mimosas take transplanting not at all well, so if it's taller than you are, I'd have second thoughts, and hope for a seedling...which is about all I honestly know about mimosa, since they're naturalized here, and I'd rather have one in the neighbor's yard than mine- they're not as messy as the golden/honey acacias, but they do drop their share of litter.

but dig the hole where you want to put it, cutting the sod and putting it aside to hide your deed later. the hole should ideally be half as large as the spead of the branches, no smaller than a yard across, and 2 feet deep, 18" is better.

soak the hole with water.

then- ideally right after a good soaking rain, lay out a tarp near the tree, and dig it up, staying at least 2 feet away from the trunk on all sides. may need a lever to pry it loose. get the root ball on the tarp, and drag it over to your yard. it will want to be planted to the same depth, so adjust the soil level in the hole as needed (since you're digging down below 'garden' level' adding a few shovels of compost to the pile of dirt is a good idea)

backfill to just below surface level, water it well to settle the dirt, backfill some more, water...then walk away for an hour or so and let things rest before you finish, mounding the dirt into a donut around the truck (helps direct water to the new planting) and then mulching the whole shebang.

any left over dirt goes on the tarp, gets dragged to the neighbor's yard to backfill the hole, which gets watered and leveled, and the sod laid over it.

Don't plant the mimosa near your house or near any water source. My dad was a plumber and he used to gripe about mimosa roots getting into people's pipes! They are very invasive and will cause you hundreds of dollars (and a dug-up yard) in plumbing repair. This is the only tree my dad ever mentioned ... and he mentioned it ALOT!

We dug up one and found one root went from one side of our house all the way to the other. It had followed along the basement wall and a new tree came up on the other side. They are pretty, but I hate them. Still have not managed to kill this root and don't know how many other may be out there...

thanks for that plumbing information. My son pulled one up and it survived - after two years it is about a foot tall. I made a large planter and of course made his prize the focal point. I shall pull up today! It is only 10 feet from the hose bib.

Yikes!