A native of Asia, the mimosa tree (Albizia julibrissin) is a fast-growing member of the legume family that may be cultivated with ease in U.S. Department of Agriculture plant hardiness zones 6 to 9. A host of pros and cons are associated with the mimosa tree. Also called silk tree, the mimosa is somewhat controversial among gardeners because of its invasive tendencies, messiness and disease susceptibility, although many grow it for its ornamental beauty and low maintenance.
Pro: Ornamental Value
The mimosa tree is a strikingly beautiful tree, producing foot long, fern-like leaves that curl up in the evening and pink, fluffy, summer-blooming flowers that attract legions of bees and butterfies. Flowers are followed by long, flattened seed pods up to 8 inches long, which give the tree additional ornamental value. The leaves are open enough that sun can penetrate through the canopy, making it possible for grass to grow right up to the trunk.
Pro: Low Maintenance
Durable and adaptable, the mimosa tree will grow in average, well-draining soils, as well as poor, infertile ones. The tree will tolerate alkaline soils, salty coastal conditions and drought. Growth can be increased easily by watering regularly and planting the tree in a light, rich soil. Floridata comments that the tree will withstand "total neglect." Mimosa tree will produce its best flowers and growth in full sunlight, although it will also grow in partial sun.
Mimosa tree is highly susceptible to Fusarium wilt, a soil-borne fungus that prevents plant sap from moving through the tree properly. At the start of the disease, leaves wilt and yellow, sometimes dropping prematurely. Cracks then start to appear in the trunk, sometimes secreting gum or a frothy, odorous white liquid. The disease eventually causes the death of the tree, sometimes in as little as one month after the initial symptoms are spotted. No management strategies exist to control Fusarium wilt. The mimosa cultivars "Charlotte," "Tyrion" and "Union" may be resistant to the disease.
Con: Invasive Growth
Mimosa tree's fast-growing growth habit and tolerance of poor conditions makes it an invasive tree in some areas. The Florida Exotic Pest Plant Council lists mimosa tree as a Category I invasive exotic species, meaning that the tree poses a threat to local plant communities. The tree commonly naturalizes in disturbed areas and roadsides in the southeastern United States. Even where not invasive, the mimosa tree can be aggressive in the garden. The tree sheds seeds prolifically, and these seeds germinate easily to form new trees.
Frustrating for home owners, mimosas drop leaves, flowers and seeds pods that can accumulate and cause a litter problem on patios, walkways and driveways. If the falling seeds land in the garden, they will have to be weeded out or new trees will appear. In snowy or icy weather, the weak-wooded mimosa tree is prone to losing entire limbs. The branches aren't usually heavy enough to cause serious damage to a home, but it can cause the tree to look unattractive.