There are ten times more different tropical plants than temperate climate plants and a large number have been grown as bonsai. There are significant differences in the ways that tropical trees grow and this dictates how they are trained as bonsai.
This introduction uses Surinam Cherry (Eugenia uniflora) as an example of how high standard tropical outdoor bonsai are trained. In Hawaii, this tree is one of the easiest and most popular due to its long life, attractive flowers and fruit, and easy care.
The tree is the Ham Kaneshiro memorial bonsai in the Hawaii State Bonsai Repository at the Fuku-Bonsai Cultural Center trained in the Chinese literati manner. I flowers in spring with fruits throughout the summer.
These trees are initially very slow growing and the seedlings in the center foreground are from last year's crop. The other three trees are from the previous year's crop. For most interesting bonsai results, start training the smallest one-year seedlings. As soon as they start germinating, pull them out, lay them on their side, bend them over rocks or wire them using the smallest bonsai wire. If you obtain larger trees grown in regular nurseries, you'll need to prune them down close to the ground to get any character. Otherwise you'll start with a tree in which the bottom section is straight and too stiff to change. Fuku-Bonsai grows outdoor tropical bonsai only for its exhibit collection. A small quantity will be grown but to only be available through our Hawaii State accounts, to members of the Mid-Pacific Bonsai Foundations and study groups.
PROPAGATION, EARLY TRAINING, & "ACCELERATED GROWTH"
Surinam Cherry is most often trained from seed. There are male and female plants with males being more stout and compact which is desirable. However it tends to flower with few if any fruit. Initially because I could see the differences, I selected only male plants and didn't get fruit! Now I don't select and grow males and female trees.
|FIRST YEAR TRAINING. Newly germinated seedlings on the right were partially pulled out, laid on its side, small rocks placed on them, the tips pinched, then allowed to grow. The one on the left had been wired to create some interest and a rock placed over the roots to protect them in the full sun.|
|SECOND YEAR TRAINING. The tree was grown in an aluminum foil column to develop a longer extended root system for a future "Root-Over-Rock" planting. Surinam Cherry becomes stunted and will not develop when grown in a rock cavity. So root-over-rock methods are recommended as it will allow repotting from time to time to create more vigorous growth to allow bonsai training.||
|This photo shows the root system being developed with the aluminum foil column. The trunk has also been wired and growth tips pruned to start creating branches.||
|The two year old seedling has been pruned back, reconed in foil again as show in the center. The one year seedlings have been unwired, pruned, and will be allowed to grow strongly for another year or two, then placed into "accelerated growth" for a few years.|
|These two trees are six year old seedlings in cut down 5" square pots that were intentionally wire-marked to try to create interesting character. They are the same age as the tree below that was also pre-trained, then placed into accelerated growth in a half-flat that held more than four times as much potting media and allowed to grow vigorously.|
|ACCELERATED GROWTH! Three years ago, a three year old partially pre-trained seedling was planted in a 10"x10"x2" deep "half-flat" with a coarse bottom, some body media, then a "plastic separator" that prevented roots from growing down. So roots grew out and only went down after they passed the plastic separator. The top half of a 5" nursery pot serves as a collar and the tree is planted high and the roots are running throughout the half-flat to produce vigorous growth and thicken the trunk. A weed mat (with the 5"x5" center cut out) covers the exposed media to hold back weeds and to serve as a mulch so it requires little care during the 3+ years in accelerate growth.|
|With the plastic collar and weed mat removed, expose the base of the trunk. Surinam Cherry tends to throw out stolens from the root base and a few have been retained. Excess growth in the wrong places have been removed. The large branches were small branches when accelerated growth began.|
|Growth was cut back to the primary trunk and branches that have greatly thickened. While there is some trunk interest because of the pre-training, there is little trunk taper because all thickening was done together. If the main apex is removed, a new apex selected, and the tree placed back into accelerated growth, there would be improved trunk taper.|
|The plant was pulled out of the flat and the root system cut away just above the plastic separator. That leaves all the roots that had developed below the plastic separator intact and still in the form of the half-flat. The plastic separator remains in place and the photo shows that the roots were forced to grow outwards, then down so the most efficient roots closest to the trunk-root base were recovered quickly and it will be easy to repot.|
|The six-year old tree easily was potted into a shallow 9" diameter saucer less than 1" deep that is used in our 1:!0 Project. A rock was placed to "visually support" the trunk.|
|Another view of the repotted six year old tree. This tree will be given to Ryan Chang to continue the training in Honolulu. Ryan has planted some seeds of Surinam Cherry and we will be selecting and working on other trees suitable for Hawaiian hobbyists to grow outdoors all year around.|
MATURING & APPROPRIATE STYLING CONCEPTS
Surinam Cherry grows to about 15' tall with multiple trunks and arching branches. The trunks are fairly slender so thick heavy trunks are primarily created by greatly reducing a larger tree that is usually grown in the ground. Branches sprout from old wood. The tree is relatively easy to train as it's arch type branches become more refined with age.
Surinam Cherry naturally produce multiple trunks as it sends out new ratoon growth from the root base. However, it is easier to plant several seeds in a fairly tight grouping and shear it repeatedly to create a lot of branching. Then it a challenge to create a clump-type multiple tree grouping and I was quite successful. When trees were too close together, I stuck a screwdriver between them, pried them apart, and stuck some small rocks between the trunks to create different spacings.
Creating a heavy trunk is difficult and this tree was planted in the ground for several years, then severely reduced resulting in the large scar on the trunk. I happen to have a black cloth as a background during the flowering season for this photo.
On Kauai, they have a Dwarf Surinam Cherry with much smaller more compact leaves. A percentage of those grown from seed have the dwarf characteristics while others come out leggy with long branch internodes. The two photos below are of that dwarf variety.
|This is my older tree that is about 30 years old from seed. This year there was a profusion of flowers and fruit. But unlike the common variety, the fruit does not ripen together with a few turning yellow, then orange and red before dropping off.|
|This was a tree with a weird double bend in the trunk and I happened to find rock that fits perfectly in those bends so the trunk appears to go up the rock, around the back, then coming forward, up and out as if it is hugging that rock. This is a small tree in an 8" round pot and about 8" tall with a 1/2" thick trunk.|
The tropical Eugenia family also includes Jaboticaba aka Brazilian Grape and the Australian Bush Cherry. Although each has pros and cons, they are amongst the better tropical outdoor bonsai. They require a lot more light that ficus. I do believe they would require much more light than possible with common fluorescent lighting so recommend them only for year around tropical outdoors. But I must admit that I've heard that they have been successfully grown. We are building a trial group of those with metal halide light units and a range of high-light plant experience. If you meet these criteria, are willing and able to produce reports, please consider joining the Mid-Pacific Bonsai Foundation and the study group that will be testing new plants for indoors under high light conditions and outdoors when night temperatures are above 55 degrees F. Please contact me at email@example.com if interested. ~~~David