I have been growing mimosa for around 18 months in soil, the seeds are easy to germinate and grow quickly if the soil is kept moist during seedling stage, the first plant, is becoming quite large, i tried to clone a few cuttings and was unsuccessful, i gathered that it would be much easier to start with seed to avoid any further damaging to the plants, right now i have 20 mimosa, 10 confusa, 6 acuminator and 3 types of viridis, cloning viridis is very simple, the leaves can be used to sprout new clones...
so try to avoid attempting to clone mimosa, it is quite difficult unless you have the right setup and know how, best to get a stack of seeds to start with and harvest the seeds from the trees in the future to keep the ball rolling.