Mimosa bonsai (albiza julibrissin) care information
Mimosa, not native to North America, were imported first in 1745 from China and have become a popular shade tree in southern and coastal areas of the United States. Mimosas are easy to care for and make rather interesting bonsai due to their rather unique foliage and showy flowers. However, due to the size of their foliage they work best in larger bonsai forms such as kifu and dai.
The bonsai pictured here is by William N. Valavanis.
Notable Mimosa Characteristics
Their compound leaves are similar to those of ferns although they have more of a rounded edge to the tips. The pink, fragrant, showy, and silky-threaded flowers appear as puffs and cover the tree from April through July. The silky threads of the flowers lend the tree its silk tree nickname. One of the most interesting characteristics of mimosa is how their foliage folds closed at night through due to the absence of light (nyctinastic movement).
Care to keep your mimosa bonsai healthy
Mimosa do not like staying wet so make sure your mimosa bonsai is potted in well draining soil. As long as the soil is well draining it is tolerant of any kind of loamy, sandy, or clay based soil you choose. Also, the pH of the soil can tip either slightly alkaline or acidic without issues. They need to be kept in full sun so do not attempt to grow this bonsai indoors.
Mimosas do best in USDA zones 6-9, but can extend into zone 10. They will not do well in colder climates. Cold snaps will cause leaf yellowing. To prevent dieback protect the tree when temperatures may dip below 60 degrees F.
Wait for the soil to get close to dry before watering mimosa. They are drought tolerant so this should not be a problem. They are less tolerant of overwatering than underwatering. When you do water it may be easier to water the soil surface under the canopy when in bloom. This is because the flowers degrade when they get wet.
Training Mimosa into Bonsai Form
When training a tree into bonsai form it helps to use a style that resembles how the tree would otherwise grow in nature. The mimosa naturally develops a wide weeping canopy and is often found growing with multiple trunks. One may find it easier training mimosa into styles making use of these characteristics.
Mimosas have characteristics that make it difficult to train into bonsai yet it has other qualities that tend to offset the problems. The main issue people have with training mimosa is that, in general, their large compound leaves do not easily reduce in size. This makes it hard to maintain proper perspective in smaller bonsai forms. In addition, their branches can break easily and the bark is very soft. This makes wiring difficult. Wiring must be done on new growth using small gauge wire. The new growth will develop quickly so one may need to remove the wires between 12-16 days.
That being said, mimosa has many favorable qualities. First, the fast growth, as mentioned, means that the branches and trunk thicken quickly allowing the tree to develop taper faster than other species. Next, they can handle being harshly pruned back in the early spring. It takes root pruning equally well. Lastly, the fragrant and plentiful spring flowers make this a favorable selection for people looking to grow a flowering bonsai.
Common pests include scale, mites, and webworm. Check out our bonsai pests page for details.
Overall thoughts on Mimosa for bonsai
To conclude, it has been shown that the mimosa can be trained into an attractive flowering bonsai though not as easily as other species. As a result, it usually isn't most people's first pick. The tree is certainly not hard for a beginner to keep alive and enjoy. It is a hardy tree in the right temperature zones. However, it may be hard for a beginner to train a mimosa into proper bonsai form. As a result, I believe this tree is good for beginners wanting a flowering bonsai that are less concerned about styling. Those people wanting an easier tree to train into accepted styles may want to look into other species though others may enjoy the challenge.