Young Kieffer (makrut) lime - cry for help
Sorry for this very long post... I am a neophyte, so I'm not entirely sure what information is important. I'm hoping that someone can help prevent me from killing off my adorable sapling with my cluelessness.
Last year I bought three tiny Kieffer lime trees - no branching, just the main trunk about 10 inches tall and a dozen or so leaves each. I've been keeping them indoors mainly because of their size (they're so small and fragile looking!). They are grafted onto what I believe to be some type of trifoliate orange. (It's been a while since one of them grew a rootstock sucker, but it had trifoliate leaves - and I think flexible thorns as well.)
All three have gotten the same care, or lack thereof. I've made pretty much every mistake that there is, yet somehow they are still hanging in there.
They live on a windowsill. For the last three months I've given each about a half-teaspoon of Espoma every 4-6 weeks. (They're very small.) Recently I sprayed all three with chelated iron, in two applications about a week apart. I usually catch and pinch suckers before they can grow longer than an inch or two. My watering is very inconsistent, but I always check all three at the same time (and water each if it needs it). All three have the same pest problems - spider mites which seemingly materialized out of nowhere, and scale which they acquired when I very unwisely brought home a new potted lemon to keep them company.
Two of the three developed new branches and are growing, looking pretty dark green, etc. They have very large leaves - I think the size is probably due to not getting enough sunlight - but otherwise seem healthy aside from the pests. Both put out a couple of tiny flowers a few months ago, but otherwise they haven't shown signs of stress that I can see.
The third, however, is in really bad shape. It only added one very small branch, and began to lose leaves about a month ago. I opted to move it outdoors so it could get more sunlight, despite the risk of shocking the poor thing with the sudden change.
Unfortunately, it's gotten a *lot* worse since then. At this point it's lost most of its leaves, and the remaining ones are very pale green in color. Sunscald, overfertilization, underfertilization, overwatering, under watering, disease, micronutrient deficiency, slugs, or did the relocation just weaken it enough for the pests to start finishing it off? Do I risk traumatizing the poor thing even more if I pull it out of the pot to check for root rot? Is there a way I can treat the pest problems without using any chemicals that will further stress it? Is it allergic to the cottonwood which keeps shedding on it on a daily basis? (Okay, I'm pretty sure that's not it...)
P.S.: Thank you to all of the brilliant citrus lovers here - even though this is my first post, I have already learned a lot by reading your responses to others. Unfortunately, I was starting from zero, so in absolute terms I still don't know that much. ;-)
Here is a picture. It's not normally perched on that pile of junk - I took this at night so I had to move it into the potting shed, er, porch light area.