What John said..Then too I think you have spider mites from that poor tree not being at it's robust state..I would wash all the leaves off under a hose or shower head and spray right away..That is mite damage to me...It seems your very new growth is being attacked first since the leaves are cupping and curling. Is it possible you are under watering too since that mix looks very dry.?

Thank you both for the help and input. Much appreciated.

Re: roots I will move it away from the window and get a heating mat.

Re: mites. I don't see any webbing or mites on it anywhere. I know they're very hard to see but considering there are almost no leaves left, think you'd be able to see a few mites or at least the webs, right? I have struggled with gnats (since moving it indoors) on top of the soil..I've read and that the larvae can kill the tree. I've tried a few things, but nothing seems to get rid of them for good.

Re: Water, the moisture meter says the at the (root level) moist, closer to the wet side likely because I just watered yesterday. Do you think it needs more? The soil is only dry about an inch down. I will add a little vinegar as suggested.

No. You will not always be able to see all mites unless you use a magnifying glass and look very closely under the leaves..Many will not even spin webs until every last leaf has been eaten then they just move on...I'll bet you have mites..

Putting heat under you pots and moving away from the window will kill your tree. What John was saying is that if you plan on keeping your tree in that window, warmer roots would be very helpful because it can get very cold in a window..)

How do you water? Do you use a bucket, sprayer, glass of water? How deeply? How much? How often? Do you use fertilizer?

Okay, gotcha on the mites and the heat!

I water with a pitcher, about 1/2 gallon, every 3 days. I thought it was going rather deep, at least according to the soil meter, but water has never run out the bottom.

I haven't used a fertilizer, Thought I wasn't suppose to do that until spring.

Thanks again!!

I would try watering more deeply, less often. Perhaps water a gallon or more every 5+ days. That way the soil is more evenly moist and it flushes more oxygen into the soil and roots. I wait pretty long between watering like 2-3 weeks but my trees are in a 45-55 degree garage so they are fairly slow growing. As long as you check a few inches in the soil and wait until its dry before the next watering you'll be fine. I would also spray it with Neem oil once a week for 2-3 weeks and that should help with the mites. Its pretty much a guarantee that you'll get them when growing indoors.

Yes, water deeply and then you should take your pots to the sink or on a first warm day and flush your mix out since you are probably getting root damage due to salts the due to the way you water and the mix you are using..Spray for pests whether you think you have mites or not just in case..

Thanks very much for all the input/recommendations. Hopefully it will turn things around for my tree :)

For mites, you can check this way: mist the leaves. Then wipe them with a paper towel, top and bottom. If there are mites, you will see yellow (or other color) smudges on the towel.

3 days between watering does seem too soon.