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 hey, 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.
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. Thriving in the southern climate, the plant grew quickly into a vase-shaped, flat-topped tree that reached 30- to 40-feet tall. 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 roadside near my home, there is a row of them, each a different color. 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.
There are two reasons why I think mimosas are a tree you should never buy. 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.
Each of those pods is filled with seeds 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 anything you do to it. In horticulture 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.
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 are going to produce seeds and lots of them. And if a thousand seedlings come up in my yard, I don't care what they look like, they need to be eliminated.
So, my advice about when to prune a mimosa remains the same—whenever you can find a chainsaw.
The pink "powder puffs" of mimosa flowers appear in early June throughout the South. Fernlike leaves give the tree a lacy, graceful appearance.
A common problem with these trees is mimosa webworms. Silken webs wrap clusters of leaves together, and the caterpillars inside those webs eat the leaves.
The solution: If possible, prune out and destroy webbing and damaged leaves. Rake and destroy leaf debris, and replace mulch under the tree each fall. Thoroughly spray the tree trunk with horticultural oil in early March to suffocate pupating larvae. You can also spray the tree with Bacillus thuringiensis kurstaki (Dipel, Thuricide, Javelin), or for serious infestations, spray with carbaryl (Sevin), diazinon, or malathion.
Another problem you may encounter with a mimosa is wilting. Leaves yellow and droop in early to midsummer. Tree branches will die over a period of several months.
Unfortunately, there is no control for the soilborne disease that enters through the tree roots. This disease that was discovered in the 1930s, has now spread throughout the South. The only solution is to remove the infected trees and make sure not to plant new mimosas in the same spot.
The chaste tree, also known as the Texas Lilac tree, produces beautiful blue-purple blooms that flower in the summer and is a good option for a cold-hardy tree that will last you a long time. In fact, I have a chaste tree that has been in my yard for over 20 years. It's a great option for smaller yards too, as it only grows 10- to 15-feet tall.
The crepe myrtle tree is known for its gorgeous flower clusters that bloom throughout the summer, its bright fall foliage in many cases, and its beautiful bark. This tree is very durable—it is drought-resistant and thrives in full sun, and can bloom in harsh conditions. The tree comes in pink, purple, red, and white variations.
Cherry Blossoms are sure to delight you with their beautiful blooms that come to life every spring, the 'Okame' variety blooming as early as Valentine's Day. There is a reason why many people crowd to Macon, Georgia each year—it's because of their enchanting rosy blossoms. These pretty in pink trees are also fairly easy to maintain and grow quickly when given full sun and well-drained soil.