Woody plants often die from the top down, but I fail to see the cause for this particular problem with the information given. I'll typically look to the root system, however, on both containerized plants and those planted in situ. Lots and lots of things can go wrong down there with the soil system, the root system, and the soil/root system. Die back is one of the first signs of soil compaction, poor oxygen content, flooding, root damage, etc. in soil planted trees, by the way. I'm not saying that your tree hasn't suffered from cold damage, but that it could be almost anything. We just haven't heard enough information. Hey, it could even be that the tree came to you with dead tissue, and it's just taken this long for it to turn black. The reptile bark is a good option for the bark fines so often talked about on this forum and others. Usually made from fir, I believe, and a good size for this purpose. Bagged potting mixes almost always need to be amended with something to make them decent (ALMOST) and that bark is a good choice. By the, just do you know...the sealing of any woody plant after pruning is not recommended on large or small shrubs or trees.. Such a practice can actually impede the natural 'healing' going on within the tissues. It was thought at one time that gunk needed to be applied to a pruning cut in order to prevent the tree from leaking all over the place (ha) and also to prevent disease organisms from entering the tree. We apply dressings to people, not trees. We leak when we are cut and our wounds need to be covered with something in order to keep the good stuff in and the bad stuff out. Trees simply don't work that way...and it's a good thing. Best to know where to make a proper cut and to allow it to heal in a natural manner. We know better now. There ARE exceptions, but they are unusual and specific. And don't EVER expect good advice from the folks at Home Depot or Lowes'. ;-( (Here's an old bad saying: "I wanted to be a tree surgeon but I couldn't stand the sight of sap.") P.S. I'll bet that if you return to the Home Depot in spring that you can find some nice looking Meyer Lemon trees there. Just in case you want to add to your collection.

Your tree looks great; so don't stress. Whatever did that damage to a few leaves is not there now. BTW 12-4-8 is the perfect NPK ratio for Meyers; just be sure it has, or you add Mg, Ca, Iron, and Zinc. Your tree shows no evidence of any of those deficiencies.

Thanks! Was getting semi worried and didn't know what I was doing wrong. Moved my trees to a spot that gets a little less sun, hopefully this fixes the problem.

So there are any holes in your ceramic pot?! The plastic pot is inside the ceramic pot? If so, this is your mistake. The surplus water from every watering will stagnate in the ceramic vase and the roots will develop root rot in no time. Aeration of the soil is also inexistent in this arrangement, so root rot in no time again. To save the tree: remove it's fruits, remove the roots from the current soil, cut away rooted roots, re-plant-it in some soil with at least 50% perlite or other aerated stones, and keep-it on top of the heater so that the soil temperature to be 23-28 degree Celsius. The pot that you will use needs to be smaller than the current one, with many aditional holes on the bottom, each at least 5mm in diameter! Use the ceramic pot for anything else ! Or dispose-it!