarse orchid mix). I think the issue you're having is from past and possibly continued root damage, some of it a delayed response, and possibly some of it a response to continued root damage. I think the roots are damaged enough that the plant cannot sustain growth at the apical ends of the branches, and they are just dying back (called Die Back, interestingly enough). So, I would make absolutely sure you're not continuing with more root rot. I think the chlorosis you're seeing being caused by inadequate root growth, not inadequate fertilizer. If the roots are so damaged that they cannot take up nutrients, you'll see chlorosis, despite fertilizing. Your best bet? Re-pot now, with 511 mix. Trim off any dead, rotten roots. You may even have to flush the pot with a weak bleach solution to stop the root rot (I think Mike has had to do this in the past, so search the forum for the bleach to water ratio, you don't want it to be too strong, or you'll kill your plant). Then, once re-planted with a properly porous mix, start fertilizing with 1/2 strength Foliage Pro until you start to see some recovery. Once you do, you can move up to full strength Foliage Pro, and add some Osmocote Plus time release fertilizer (please do not use anything else, many of the time release fertilizers have too much urea--based nitrogen, which will burn the roots, and also do not contain micronutrients, as Osmocote Plus does). Patty S.