Mimosa is a common name that refers to multiple species and even different genera of plants. Which one are you working with?

I have some mimosa seeds that I would be glad to share with you. It will take longer to get a tree like you may want but this would work a lot better. Are you wanting what it called a silk tree? Drop me an email with your address. Hope you have good luck.

i am pulling the things up and killing them (seedlings) - where are you located? Maybe I could send you some seedlings?

Pat

You have a couple of more options on rooting mimosa cuttings.
Try airlayering, just wound the limb and put some peat moss or good Potting soil in aluminum foil and put it on the limb.
Keep it moist. It should root in about 6 to 10 weeks.
Another way is to build a humidity chamber.
Go to walmart and buy a cheap clear storage container.
Put the lid on the ground and place a flat with course sand on the lid.
Place your cuttings in the sand.
Place the tub part over the cuttings upside down and it will hold the moisture and will heat up.
Just keep the sand moist about once a day and you'll soon have roots.

Do you put any air holes in the humidity chamber?