Nice looking mimosa. If you don't have any experience with bonsai I suggest you do some research. Find yourself a good bonsai book or go online and read about bonsai care. There are several good sites to buy wire and plant food for your little tree, some will even have information on how to train your tree. There is actually quite a lot to know when it comes to keeping a bonsai alive and happy.
Dee

The owners are great and biggest in New England

Here is a link that might be useful: Bonsai

I purchased two books and took four from the library. Nothing gives the info I'm looking for. This tree is not hardy in my zone, yet it must go dormant. If I leave it outside it will die. I have tried growing them in the ground here and lost them.

I was looking for info on how to maintain this tree through winter. At that point, if it survives, I'll come back for help regarding pruning or repotting. It is in a very shallow tray.

Jane

Jane...I grew Mimosa in Pa with no problem but they were from native trees. Your gift was no doubt greenhouse grown and a true tropical so yes, it won't make it outdoors (neither will the slipware pot). I will suggest you get a shallow but much larger clay bulb pot and slip it into that. They like to be fairly evenly moist but not wet (similar to most tropicals) so a mix of 50% regular potting soil and 50% fine gravel/coarse Turface or Oil Dry will work for a potting mix. Don't feed it during the winter months. A humidity tray will help a little but, with standard heating of northern homes, will have to be pretty big.

Give it a home about 4-5' away from a south facing window with little or no direct sun during the coming months.

Bob

Jane...here's a pic of something to shoot for. The dog doesn't come with it.

Bob
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Thank you Bob. So I don't need to chill it down. I have it in a cold sunroom. I may have lost it because I left it outside and I think it dried out (forgot it). The leaves are all brown. I'll do as you say and see what happens in Spring. I thought it needed to be outside to go dormant.

Your tree is beautiful...as is your dog.

Jane

Yes, I would treat it like a tropical at this point. Unless it really got fried it will probably come back, give it a few weeks, you should see it budding.

Neither the tree or dog are mine, was at a gas station about 90 km from here.

Bob