Hello, some time much earlier this year (I can't recall exactly when, but I'm thinking mid-early-summer-ish) I got ahold of some tamarind fruit pods.
After eating most of them, I got the bright idea of trying to sprout some of the seeds.
...
I tried the nail file method, the hot water soak method, and the hot water drop-in-fish-out method, and I either got a bad batch, or they'd been refrigerated, or I messed up, or something, because out of all 17-or-so seeds, I only managed to get two sprouts.
Now, they didn't come up immediately. I figured they'd all failed and rotted, so I tossed some into my pillbug enclosure and some into my veggie scraps, and *then* they sprouted.
.
I dug the one in the pillbug enclosure out and potted it, the other one I just dumped the whole handful it was attached to into a small plastic tote I had sitting around and covered it with potting soil and eggshells and let it sit outside.
...
Now it's winter, and I long since brought them in, but I don't know what to do with them.
I want to keep them alive, even if I never get anything from them besides a pitiful-looking little indoor potted tree.
They're tropicals, so I can't put them outside in the ground. This is upstate NY, they'll never survive.
.
I think I'd like to try making them into bonsai, since I almost certainly won't get any pods off of them.
.
...Any ideas? Advice? Does anyone this far north grow tamarind, even as bonsai?

Howdy Latifah, welcome to permies!

I had to go look up Tamarind as I had not heard of it. Sounds like a great tree to have!  Purdue U. Discription HERE.

In the article it says that, "Dr. Henry Nehrling reported that a tamarind tree in his garden at Gotha, Florida, though damaged by freezes, always sprouted out again from the roots."

It also says that " If kept (in pots) until the second rainy season, the plants must be cut back and the taproot trimmed."

So it might be very interesting to see if you can get it to bonsai!  Give it a try and keep us updated on what happens.

I have tropical plants that I put outside in the summer and bring in during the winter. Do you have a large window to set them in front of while they are inside?

I have a southern window in the living room, that's where they are right now.
it's not a bay window, but it's a respectable size (less than a foot from the ceiling, less than 3 feet from the floor, a bit over 3 feet wide)
the sun comes right in onto them, and it's the only window with something to set them on (we don't have proper sills)
I just don't want to accidentally kill them, they're so cute and our house is starved of green this time of year...
there's a cantalope sprout in with them, I haven't had the heart to yank it up, but it'll probably die after a few months.

they seem happy 😀

They look healthy...probably, being almost desert plants, they don't suffer the dry environment

I have some similar looking seedlings. They germinated from seeds picked out of of a block of tamarind. I had seen they were viable when one started to germinate with the boiling in my supper!
I have kept them fairly dry and they are in the polytunnel under a layer of hort fleece. We had -7C the other night and they seem ok still. Lightly scorched at tips perhaps. The leaves seem to fold up & close in when they are cooler.

That's very impressive that you could grow tamarind in cold weather like that. I live in Thailand where tamarind is common tree. It needs full sun and well drain soil. It is very big  tree and I have never heard the idea of growing bonsai  tamarind but you may try it, I want to see the result too. Anyway young tamarind leaves are edible. It tastes slightly sour and we use it in Thai soup.

I hope to see more of this project as you continue. Tamarind is one of my favorite "fruits," and the tree is beautiful. I'd geek out if I could hang out with one in WI. Plus little bitty tamarindo pods....that would be SO cute haha.

I'm surprised to hear Francesco say tamarind is almost a desert plant. I've only ever seen them in the humid tropics. What makes you say that it's a desert plant?

Pillbug enclosure?
You have peaked my interest.
Pillbugs as pets,pet food,composters,or what?

They are prone to fungal attack.  Even the big trees we have in Asia have lots of fungus in them.  So I would worry about wet soil and cold at the same time.  Soils avoiding a lot of composting stuff would be good.  No idea about bonsai, but would be careful and only root prune when growing outdoors under the sun and better air quality/flow

Indoors is a haven for pathogens.

Well, good news and bad news
Bad news, I only have one surviving tamarind seedling, the others that I had and that I've sprouted since have died of various causes. Against my better judgment I repotted my eldest and only surviving seedling into a ceramic pot and it's been living in the kitchen since. It didn't react well to the move (it's lost a lot of leaflets) and we had a spider mite scare a few weeks ago, but some neem oil appears to have cleared that up.

And pillbugs as composters mainly, pets secondly. I don't mind worms but my housemate had a rather traumatic experience with maggots so I'm not doing red wigglers for vermiculture.
Sadly I eventually had to get rid of them as well, but they were fun to keep while it lasted.

This is my survivor, pictured here with the spritz bottle and moisture tester for scale

i have a tamarind in toronto canada
i got it 4 or 5 years ago
it has gone through some rough times in the past
like in the fall the newest growth would be killed back by the cold
once it came inside this year it put on lots of new growth
not bearing fruit yet...
mine has a much more branched habit than youres although it was quite slow to start so i am sure youres will start branching soon
actually youres looks bigger than mine when mine was that age

I'm trying to figure out how to get him to branch
I think the mass leaflet loss might force the issue, every little bump in the stem is where a leaf was at some point. Several of them have little brown buds and I'm hoping at least a few swell up and start growing soon...

I would wait until summer to try and make it create branches.
They grow to around 100ft and don't like to make branches until they are much taller. But if you much do a quasi-bonsai. I would say that cutting out the center growing tip causes pretty much any fruiting tree to create one or more branches to become the new central leader/etc.