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Brazilian Rain Tree Bonsai Have Many Charms

December 08, 2023Beginners, Care, General, Plants

A tall Brazilian rain tree bonsai in front of a grey wall.

The Brazilian rain tree is a delightful addition to any bonsai collection. In this article, we’ll explore the characteristics that make this species attractive as bonsai and provide tips on care.

As bonsai hobbyists gain experience and confidence successfully caring for their first trees, they invariably start to acquire specimens of different species. The lovely Brazilian rain tree is a prime example of a tree suited to beginners with a bit of bonsai success under their belts. 

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About the Brazilian Rain Tree

The aptly named Brazilian rain tree hails from the coastal forests of Brazil. This species is a member of the legume family, and its official name is Chloroleucon tortum (formerly Pithecellobium tortum). 

The Brazilian rain tree is a delightful bonsai subject. It boasts delicate compound leaves consisting of three pairs of leaflet stalks, each with 5 or 6 tiny leaflets on each side. The leaflets have the unique and charming property of folding up in the evening and unfurling with the sunrise. The leaflets also fold or partially fold to adjust to intense light as well as rainy or dry conditions.

The compound leaves of the Brazilian rain tree feature stalks with tiny leaflets.

The Brazilian rain tree has smooth gray bark which peels in spots on mature specimens. Young, cylindrically shaped trees sport a top canopy of leaves. As they mature, the growth takes on a twisted pattern with sharp angles.

A downside of the rain tree is its tendency to grow spiky thorns. The thorns emerge at branch nodes, usually in pairs. Although they add highly desirable visual interest to the tree, the sharp thorns definitely make pruning and wiring more challenging.

Brazilian rain tree leaflets fold at night. Note the tree’s sharp thorns.

When it flowers, the rain tree has puffy white flowers with a pleasant fragrance and a corkscrew-shaped fruit. Be aware that many Brazilian rain trees kept as bonsai never produce flowers.

Brazilian rain tree is related to several other legume-type trees cultivated as bonsai. These include the Texas ebony (Pithecellobium flexicaule) and several mimosa-type species such as the Silk tree (Albizia julibrissin). These trees all have compound leaves with leaflets that fold at night, as well as thorny branches and puffy flowers.

Bonsai Care for the Rain Tree

Brazilian rain trees thrive outdoors during the warm, sunny summer months, when conditions in most temperate areas are similar to its native climate. As a tropical species, it can tolerate temperatures down into the mid-40’s, but it cannot survive cold weather. 

The rain tree should come indoors when nighttime temperatures start to fall around 50 degrees. While indoors, it needs a position near a sunny window and will benefit from the addition of a grow light.

Watering

When it comes to watering, the rain tree prefers that its soil stay evenly moist. In addition to frequent watering during the dry winter months, keeping the bonsai on a pebble-filled humidity tray and misting it regularly can help it stay healthy. 

This species is able to tolerate being dry for only a short time. One sign that the tree’s soil needs a moisture check is when the leaflets fold during daylight hours. 

Left dry for too long, the Brazilian rain tree will respond to the stress by dropping its leaves. If this happens, don’t automatically assume the tree has died. Keep the tree in place and water it regularly. In several weeks, it may recover and start sprouting new leaves. 

Pests & Diseases

One advantage of a Brazilian rain tree is its resistance to diseases and pests. Sometimes spider mites and aphids try to take up housekeeping in a Brazilian rain tree, particularly those kept indoors. A spray of neem oil or a simple spray made with dish soap can usually keep those unwelcome guests at bay.

Root nematodes can also pose issues, especially for trees that reside outside in contact with the ground. It’s always a good idea to keep bonsai off the ground during the growing season.

Styling

The Brazilian rain tree’s natural growth habit lends itself well to styling as a formal upright or informal upright bonsai. Indeed, these styles are the most popular for this species. We also see other styles, such as cascades or twin trunks and clumps, occasionally used .

Pruning & Repotting

It’s important for owners of Brazilian rain tree bonsai to know that these trees are susceptible to dieback when pruning. This means that if a branch is trimmed closely, the desirable adjoining area of that branch will likely die back to the next node. For this reason, don’t use concave cutters with Brazilian rain trees and always leave a stub of the branch being trimmed. The stub can be removed once it completely withers and dies. 

Repot rain trees every two years in the spring or early summer. After repotting, keep the tree in a shaded location for a week or so to recover from the stress before gradually moving it back into the sun.

Wiring Brazilian rain trees is possible, however the thorns and the delicate leaflets make the task difficult. Some hobbyists defoliate trees and remove thorns prior to major wiring work. However, most enthusiasts prefer to shape these trees using guy wires instead of wiring the tree branches. 

Brazilian rain trees also respond well to techniques such as air layering. I’m planning to try this in the spring with my own Brazilian rain tree, pictured in the feature photo. I’ve identified a branch about a third of the distance from the top that will make an excellent leader, introduce needed trunk taper, and result in a tree with better balance. If my air layer is successful, I will have not one, but two nice Brazilian rain tree bonsai! 

Acquiring a Rain Tree

The Brazilian rain tree is a tropical tree not commonly found in the U.S. except for its use as bonsai. Don’t expect to find it at a typical nursery or garden center. Retailers specializing in bonsai are the best sources for enthusiasts who want to acquire either a pre bonsai or a more mature rain tree specimen.

Keep in mind that these trees are rather pricey. If you are still a relative beginner to the hobby, look to find a decently priced nicely sized pre bonsai. Rain trees are rapid growers, so with a few short years of training, you can develop a respectable Brazilian rain tree bonsai. 

If you are interested in other tropical bonsai, check out our articles about ficus and schefflera and dwarf jade

The Brazilian rain tree is a popular bonsai species, suitable for beginners beginning to branch out from their early success with other species. Its tiny leaves, interesting bark and twisting growth habit make it an excellent bonsai subject.

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