I think you are correct about the shock it is going through.

I would not prune. I suspect that your tree will be fine. Give it some time and as much light as you can.

I can't tell frtom you r photos if leaves are light green, indicating nitrogen deficiency, BUT I would hold of doing anythin about that until it is better established. In other words hole off on fertilizing - it may do more damage than good.

it is stressed ... destress it before you come up with any other plans ..

water it properly.. provide proper light .. and just give it time..

fert is not a response to stress ...

i dont understand what filter you used on the camera ... is the wall yellow also??

its has transportation stress from grower to seller to you.. falling out of the pot stress... which we may as well call repotting stress ... and your house isnt the greenhouse it grew up in ...

just let it de stress ...

i see the rack.. how far away is the light .. are those blinds ever get open ... how cold will that window get in winter ... do you have forced air furnace [possible humidity issues] ...

you have plenty of time to figure that all out ... just dont try to fix everything in the next few days...

5 bucks is a great price for this.. and no matter what happens.. even abject failure.. you will learn something.. and that is a pretty cheap lesson ... just dont love it to death trying to do it all too fast ...

ken

ps: growing trees in the house is not easy ... but one key is.. water it like a tree.. not like a water loving houseplant ....

I have had citrus recuperate from 100% foliage drop, they are prone to lots of issues and seemingly impossible to kill at the same time. Citrus tend to grow in pronounced spurts and states of apparent dormancy, let the plant tell you when it's ready to move on. In the meantime, go very easy on water, err on the side of too little than too much, try to provide as much light as possible, and do not fertilize it. I would not expect too much till Spring. Once you eventually see signs of new growth, you can increase watering and start feeding. Get it outside in the sun in the warmer months if that's possible. Limes are my favorite as containerized trees, mine always have just about the most fruit of any other citrus.

Get it outside in the sun in the warmer months if that's possible.

==>>> with ANY houseplant.. you have to harden it off to direct sun ... NEVER take it outside into direct sun ... or you will sunburn the leaves.. and if bad enough.. they will all fall off ...

a week in full shade.. then a few hours of sun at dusk or dawn.. and then eventually.. out into sun ..

but dont forget.. your watering schedule may need to change.. if you put a black pot in sun ... it depends on the size of the pot.. and how fast the medium heats up ... and you can avoid some of that.. if you hide the pot itself from sun .. just set it behind something so the pot itself doesnt heat up ...

otherwise.. margarita basically explained how to water it like a tree.. as i vaguely stated above ...

ken

The yellow light is my LED grow light to supplement the little amount of direct sunlight we get from that window. Thank you for the input everyone!

One hears from time to time "not to fertilize when a plant is having a difficulty" I have never seen this advice in any professional literature. Reading about citrus trees affected by HLB the advice is to feed the tree with both soil and foliate applications.

Silica, the larger contest is that we are talking about a stressed tree, growing in low light (for Citrus), containerized, indoors, at the cusp of October, in Canada. Fertilizer is not magic for a tree that is marginally staying alive. Having said that, I think I will go out into the glorious sunshine and fertilize my potted Citrus collection.

I would agree with most of what was said here, definitely on watering like a tree. Make sure that you give it enough water that it runs freely out of the drainage holes, then leave it until it is on the dryer side. Depending on the humidity in your house I would definitely put it above some big rocks in an oversized drainage tray to raise the humidity around the tree a bit, since you're headed into winter and will need to use heat which can dry the air. Don't be surprised if a lot of leaves fall, usually a tree can recover from that. Just leave it be and give it time. Trees take awhile to recover.

On fertilizer, I wouldn't give it an application of fertilizer, but some slow release fertilizer in the soil mix might help a bit. Beyond that I wouldn't give too much fertilizer to a stressed tree.

I don't know what kind of pot you're using, but keep an eye on moisture if it's plastic.

wow, that is a cool setup!

Nice job in Canada from a amateur citrus grower in south florida.

L.L.O.Z.6a; I bet that tree thinks it died and went to Heaven.

Steve