Mimosas don't make a full tree. I don't think pruning will do anything except give you a misshapened tree. However, I have been known to be wrong on a lot of things.

Personally, I think that the light airy look to the mimosa is one of it's beauties. I have never seen one that could be considered "full"

another thing to consider is that the mimosa is known to be easily attached by fungus, etc. Perhaps cutting the limb, leaving an open wound, would not be the best thing to do.

Have patience. It's a very young tree. Give it time to do what Nature meant for it to do. You may be pleasantly surprised.
PB

Diane, Mimosa sort of do their own thing...I'd just let it continue to thicken trunkwise and it will eventually branch out and make a broad spread on the top. We had one which we cut to the ground several years in a row because it was too close to house...every year it would resprout bigger-trunked and taller than ever. My husband would leave it (at my insistence) until it touched house or roof. Finally it shot up way above eaves and we left it to shade that corner of house.

On the other hand, others we cut down woud just make a 3 foot high multibranched shrub every year after that. I left them bcause they looked like huge ferns but of course never bloomed. I don't think you could predict which route yours would take...a new strong main trunk or just shrubby growth.

As to seeding, for thirty years we didn't have many Mimosa seedlings in our mostly shady garden, then we cleared out a few large old (dangerously close to house) Pines and the next year we had dozens. But no more seedlings from Mimosa than from Pines, Sweetgum, Oaks, etc. plus luckily a few Magnolia and Dogwood. Dealing with seedlings is just a fact of gardening and thankfully we get some sweet along with the bitter. josh

the nursery man (private owned nursery) had been in business for years, and he told us to keep it pruned or it would get leggy. So each year we would prune the limbs back to keep it a med size umbrella.It bloomed well after about four years. BUT last year it died, at 10 years old. (We had noticed that year the squirrels had done a lot of chewing on all the limbs.) There are branches coming up from the root, so guess we will leave it for the fern effect also. Will it not grow and be a blooming tree again from these new shoots?????

WannaBeGardener, We contine to cut the shrubby "ferns" back very year, but if you dont, yours will probably continue to grow and make a multitrunked tree. But it might be fairly weak..they are very softwooded trees. I'd just leave it if you like it and see how it goes. Unless you need a long-lived tree in that space or want a more normal looking tree...lol. I had space to sort of play around...plus I had plenty of trees and didn't have to depend on the Mimosa to have a bit of shade. Just depends...as I said earlier, you can't really predict, so if a nice small tree is needed, maybe a Dogwood or Amelanchier would be better in the long run. (Have I see-sawed back & forth enough on this yet? lol). Just trying to help but I've probably confused everybody by now. josh

Guess we will leave it and see how things go. Have lots of room, and plenty of trees around so no problem there. Will let you know how it turns out. I see lots of them in the wild with multi trunks. Guess thats what happens when the main stem dies.

First of all, let me say thanks to WannaBGardener, Josh, Amyta, and PeaBee4 for all your suggestions and stories of "your" mimosa trees and ferns (that's an interesting one).

Taking all you have said into consideration, I'm pretty sure I'm going to lop off her top. Last week I said 7'... this week I can easily add another 3-4" to her trunk. Trust me, she's not a pretty sight. She looks good to about the 3' height and that's where I'll cut her off. By doing so, I'm thinking that she'll fill out from below. I do want a canaopy type look and I just can't see it happening without a nip & tuck.

I know many people have thoughts of these beautiful trees being a nuisance, dropping seeds here and there. I'm sure it won't be a problem for any of my neighbors who happen to get lucky :-) I live in a brand new tree-less subdivision and we're all doing our best to change that.

I'm only saddened that they have a short life span (15-20 years is what I've read) but actually and I only get half of that, I'll be happy.

Without cutting off about 4' of the single thin trunk, I just don't see my mimosa creating a full or canopy look in a few years.

If any of you are interested in seeing a picture of what she looks like now, you can email me at dianewarneke@yahoo.com and I'll happily email you a photo.

Again, thank you all. Oh, BTW, I'm formerly a Michigan Gardener and have found that SW Kentucky gardening in clay, heat and humidity is a whole new ballgame -- and I'm enjoying each inning.

Diana, Good luck to you and "MIMI". If and when she blooms you can send photos to your Michigan friends...they'll be green with envy. I think Mimosa is one of the most tropical looking things we can grow...and they attract Hummingbirds...how cool is that? josh

Jo, even if Mimi never blooms, she'll still be a great tropical tree tease to those back in MI. Yes, it is one of the most tropical, by far, yet another tropical that comes to mind is magnolia! Maybe that'll be my next project :-)

Mimosas are short lived trees anyway. Pruning is supposed to keep them alive for about 20 years, but they eventually die. Most unpruned ones die sooner than that.

I have just been reading your posts on Mimosa trees. We bought a farm property 2 years ago in Azle, TX and my favorite thing about the property was the gigantic Mimosa canopied tree in the backyard. Never seen anything like it. It is a cluster of 5 trunks each approximately 20" in diameter. The seller told me he had never pruned it but just made sure it had lots of water. He estimated that it was over 13 years old when I purchased the house. To my dismay this Spring the tree has no leaves and appears to have died. I have been beating myself up thinking I did something to it but from what I am reading this tree is fragile and life expectancy is 15-20 years?
If anyone wants to see it email me, it was gorgeous and the hummingbirds are saddened as am I. janet

We have many large old mimosas in my neighborhood here on the south coast of Massachusetts. But some of them died during the summer last year, after leafing out. I think it was the fungus. The smaller, younger specimens in the area were not affected. You could always plant a new one. They are rapid growers, even in the much cooler climate here. I imagine they grow super fast in Texas!

How do we prune Mimosa's to make an umbrella shape?

I dug up two Mimosa trees to plant in my yard. One I planted at the back of my house near my lower patio and upper deck and the other one I planted on my second level of yard from another view from the upper deck.
The one near the house is also about 20 feet from my septic and I am now wondering if this tree will become a problem. In three years it has grown up above the rails on the upper deck. It has an amazing umbrella shape. I trimmed if back once and plan on doing it again after this season is over. The second one has grown much slower and I had two lanky limbs that grew from the ground so I twisted them together and then I had one straight tall trunk. It has been intertwined for over two years now and it is so beautiful. They both are full of blooms and the hummingbirds, butterflies and many other small birds have been enjoying my trees. I am sitting outside as I type this and the hummingbirds are buzzing all around me.
I love Mimosa trees...makes me feel like I am on the movie Avitar....:)

We planted a Mimosa in our front yard which is south facing in December of 2013 and it grew like crazy that summer. Very Jurassic park like. It was multi trunked when we bought it but now we are concerned that it will not grow tall enough and spread and be too close to our house. Should we be tying to with something to encourage it to grow up and not so much out? I appreciate all your help and comments and have learned a lot reading the posts. This would be a tree that would give us a major help in shading our house in summer in zone 8 in Arizona.

We have cut one back, dug it up, multiple times for 30 years! sure wish I had one of those only live 10 or 15 years. It was growing on a bank and we noticed the wall was bending out. When we took the wall down to replaced it, it was the mimosa roots that was making it bow! Scariest was when my husband was putting in a french drain and we found one root bigger around than my arm that had grown along the side of the house and a new tree was coming up about ten feet the other side of the house. finally killed the second one and drilled holes in the root and poured Round up in them, but the original one is still there. luckily it is the only one...I hope.