When anyone asks me what's the best time to prune a mimosa, my instinctive response is, "Any time you can find a chainsaw."
That's very judgmental of me, I know, but heck, that's pretty much my job. And mimosa is one of those plants you either love or you hate. I hate it now. But I used to love it.
Why, when I was a kid, at the nadir of sensibility and good taste, I thought mimosa (Albizia julibrissin) was the prettiest tree in the world. Its leaves were like ferns. Its flowers were pink puffballs. And it bloomed in summer, when few other trees did.
A Miracle -- My Wife Agrees!
Judy, who notices very few plants, has fond childhood memories of mimosa too. She remembers climbing up in her neighbors trees to smell the flowers. I think they smell faintly of gardenias -- not like my son's socks, which would actually cause you to faint.
How It all Began
Native to the Middle East and Asia, mimosa was brought to this country in 1785 by the famous French botanist Andre Michaux, who planted it in his botanic garden in Charleston, South Carolina. It grew quickly into a vase-shaped, flat-topped tree, 30 to 40 feet tall, and it loved the Southern climate. The flowers, attractive to butterflies, hummingbirds, and colonial gardeners, ranged in color from nearly red to deep pink to flesh-pink to white. On one road-side near my home, there is a row of them, each a different color. Here's the usual pink.
And here's a white one. I really like the white, but I've never seen it for sale. The various colors are due to genetic variation, with pink being dominant. Where I live in Alabama, the trees usually start blooming in June and continue for several weeks into July.
So Why Do I Hate Mimosa Now?
Two reasons, First, like most all fast-growing trees, mimosa is notoriously short-lived, subject to many pests, and will die on you in a heartbeat. When people ask me the best way to get rid of a mimosa, I tell them to make it the focal point of their landscape and it will be gone momentarily.
Second, after the flowers fade, the tree grows hundreds of 6-inch long, bean-like, brown seedpods which hang from every branch. The seedpods persist all winter, even after the tree has dropped its leaves. Few trees look as ugly or more forlorn.
But wait! It gets worse! Each of those pods is filled with seeds and each and every one of them germinates somewhere, even in cracks in the pavement. Plant one mimosa in the yard and soon every house in the neighborhood has two or three mimosas. coming up in the fence, the middle of a bush, or by the silver propane tank.
Mimosa adapts to almost any well-drained soil, laughs at heat and drought, and does not mind if you spray-paint the trunk white, hang tires from the branches, or park your pickup on top of its roots. In hort class, we called it a "pioneer species," because if you disturb the land, remove native vegetation, and open the tree canopy to light, it's one of the first trees to appear. That's why you see it growing along just about every highway and country road in the South. Northerners be glad it doesn't like your cold winters, but with global warming, who knows how much longer you'll be free?
Not Fooling Me
Recently, a new kind of mimosa was introduced to the gardening world, a purplish-bronze leaf selection called 'Summer Chocolate.' The hype over its undeniably pretty foliage and pink flowers was overwhelming. Probably many of you bought one and are enjoying it right now. But not me.
See, any mimosa that flowers is going to produce seeds and lots of them. And if a thousand seedlings come up in my yard, I don't care if they have green leaves or purple leaves. They need to be eliminated with extreme prejudice.
So my advice about when to prune a mimosa remains the same -- whenever you can find a chainsaw.
